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In underground coal gasification (UCG), the backfilling body is utilized to reinforce the isolated coal pillars and provide support for the combustion cavity, but elevated temperatures can lead to a degradation in the carrying capacity. This paper presents an innovative high temperature resistance backfilling material for UCG. The evolution law and high temperature resistance mechanisms of its bearing capacity under high temperatures were mainly investigated, including its thermal expansion, compressive strength, acoustic emission characteristics, thermal stability, phase composition, micromorphology, and pore structure. The result indicates that the calcium aluminate cement (CAC) - fly ash (FA) backfilling body exhibited a non-linear variation in compressive strength with increasing temperature. The compressive strength still maintains 5 MPa at 1000 ℃, meeting the requirements for coal mine backfill. The FA induces secondary hydration in the backfilling body at elevated temperatures, resulting in the formation of a more compact C-A-S-H gel phase. Furthermore, the formation of AlO(OH), C 12 A 7 , and C 6 S 6 H is another reason for the enhancement of the high-temperature resistance of specimens. After 600 ℃ treatment, the porosity of specimens exhibited a significant increase, reaching 30.57 % at 1000 ℃. The thermos-mechanically coupled constitutive equation of the backfilling body was constructed, showing that as temperature rises, the brittleness diminishes and the damage factor experiences a substantial increase after 500 ℃. Experimental results provided strong technical support for strata control of UCG. • A high temperature resistance backfilling material for UCG was proposed for the first time. • The relationship between mechanical properties and thermal physical properties of CAC-FA backfilling body was studied. • The high temperature resistance mechanism of backfilling body was described. • The constitutive model of CAC-FA backfilling body for UCG was established. [ABSTRACT FROM AUTHOR]

Geopolymer materials offer environmental benefits and strong mechanical properties but face limitations such as efflorescence, shrinkage, thermal stability and poor mechanical performance at high temperatures. This study introduces a novel solution using silane-functionalized graphene oxide nanocomposites (GO-APTS) to address these challenges. Experiments on metakaolin-based geopolymers demonstrate that incorporating GO-APTS improves dispersion, enhances mechanical strength, refines pore structures, and boosts resilience to high temperatures while reducing shrinkage and efflorescence, without compromising the workability of the mixes. Although the structural integrity of the material at nanoscale degrades beyond certain temperatures, the overall thermal resistance is significantly increased, with treated geopolymers displaying a ∼6 % improvement in porosity, ∼20 % higher residual compressive strength and ∼15 % reduction in shrinkage compared to control samples after exposure to heat. Our work reveals the promising potential of silanized graphene oxide nanocomposites in crafting cementitious materials suitable for high-temperature applications, paving the way for their broader use in innovative construction and industry solutions. • GO-APTS significantly enhance mechanical strength and thermal properties of geopolymer. • GO-APTS reduces shrinkage and efflorescence in geopolymer. • APTS delays deterioration of GO up to approximately 620 °C – compared to 580 °C for pure GO. • Formation of new geopolymer reaction products at elevated temperatures are observed. • Simultaneously, structural deterioration and nanoscale degradation are evident. [ABSTRACT FROM AUTHOR]

Titanium dioxide hollow microspheres (HMS-TiO 2) were successfully synthesized through a sol-gel and subsequent high-temperature calcination method using a hard template. These microspheres exhibit an average particle size of about 13.66 μm and a shell layer thickness approximately 1.18 μm. Furthermore, the thermal insulation effect is evident in cementitious materials coated with an HMS-TiO 2 -based composite film. The maximum average near infrared (NIR) reflectance and thermal insulation temperature difference of these coated materials are 46.81 % and 9.3 ℃, respectively. Notably, the modified composite film displays excellent mechanical and impermeable properties when applied to the surface of cement mortar samples. These comprehensive results indicate that introducing HMS-TiO 2 with the synergy of structure and composition significantly enhances the thermal, mechanical, and durability properties of modified waterborne coatings on cement-based materials. This augmentation makes them well-suited for thermal insulation and heat preservation applications in building structures. • Micro-scale hollow TiO 2 was synthesized using a hard template method. • The synergy of structure and composition is crucial for cement coatings. • Hollow TiO 2 -based coatings show excellent thermal insulation properties on buildings. [ABSTRACT FROM AUTHOR]

This paper investigates the synergic effect of both hydrated lime and guar gum stabilisation on the mechanical, thermal and hygroscopic properties of a compressed earth material for building applications. The stiffness, strength and compression energy at failure of both unstabilised and stabilised earth samples were measured at different curing times by means of compression tests. The moisture-dependent thermal conductivity was instead determined via the hot disk technique at a constant temperature of 25 °C and at the three different relative humidity levels of 0 %, 50 % and 95 %. The specific heat capacity was measured by means of calorimetry tests at the three temperature levels of 32–34 °C, 34–36 °C and 36–38 °C. The moisture adsorption-desorption curves were measured by performing a cyclic variation of relative humidity between 0 % and 95 % at a constant temperature of 25 °C via the dynamic vapour sorption (DVS) technique. Results from the experimental campaign show that the proposed stabilisation methods increase both the peak compressive strength and compression energy at failure while the addition of the biopolymer guar gum induces a progressive reduction of stiffness. The thermal properties of the earth are only marginally affected by the addition of hydrated lime and guar gum, with stabilised samples exhibiting similar levels of thermal conductivity and specific heat capacity to those of the unstabilised ones. Finally, the biopolymer stabilised samples exhibited a similar hygroscopic behaviour to that of unstabilised ones, whereas the addition of hydrated lime deteriorates the moisture adsorption capacity of the material. • Earth samples are stabilised with hydrated lime and the biopolymer guar gam. • Biopolymer stabilisation increases strength and compression energy while reducing stiffness. • Lime stabilisation increases stiffness and strength but reduces ductility. • Lime and guar gum stabilisations marginally affect the thermal properties of the earth. • Moisture adsorption is preserved by guar gum stabilisation and reduced by lime stabilisation. [ABSTRACT FROM AUTHOR]

The utilization of in-situ lunar resources through the additive manufacturing of lunar regolith (LR) has attracted considerable interest. Sintering of LR is considered a promising method for lunar construction due to its high utilization rate and excellent service stability. However, numerous studies have been carried out on Apollo series LRs with similar chemical compositions in air or inert gas atmospheres. The effects of the lunar ultra-high vacuum conditions and the complex chemical composition of LRs on the sintering process require extensive investigation. In this study, a self-developed Chang'E-5 lunar regolith simulant (LRS) with a high-Fe content was used as the only raw material to investigate its potential applicability for future lunar construction in vacuum environment. The effects of sintering temperature on the microstructure, linear shrinkage, bulk density, weight loss ratio, and mechanical and thermal expansion properties were investigated. The results show that the linear shrinkage and weight loss ratio increase with increasing sintering temperature. However, the bulk density and unconfined compressive strength (USC) initially increase and then decrease, with the sample sintered at 1075℃ giving the highest bulk density of 2.10 ± 0.03 g/cm3 and a USC of 31.19 ± 1.96 MPa. This is attributed to the transformation of the sample sintered at 1090℃ into a semi-porous material with many cracks. Furthermore, the mechanism of pore and crack formation was revealed. The coefficient of thermal expansion (CET) of the sintered samples is approximately 7×10–6°C−1, which maintains a good service stability after cyclic temperature stress from room temperature up to 200°C. Both the USC and CET of the sample sintered at 1075℃ are superior to those of common terrestrial concrete materials. This indicates that the vacuum sintering process appears feasible for the production of building materials with sufficient mechanical strength and thermal durability for lunar base construction. • A Chang'E-5 lunar regolith simulant was first developed that differed from the widely studied Apollo series lunar regolith. • The effects of sintering temperature on microstructure, phase change, linear shrinkage, bulk density, mechanical and thermal expansion properties were investigated in vacuum environment. • The mechanism of pore and crack formation was revealed. • The obtained sintering materials exhibit superior compressive strength and service stability to those of common terrestrial concrete materials. [ABSTRACT FROM AUTHOR]

The black appearance of asphalt pavement easily absorbs a large amount of solar radiation in hot summer to lower its anti-deformation ability, and asphalt pavement cools down quickly in cold winter to cause cracks. To solve these problems, thermochromic core material (TCM) was encapsulated by the shell material of urea-formaldehyde (UF) resin to prepare thermochromic microcapsule (TM) using situ-polymerization. Then the surface morphology, particle size distribution, chemical composition, phase change property and thermal stability of TM were characterized. After that, emulsified asphalt and acrylic emulsion were selected as film-forming substances to prepare thermochromic asphalt-based composite coating (TACC) after adding different dosages of TM. The surface morphology, chemical composition, thermal storage capacity, phase change property and spectral reflectance of TACC were studied. The results show that TCM is successfully encapsulated by shell material which restricts the thermal conductivity of TCM, making heat transfer process of TM become gentler. Also, the phase change property of TM is still better due to excellent phase change property of TCM. Further, TM particles with the size range of 3.2–4.8 μm are uniformly distributed on TACC surface and show better dispersion in emulsified asphalt. Additionally, TM enhances the thermal storage capacity and thermal stability of TACC. The heat exchange efficiency between asphalt pavement and surrounding environments is increased by added TM particles, improving the thermal stability of TACC. Finally, the increased spectral reflectance in the near-infrared region reflects more solar radiation in hot season because of high reflectivity of TACC on asphalt pavement, which lowers asphalt pavement temperature to improve its anti-deformation ability. [Display omitted] • TACC is developed after adding prepared TM in emulsified asphalt and acrylic emulsion. • The shell material limits thermal conductivity of TCM to enhance thermal stability of TM. • Prepared TM obviously improves thermal storage capacity and thermal stability of TACC. • Heat exchange efficiency between asphalt pavement and environments is increased by TM. • Developed TACC reflects more solar radiations to regulate asphalt pavement temperature. [ABSTRACT FROM AUTHOR]

The extensive mining of natural resources, such as sand, for the construction industry, poses a hazard to the environment. To preserve the environment, the researcher must thus take into account the use of industrial byproducts rather than natural materials. The use of sawdust (SD) produced by the wood industry in foam concretes (FC) has been investigated in this study. This study examined the physical, mechanical, thermal, microstructural and durability characteristics of FC containing SD as a replacement of silica sand (SS) in the rates of 0, 25, 50 and 100 %. Two different SD sizes of 0–4 mm (SD4) and 0–1 mm (SD1) were used in the fabrication of FC mixtures. Protein-based foam agent was used to create FC mixtures. Fourteen mixtures with a 0.6 water/binder (w/b) ratio were produced at two different cement contents of 400 kg/m3 and 500 kg/m3. The fresh, mechanical, physical, and sorptivity characteristics of the FC mixtures were investigated in relation to the impacts of cement dosage, SD size, and SD replacement levels of SS. Durability of FC against high temperature, sulfate attack and freeze-thaw cycles was assessed. Costs and CO 2 emissions from the blends were also assessed. The outcomes revealed that a 25 %SD1 integrated FC mixture with a cement content of 500 kg/m3 generated the highest 28-day compressive strength of 3.56 MPa with a 20 % strength loss as per the Ref.500 mixture. 17 % lower thermal conductivity was gained with the inclusion of 100 %SD4 as per the Ref.400 mixture. The mixture with 50 %SD4 and 400 kg/m3 cement dosage exhibited the best resistance to high temperature. The mixture with 25 %SD1 and 400 kg/m3 cement dosage showed the best frost resistance. SD incorporated mixtures showed better durability performance than the reference mixtures. • This study evaluated the sustainable use of different sizes of SD aggregates in eco-friendly FC. • Fresh, thermal, mechanical and microstructural properties of FC were studied. • Transport properties, cost investigation and environmental impact of FC mixtures were also investigated. • Durability performance for sorptivity, sulfate attack, high temperatures, and freeze-thaw cycles was also carried out. [ABSTRACT FROM AUTHOR]

Interest in utilizing industrial waste and by-products in construction materials is growing, given recent concerns about sustainable practices aligning with the principles of the circular economy. Within this context, compressed earth blocks (CEBs) are emerging as an alternative to traditional building materials, offering cost-effectiveness, energy efficiency, and reduced environmental impact. This systematic review comprehensively explores the incorporation of industrial waste and by-products, including construction and demolition waste (CDW), in the production of CEBs. An approach based on the PRISMA model is adopted to analyze the outcomes from primary scientific databases, namely Scopus and Web of Science. The advantages and limitations of incorporating industrial waste and by-products into CEBs are thoroughly discussed. The results show that these waste materials can improve the mechanical, durability, and thermal insulation properties of CEBs. However, careful selection and processing are necessary for compatibility with CEB production. Factors like particle size distribution, chemical composition, and processing techniques significantly influence block performance. This research highlights the potential for more sustainable practices in CEB production while enhancing the mechanical and functional properties of this building product. The findings contribute to advancing knowledge in the field, benefiting researchers, practitioners, and policymakers interested in sustainable construction practices. • Incorporating industrial waste/by-products into compressed earth block is reviewed. • Mechanical, thermal and durability properties of waste-based CEBs are analyzed. • Industrial waste and by-products can improve the functional performance of CEBs. • Research gaps include compatibility issues and manufacturing standardization. • In-depth studies on environmental impact assessment are encouraged. [ABSTRACT FROM AUTHOR]

Studying the effects of elevated temperatures on nanoconcrete is a complex issue due to multiple factors and conditions that affect it. A comprehensive study is necessary to determine the real behavior of nanomodified concrete at high temperatures using different nano-modifiers for various nanomaterials, including those derived from waste. This study investigated the effect of elevated temperatures (200 °C, 400 °C, 600 °C and 800 °C) on concrete containing nano-silica, nano-aluminum, and nano-glass materials as a partial replacement for cement at percentages of 1, 2, and 3 % by weight. Compressive strength test and XRD, TGA and SEM were performed to determine residual Compressive strength, chemical composition, mass loss, and microstructure, respectively. The results showed that incorporating nanomaterials into concrete boosted its residual compressive strength at elevated temperatures. Optimal percentages of nano glass and nano-silica were 1 % at room temperature and 200 °C, and 3 % at 400 °C and 600 °C, respectively. For 800 °C, 2 % nano aluminum was most effective. The findings conform with dense microstructure, particularly in ITZ because of the filling effects and higher CSH with a reduction in calcium hydroxide that was observed by XRD, as well as the correlation with lower mass loss of nano concrete. • Nano modified concrete showed optimal performance before and after exposure to elevated temperatures. • Using 3 % nano-silica, 2 % nano-aluminum, and 1 % nano-glass at elevated temperatures greatly improves the behavior of concrete. • Improvement in microstructure and weight loss were observed through TGA and SEM and analyzed by XRD when using nanomaterials. • using of nano-sized recycled glass in concrete showed good results at different temperatures. [ABSTRACT FROM AUTHOR]

Integration of phase change materials (PCMs) into buildings contributes to mitigating indoor temperature fluctuations, offering opportunities for alleviating energy crisis. However, prevalent PCM integration methods commonly suffer from shortcomings in mechanical properties, compatibility, and environmental sustainability, restricting their applications. This study developed a novel shape-stabilized PCM (SSPCM) using cenospheres from coal-fired power waste and bio-based PCMs from vegetable oil by-products, subsequently sealed with silica coatings to inhibit PCM leakage and improve thermal stability, termed as SCS@PCM, exhibiting melting enthalpy up to 103.9 J/g. SCS@PCM was then integrated into cement mortars by replacing fine sand to fabricate thermal storage cement-based materials (TSCM), followed by assessments of their microstructural, mechanical, and thermal properties. The results showed that the silica coating helps to lowrer adverse impact of SCS@PCM on the compressive strength and thermal conductivity of TSCM. TSCM containing 30.0 vol% SCS@PCM reached a 28-day compressive strength of 45.3 MPa, exhibiting only a 17.4 % reduction compared to the control group, notably less than reductions observed for other SSPCMs reported in literature. Moreover, integration of SCS@PCM improved thermal storage capacities and decreased thermal fluctuation rates of TSCM, evidenced by a 4.7 ℃ decrease in peak temperature at dosage of 30.0 vol%. This study endeavors to develop an eco-friendly TSCM with excellent thermal and mechanical properties, providing insights for applications in improving the thermal regulation and energy efficiency in building roofs. • An eco-friendly, compatible, and robust shape-stabilized PCM was developed using cenospheres and bio-based PCMs. • Effective inhibition of PCM leakage and improved thermal stability of SCS@PCM was achieved by the SiO 2 coating. • SCS@PCM replaced up to 30 % by volume of fine sand without noticeable reduction in the mechanical strength of cement mortar. • SCS@PCM significantly improved the heat storage and temperature regulation capabilities of cement mortar. [ABSTRACT FROM AUTHOR]

There has been a noticeable global trend in the usage of natural, ecologically conscious fibers as reinforcements in the production of inexpensive, lighter polymer composites. Specifically, the basalt natural fibers are the most intriguing due to their characteristics among the various types of natural fibers (i.e., plants, animals, or minerals) that could be utilized as reinforcement. In the composites sector, basalt fibers (BF) have garnered a lot of interest due to their exceptional mechanical and thermal capabilities, as well as their chemical stability. In comparison to carbon, glass, or other mineral fibers generally, the environmental effect of the entire complex of technical processes involved in generating and using basalt fibers is significantly lower. Within this framework, this suggested review seeks to investigate and analyze the behavior of basalt mineral materials in the forms of fiber, powder, and mats when it is reinforced with different polymer matrices. Additionally, this study discusses the basic methods of producing basalt fibers, their characteristics, composition, and the impact of surface treatment on the fibers. Further sections address the developments in 3D printing and its possible applications in a variety of industries, encompassing mechanical, thermal, tribology, and water absorption/wettability studies. It has been noted that for both structural and non-structural applications, basalt fibers are the most advantageous substitutes and prospective reinforcements in place of glass fibers. While the quantity of BF has a significant impact on mechanical durability and basalt-fiber reinforced composites' (BFRCs) performance over time, another important factor that affects how well BFRCs perform is fiber-matrix interaction. To enhance this fiber-matrix interaction, a variety of chemical treatments (acidic, basic, and plasma) on the basalt fiber are being reported by several studies. The primary drawback of this chemical treatment is that the basalt fiber is harmed by high acid or alkali concentrations. During the long-term chemical treatment, the corrosive layer thickness significantly increased, mostly due to the presence of SiO 2. The extant research clearly indicates that augmenting the volume fraction of basalt fibers improved the composite's capacity to endure impact and absorb energy. In many experiments, basalt fibers have demonstrated greater resistance to moisture conditions when compared to natural fibers derived from plants. Since the basalt is an extremely durable and rigid material, it may be used to make frictional materials to minimize wear and friction. However, increased mass manufacturing of basalt fibers will be necessary to fulfill demand before they can be widely used as reinforcing element for structural composites. This might also make basalt fibers more affordable than more conventional reinforcements like glass and carbon fibers. [Display omitted] • Basalt fibers as a sustainable and ecologically benign reinforcing element. • Basalt fibers might be used in place of naturally obtaining crops or plant fibers. • Basalt fibers improved the composite's shock resistance and energy absorption. • Electro-technical applications can benefit from basalt fibers. • Basalt fibers are useful for the transportation and storage of radioactive objects. [ABSTRACT FROM AUTHOR]

In this study, we successfully applied an external magnetic field for the first time in preparing oriented steel fiber reinforced mullite castable (OSFRMC). The impact of the castable's rheology, duration of exposure to the magnetic field and strength of the magnetic field on the orientation of steel fibers and the properties of the refractory castable was investigated. When the duration of exposure to the magnetic field was set at 60 seconds and the strength of the magnetic field was 2.5 mT, an orientation index of steel fibers in the refractory castable of 0.96 was achieved. This specific castable contained 6 wt% of microsilica. Moreover, the castable with a high orientation index (0.96) of steel fibers exhibited significant improvement in mechanical strength and thermal shock resistance compared to the untreated castable. In order to investigate the fracture behavior of steel fiber-reinforced refractory castables with different fiber orientations, a comparative study was conducted using force-displacement curves and digital image correlation techniques. The primary factor behind this improvement is the directional alignment of steel fibers, which enhances the bridging effect and crack deflection toughness within the material. • Optimization of castables' rheology was a key step to prepare the castables. • The orientation of steel fiber had a great influence on the properties of castables. • Magnetic field was applied to prepare the castable with oriented steel fibers. [ABSTRACT FROM AUTHOR]

The use of bio-based building materials is a sustainable opportunity to reduce the environmental footprint associated with the construction sector. The achievement of this objective is primely achieved through the valorisation of vegetable waste, resulting in a reduction in the use of primary source material and waste generation. Within the scope of this study, the focus is directed towards research concerning the thermal, acoustic, and fire behaviour properties of bio-based building materials. This study conducts a comprehensive bibliometric analysis encompassing all documents meeting these criteria within the Scopus database, spanning two decades, from 2003 to 2023. The comprehensive analysis covered a total of 1081 documents, which were analysed. This analysis furnishes insight into various facets, including the temporal evolution of publications, journals boasting the highest publication counts and impact, influential research areas, countries with substantial contributions and their collaborative patterns, noteworthy affiliations, prolific authors, and seminal documents, alongside recurrent keywords. The objective of this comprehensive study is to provide a detailed analysis of the documents published up to the present day, in order to identify research gaps and potential opportunities in this field, to assist new researchers interested in the subject. The analysis reveals that bio-based building materials have gained substantial attention over the past decade. With each passing year, the published documents have increased their impact and become more specific, underscoring the growing importance of this subject. This evolution has also fostered a broader network of researchers engaged in this field. However, it is noteworthy that the characterization of these materials focuses predominantly on their thermal properties, while research avenues related to acoustic and fire properties remain less explored and present opportunities for future investigation. • This study contributes to identify research gaps and potential opportunities in the field of bio-based building materials. • Studies in bio-based building materials have shown an annual growth of the 25% since 2014, being a topic on the rise. • France and China are the countries with the highest scientific publication on bio-based building materials. • Keywords play a crucial role in making visible the research within bio-based building materials. • "Thermal Conductivity" and "Thermal insulation" are the most repeated keywords in this field. [ABSTRACT FROM AUTHOR]

This study explores the use of recycled aggregates (RA) from concrete, replacing 100% of Cruched Sand (CS) by volume. It focuses on their processing methods and their performance compared to Self-Compacting Sand Concrete (SCSC) and Vibrated Concrete (VC). Fresh properties, including workability, are affected by RA, but RA-based SCSC meets standards. While RA-based SCSC initially had lower strength than CS-based SCSC, it improved after 28 days, yielding similar mechanical properties. RA use led to lower density compared to CS in concrete. Thermal conductivity was insulating, slightly lower in RA-based SCSC. Porosity decreased with age in all mixtures, with RA-based concrete having initial higher porosity and capillary absorption. Microstructure showed finer crystal growth in RA-based concrete. RA in SCSC exhibit a superior Interfacial Transition Zone (ITZ) compared to CS concrete, enhancing homogeneity and durability. This research supports sustainable RA use in concrete, that contingent on precise mix design and method processing of waste concretes, as well-designed SCSC. RA in construction provide scalable and economic benefits, including cost savings, infrastructure investment, sustainability, and market expansion. This contributes to the provision of environmentally friendly building materials and the sustainability of the industry. [Display omitted] • RA affects SCSC workability. • RA enhances thermal conductivity. • SCSC RA demonstrates durability. [ABSTRACT FROM AUTHOR]

Massive concrete structures are susceptible to thermal cracking due to the large surface-to-internal temperature gradients induced by the exothermic cement hydration, threatening their durability and safety. This study explored a novel thermal-tailored strategy to mitigate thermal cracking of cement-based materials by incorporating carbon fibers (CF) and liquid-metal-based microencapsulated phase change materials (MEPCM). Specifically, spherical MEPCM composed of In-Bi-Sn alloy cores coated by polyvinyl alcohol shells was prepared through a high-speed liquid-phase dispersion method, with average diameters of 36.26 μm and a high volumetric latent heat of 214 MJ/m3. The synergistic effect of CF and MEPCM on the microstructure, mechanical and thermal properties of cement mortars was further investigated. Upon adding 0.3 wt% of CF and 3.2 vol.% of MEPCM, the flexural strength of cement mortars exhibited a significant increase of 30.3 %. Microanalysis revealed that the molten MEPCM could flow to fill the pores and microcracks within its surrounding matrix and form a network skeleton with well-dispersed CF, imparting flexibility to the typically rigid cement hydrates. By this way, the thermal conductivity of cement mortars was increased by 21.7 % and internal temperature rise was decreased by 12 ℃ by adding 4.8 vol.% of MEPCM, contributing to the mitigation of risks associated with thermal cracking. The research outcomes will provide valuable insights into the development of thermal cracking-resistant cement-based materials in a highly efficient way. • Fabrication of microencapsulated phase change materials (MEPCM) based on In-Bi-Sn alloy was achieved. • The synergistic effects of carbon fiber (CF) and MEPCM on the performance of cement mortars was evaluated. • Incorporation of CF and MEPCM significantly enhanced the flexural strength and thermal conductivity of cement mortars. • Cement mortars containing 0.3 wt% CF and 4.8 vol.% of MEPCM exhibited a maximum internal temperature reduction of 12 ℃. [ABSTRACT FROM AUTHOR]

Using natural porous and fibrous materials for acoustic and thermal conditioning in the construction sector is a solution to achieve a comfort level in buildings. The novelty of this research work lies in employing agricultural and agro-industry waste to solve noise and thermal insulation problems. This study was conducted to investigate a multilayered panel made of fruit stones and coconut fibre from agro-industry waste. Acoustic absorption, and acoustic and thermal transmission, tests were run on four different fruit stone types, olive, cherry, apricot and peach, plus a coconut fibre layer. Although they are not structural elements, bending tests were run to ensure panels' structural integrity. Acoustic tests complied with the recommendations of Standards ISO 10534–2 and ASTM E 2611–09, based on the standing wave tube to obtain the acoustic absorption coefficient and sound transmission loss, respectively. Standard EN 12667 was considered for the thermal test to determine the thermal conductivity coefficient based on the hot plate method. The results show an average sound absorption coefficient above 0.5 and sound insulation over 25 dB within certain frequency ranges. The cherry panels had absorption values of around 0.7 and apricots had sound insulation values of up to 30 dB. Samples' thermal transmittance coefficient values were between 3.0 and 3.4 (W/m2K), which indicate panels' ability to provide thermal insulation. The cherry and olive panels obtained the lowest thermal conductivity (around 0.14 W/mK). The backing effect of the coconut fibre layer improves all the panels' acoustic absorption and thermal properties. [Display omitted] • These natural materials reduce the environmental impact and support a more sustainable construction industry. • Acoustic and thermal properties of multilayer panels composed of fruit stones and coconut fibres. • The panels made of the studied materials, have inherent strength and stiffness that allows them to be structurally stable. • The results show an average sound absorption above 0.5 and sound insulation above 25 dB in certain frequency ranges. [ABSTRACT FROM AUTHOR]

This research investigated the development of a fast-drying silica-based binder for hemp concrete products with enhanced mechanical and thermal properties. Hemp-silica bio-composites were prepared by mixing hemp shivs with a two-component binder system composed of liquid sodium silicate and tributyl citrate (TBC). Compressive strength, thermal conductivity, moisture buffering value, cyclic moisture resistance and microstructure of hemp-silica composites were analysed, and the results were compared with those of hemp-lime concrete. Hemp-silica blocks with shiv-liquid sodium silicate mass ratio of 1:3.75 and TBC content of 37.5 wt% of sodium silicate dry matter produced a compressive strength of 0.56 MPa only after 3 days of drying and 1.92 MPa after 28 days. These were higher than hemp-lime blocks at the same density range. Hemp-silica panels showed a thermal conductivity of 0.101 W/mK and an excellent moisture buffering value of 3.49. Hemp silica formed an open porosity with large air gaps between the particles and a water-resistance silica-based layer on the shiv surface producing a higher moisture resistance compared to hemp-lime systems. This paper focuses on the development of a novel fast-drying binder system with a potential for use in conjunction with other lingnocellular plant aggregates to form low-carbon and efficient multifunctional building materials. • A novel quick-drying silica-based binder for hempcrete was developed. • Hemp-silica concrete showed enhanced mechanical properties compared to hemp-lime. • Hemp-silica concrete reached 0.56 MPa only after 3 days of drying. • Tributyl citrate improved the water resistance of sodium silicate binder. [ABSTRACT FROM AUTHOR]

Performance-based concrete design can accelerate the acceptance of emerging lower carbon concretes to reduce the environmental impact. A semi-adiabatic symmetric concrete prism experimental and analytical approach is proposed as a pathway for concrete thermal characterisation. The prism design promotes 1-D heat flow conditions using a single insulated specimen. The prism dimensions (700 mm ×100 mm ×100 mm) are rationalised to suit usage as a characterisation specimen and mix compositions that replicate those of in-situ concretes can be assessed. The experimental spatial and temporal thermal profiles of a CEM I mix and a high GGBS replacement mix were measured during hydration and through a step change in temperature in the hardened state. Thermocouples and a distributed fibre optic sensor along the central axis of the symmetric prism were used for this purpose. Multi-physics modelling provided a platform to address thermal measurement data uncertainty, extract fundamental concrete thermal parameters and gain insight into the heat generation and heat flow physics in the concrete prism specimens. The complete heat generation and maturity time histories were accurately modelled and 'concrete thermal footprints' derived. • Performance-based thermal assessment of concrete relies on characterisation testing. • A semi-adiabatic symmetric prism is used to derive concrete thermal footprints. • Heat generation and thermal properties are obtained from a single specimen. • The symmetric prism approach suits on-site application and a range of concrete mixes. • Embedded fibre optic or thermocouple sensors reveal internal temperature profiles. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the thermal behavior of composite building materials comprised of silt and flax fibers, considering various initial conditions. The experiments were conducted on flax fibers alone, examining factors such as moisture content variation, fibers arrangement, and density. Subsequently, the thermal properties of the earth-flax fiber composite were studied, taking into account the influence of water content and fibers mass content. The thermal properties of both flax fibers and raw earth-flax fibers composite specimens were determined using the experimental unsteady-state method. The results indicate that the thermal conductivity and heat capacity of flax fibers increase with density, temperature, and moisture content. Regardless of fibers density and arrangement of fibers, linear relationships have been established for both thermal conductivity and heat capacity as functions of temperature. Additionally, it was demonstrated that the heat capacity and the thermal conductivity increase with water content, regardless of the percentage of added fibers. Moreover, mixing randomly flax fibers with compacted raw earth material has improved the thermal properties of the composite. This improvement pertains to its insulating capacity, ability to store heat, and, subsequently, its contribution to the thermal comfort provided by such earth composite material when used as a building material. • Thermal conductivity enhances by increasing the moisture content and density. • The arrangements of fibers have highly influenced the thermal properties. • Linear relationships were established for the thermal conductivity and heat capacity. • The addition of flax fibers to raw earth improved the thermal properties. [ABSTRACT FROM AUTHOR]

High-strength thermal insulation mortar, with its excellent mechanical properties and thermal insulation performance, is commonly used in building structure insulation and reinforcement renovations. In this study, vitrified microbeads and expanded perlite (EP) were used as thermal insulation materials to create high-strength thermal insulation mortar. The effects of the replacement percentage of these materials (50%, 65%, 75%, and 80%) on the density, water absorption, porosity, compressive and flexural strength, and thermal conductivity of the mortar were studied. The results show that increased replacement percentages of vitrified microbead (EP) led to a decrease in the density of the mortar and an increase in the water absorption rate and porosity. Furthermore, when the replacement percentages were increased, the compressive and flexural strength and the thermal conductivity of the mortar were reduced. Comparative analysis of the pore structure of high-strength thermal insulation mortar using scanning electron microscopy and digital microscope revealed the influence of vitrified microbead (EP) on the internal pore structure of high-strength thermal insulation mortar. The influence coefficient (η s) of volume replacement percentage of insulation materials was introduced using the Hamilton and Crosser models. Furthermore, the prediction model of thermal conductivity of high-strength thermal insulation mortar was established under different volume replacement percentages of vitrified microbead (EP). The calculated values of the model matched well with the measured values, with the ratios of the calculated values of the model to the experimental ones ranging from 0.85 to 1.15. • The physical, mechanical, and thermal conductive properties of mortar are found to be influenced by the amount of insulation. • The prediction model of thermal conductivity of high-strength thermal insulation mortar is established. [ABSTRACT FROM AUTHOR]

The negative impact of glass fibre-reinforced polymers (GFRP), slag and fly ash on the environment has garnered significant attention; therefore, the aim of this study was to explore the possibility of replacing cementitious materials with GFRP powder, slag and fly ash to develop mortar with better thermal insulation and mechanical properties. The use of GFRP powder to replace cementitious materials was investigated. The experimental variables were the substrate, fly ash, and GFRP powder content. To analyse the mortar materials and specimens, various tests including X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and mechanical and thermal property testing were performed. The mortar with 20% GFRP powder using the ordinary Portland cement or alkali-activated slag as cementitious material exhibited excellent mechanical and thermal properties at 0.6 water-cement ratio. The use of fly ash as a substitute for cement resulted in a decrease in flexural strength by approximately 50%, compressive strength by 30%, and thermal conductivity by 66.3%. The use of fly ash and GFRP powder instead of cement reduced thermal conductivity of the mortar but decreased its flexural and compressive strengths by up to 40%. • Properties and microstructure of insulated concrete with GFRP powder were studied. • Test variables included the substrate, fly ash, and GFRP powder admixture. • Developed insulated concrete showed good mechanical properties. • GFRP powder used in concrete had excellent thermal insulation performance. [ABSTRACT FROM AUTHOR]

This article presents a new application of a well-known theory concerning mixing. The introduction of boundary conditions was proposed, which allowed the determination of a universal formula for the k parameter of the system. A graphical method for solving the problem has been proposed, which is supported by studies of the synthesis of rigid polyurethane foam. Mixing tests were performed using a variable ratio of the diameter of the stirrer to the diameter of the mixing chamber. Block-shaped samples were obtained, which were then characterized in terms of mechanical properties - compressive strength, brittleness, in terms of thermal properties - Thermogravimetric analysis, differential calorimetry, in terms of qualitative and quantitative structure studies using SEM images, and in terms of chemical analysis using FTIR. The proposed method for determining the boundary parameters of blending systems was proved to be applicable to polyurethane blending system. • Analytical considerations regarding the mixing process. • Proposing a new approach to determining important boundary parameters for the polyurethane mixing process. • Proposal to improve polyurethane blending processes to reduce the energy intensity of the process. • Effect of stirrer-to-vessel diameter ratio on the structure and properties of rigid polyurethane foam. [ABSTRACT FROM AUTHOR]

A detailed evaluation of alkali-activated fly ash-slag's (AAFS) mechanical and microscopic behavior characteristics under thermal cycling is crucial for its application in complex high-temperature environments. This study investigated the performance evolution and mechanism of AAFS materials under 60 ℃ thermal cycling from the aspects of quality, compressive strength, drying shrinkage, hydration products, and microstructure. It has the highest compressive strength at 60 thermal cycling, and the compressive strength will rebound and rise after 300 thermal cycling. The formation, decomposition, or restructuring of the gel phase of hydration products causes changes in internal pore characteristics, and the number and width of microcracks, thereby affecting macroscopic performance changes. It is found that in the complex high-temperature environment, the fly ash-slag mass ratio in the alkali-activated system should be 1:1, the most suitable alkali activator module is about 1.0, and the Na 2 O concentration is 4%⁓6%. • The highest compressive strength at 60 thermal cycling. • When the thermal cycling times reach 300, the compressive strength rebound increases. • In a complex high-temperature environment, the alkali-activated raw materials are not suitable for pure fly ash and slag systems. • The C-(A)-S-H gel phase is unstable under long-term cycling at 60 °C. • The fly ash-slag mass ratio in the alkali-activated system should be 1:1, the most suitable alkali activator module is about 1.0, and the Na 2 O concentration is 4%⁓6%. [ABSTRACT FROM AUTHOR]

Reducing the brittleness of oil well cement is of great significance to improve the durability of the cement sheath under complex loads and prolong the service life of oil and gas wells. To reduce the brittleness of oil well cement, this study used modified nano-SiO 2 as the emulsifier and an epoxy resin/polyamide system as the core material to prepare flexible composite microspheres (ERM-5, ERM-8, and ERM-10) with different core-shell ratios based on the Pickering emulsion method. The morphology, particle size, composition, thermal properties, hydrophilicity, and mechanical properties of ERM were characterized by SEM, laser particle size analyzer, FT-IR, XPS, TGA, interfacial tensiometers, and nanoindentation. The effects of ERM on the compressive strength and elastic modulus of cement stone were studied. The results showed that ERM had a regular spherical structure, and the median particle sizes of ERM-5, ERM-8, and ERM-10 were 30.8, 38.1, and 47.2 µm, respectively. The coating of SiO 2 improved the hydrophilicity and thermal stability of ERM. The elastic modulus of ERM-5, ERM-8, and ERM-10 were 3.04, 3.20, and 3.55 GPa, respectively. More importantly, the incorporation of ERM can effectively reduce the brittleness of oil well cement and improve its strain capacity under load. Among them, the peak strain of the cement sample containing 6% ERM-5 microspheres reached 0.81%, and the elastic modulus decreased to 4.8 GPa, which was 50.5% lower than that of the control sample (9.7 GPa). The pozzolana effect of nano-SiO 2 improved the binding ability of ERM to the cement matrix, which was conducive to the elastic deformation ability of organic core materials, thereby reducing the brittleness of cement. In addition, the debonding of nano-SiO 2 with cement or resin can further dissipate the load stress. Composite microspheres can synergistically exert the performance advantages of inorganic and organic materials, and the simple preparation process and convenient application method make it have good application prospects. [Display omitted] • SiO 2 /epoxy resin microspheres ERM were prepared by the Pickering emulsion method. • The properties of ERM microspheres are controlled by the core-shell ratio. • ERM microspheres effectively reduced the brittleness of cement stone. • The sample containing 6% ERM-5 has the highest deformation ability under load. [ABSTRACT FROM AUTHOR]

Seashells accumulate rapidly, particularly in coastal areas and in countries that consume a lot of seafood. In order to be recycled and used in ordinary building materials, we have carried out a study into the feasibility of using the seashells in plaster as a substitute and additive. Two cases of incorporation were carried out, the first involving the substitution of plaster by seashell powder in percentages (4%, 8%, 12%, 16% and 20% by mass), the second consisting of the use of the powder as an additive in percentages (2%, 4%, 6%, 8% and 10%). The compressive and flexural strength values are close to those of the control gypsum. However, the use of powder as a substitute can improve the thermal insulation and durability of the gypsum composite. [ABSTRACT FROM AUTHOR]

Recycled concrete powder (RCP) is a promising supplementary cementitious material, its application in thermal insulation materials is however very limited. In this study, the influence of RCP substitution on the properties of insulation mortars was investigated. The results showed that as the RCP content increased, the compressive strength and thermal conductivity of insulation mortars decreased by 39.8% and 16.8%, owing to the increasing volumes of porous paste and internal air voids. Note that the mortar containing a high content (50 wt%) of RCP struggled to meet the strength requirements of the specification. Therefore, CO 2 curing was further employed here to alleviate the strength loss and successfully increased the compressive strength by 11%∼38%. It was found that since the CaCO 3 particles formed and densified the microstructure (confirmed by the porosity test), the strength reduction derived from the RCP substitution was compensated for. Consequently, insulation mortars incorporating 50% RCP after CO 2 curing for 7 days exhibited satisfactory compressive strength (∼ 0.22 MPa) and relatively low thermal conductivity (∼ 0.048 W/(m∙K)). The mortars showed improved aesthetic appearance and excellent thermal insulation capacity in both hot and cold environments. This study proposed a successful approach to combining reutilization of RCP and CO 2 curing in insulation mortar generation, which effectively improved the sustainability of materials. • A novel and sustainable EPS insulation mortar is developed for energy-efficient buildings. • The synergistic influence of the RCP substitution and CO 2 curing duration is studied. • Remarkably low thermal conductivity is attained through the incorporation of RCP. • Excellent aesthetic appearance and thermal performance are achieved simultaneously. [ABSTRACT FROM AUTHOR]

A novel lightweight foamed cement-based electromagnetic wave (EMW) absorbing material (Density<0.5 g/cm3) is prepared using secondary aluminum ash (SAA) as a foaming agent and carbon black (CB) as an efficient EMW absorbent, providing a new way to recycle SAA. The pore structure parameters, reflection loss (RL), mechanical strength and thermal conductivity are systematically investigated. The experimental test results indicate that the pore structure of cement matrix prepared by SAA exhibits better EMW loss performance than those prepared by traditional foaming agent. The analysis of the pore structure images indicates that the average pore size is reduced, and pore size distribution shifts towards smaller sizes due to the addition of CB. Furthermore, the roundness of pores is increased due to the formation of more irregular pores. Increasing CB content and thickness can reduce RL, enhance absorbing performance at low frequencies, and broaden effective absorbing bandwidth (EAB). The absorbing performance was tested using the arch reflection method in the frequency range of 1.1–18 GHz, the excellent absorbing performance and the widest EAB (RL<−10 dB) reach −36.34 dB and 14.46 GHz, respectively, at a thickness of 4 cm. Benefiting from excellent pore structure, the foamed cement-based material also exhibits better mechanical strength, and good thermal insulation properties are maintained after adding CB. The compressive and flexural strength can reach 2.18 MPa and 1.02 MPa, respectively, while the thermal conductivity remains below 0.122 W/(m·K). • Lightweight cement-based absorber was firstly prepared using SAA as foaming agent. • The effect of CB on pore structure and EMW absorbing property is investigated. • EAB and minimum RL of the developed absorber reach 14.46 GHz and − 36.34 dB. • A new way to recycle SAA is provided. [ABSTRACT FROM AUTHOR]

The purpose of this study is to assess the effect of polyurethane solid-solid phase change materials (PUSSPCMs) and polyethylene glycol (PEG4000) on the thermoregulatory and rheological properties of asphalt, as well as their potential for regulating asphalt pavement temperature. The chemical and thermodynamic characteristics of PEG4000 and PUSSPCMs were investigated using infrared spectroscopy (FTIR), adsorption test, polarized light microscopy (POM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG), and atomic force microscopy (AFM). Meanwhile, the effects of PEG4000 and PUSSPCMs on asphalt road performance and micromorphology were determined by tests of thermoregulation, three major indexes, DSR segregation, and scanning electron microscopy (SEM). The results indicate that PUSSPCMs have no hydroxyl characteristic peaks of PEG4000 and isocyanate bonds after the complete reaction. PUSSPCMs exhibit better phase stability over PEG4000, the soft segment for thermal storage changes from crystalline to amorphous and is limited by the hard segment micro-region to maintain a stable solid phase. PUSSPCMs exhibit slightly weaker thermal storage properties than PEG4000, while the thermal stability and elastic modulus are stronger. PUSSPCMs-modified asphalt performs lower thermoregulation properties than PEG4000-modified asphalt, which improves with the increasing soft segments. Furthermore, the advantages of PUSSPCMs-modified asphalt are in terms of basic physical, rheological properties and storage stability. The micromorphology of PUSSPCMs-modified asphalt shows no visible cracks compared to PEG4000-modified asphalt and flattens with soft segment rises, which contributes to the thermoregulation and rheological properties of asphalt. • The phase change behavior, thermal storage properties, and mechanical properties of PUSSPCMs and PEG4000 are investigated. • The thermo-mechanical properties of PUSSPCM and rheological properties of PUSSPCM-modified asphalt are investigated. • The correlation of the thermo-mechanical properties of PUSSPCMs and PEG4000 with the thermoregulation and rheological properties of modified asphalt was analyzed. • Micro-morphological characteristics of PUSSPCMs-modified asphalt and PEG4000-modified asphalt are observed. [ABSTRACT FROM AUTHOR]

Geopolymers, characterised as customisable, environmentally friendly, and thermally robust materials, have yet to receive comprehensive studies on compressive properties in their high-temperature states. In this study, a sodium silicate-activated binary geopolymer with strength and elastic modulus increased in thermal environments above 100 ℃ was developed. Investigation of stress-strain relations, compressive strengths, strains at the compressive strengths, and elastic moduli was performed across temperatures ranging from 100 ℃ to 1000 ℃. The optimal geopolymer product showed substantial strength and elastic modulus enhancements at temperatures below 500 ℃, with elastic modulus decline above 500 ℃, indicating material deterioration. Thermal behaviour investigations and microstructure experiments were conducted to elucidate this mechanism. A positive correlation between hot-state density and mechanical properties was established. The geopolymers showed thermal shrinkage properties, aiding structure compaction with less density loss, which is advantageous for their mechanical properties below 500 ℃. Heightened chemical changes at 500–1000 ℃ led to pronounced property shifts, with product decomposition and ions diffusion causing more deterioration at 500–700 ℃. Initial crystal formation at 800 ℃ played a favourable role in the partial property recovery of the geopolymers. This study broadens the application scope of industrially derived geopolymers, fostering the creation of safer materials for structures vulnerable to heat exposure. ● Developing a binary geopolymer with increased strengths in thermal environments. ● Increased elastic modulus obtained in thermal environments below 500 ℃. ● A sharp decrease in elastic moduli occurred above 500 ℃. ● The product decomposition and ions diffusion caused more deterioration at 500–700 ℃. ● Partial property recovered above 800 ℃ due to chemical transformations. [ABSTRACT FROM AUTHOR]

Concrete infrastructures, such as high-speed railway subgrades, are vulnerable to frost heave in cold regions. Multi-stage phase change material (PCM) aggregate concrete can alleviate frost heave by thermal regulation. This study explored the effect of replacing coarse aggregate with multi-stage PCM aggregate at 0%− 100% on concrete. Firstly, the compressive strength and splitting tensile strength of PCM aggregate concrete were evaluated. Then, the influence of substituting PCM aggregate on the thermal properties was investigated, including thermal conductivity, thermal diffusivity, volumetric heat capacity, and time-temperature curve. Subsequently, the changes in the pore structure were characterized by using a combination of nuclear magnetic resonance (NMR) and computerized tomography (CT). Finally, the interface transition zone (ITZ) of natural aggregate and PCM aggregate was evaluated by using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results show that the mechanical properties of concrete decrease after the addition of PCM aggregate, but its thermal properties improve. This improvement is not only related to the PCM aggregate but also to the increased pores. It has been confirmed by NMR and CT analysis that the replacement of PCM aggregate leads to an increase in both pore volume and pore number. Only the macropores with a volume larger than 108 μm3 may have an impact on mechanical and thermal properties, although their quantity only accounts for 2%. The SEM and EDS results show that there are no obvious cracks in the ITZ of PCM aggregate, indicating that the PCM aggregate has better compatibility with the cement matrix. Considering the mechanical properties, thermal properties, and porosity, the replacement of 60% PCM aggregate is reasonable in concrete, which provides a theoretical basis for multi-stage PCM aggregate concrete application in cold regions. • The strength of PCM aggregate concrete is descending. • The incorporation of PCM aggregate increases the thermal performance. • The pores increase after the incorporation of PCM aggregate. • A few macropores affect the performance of concrete. • The ITZ of PCM aggregate concrete is not the weakest area. [ABSTRACT FROM AUTHOR]

In the present study, a novel hybrid composite product has been prepared by using plain woven jute fabric as one component and short bamboo fiber reinforced thermoplastic (BPC) as the second component. BPC was prepared using a co-rotating twin screw extruder and the same was used as a resin matrix for preparing hybrid jute fabric composite (JFC) via layering method. In this work, the effect of polymer type i.e., polypropylene (PP) and high-density polyethylene (HDPE), coupling agent (CA) and bamboo fiber content (10%, 30%, and 50%) in the BPC on physical, mechanical, water absorption and thermal properties of JFC has been investigated. The properties of BPC bonded JFC were compared with similarly produced composites using neat polymers. Mechanical properties and water absorption behavior in BPC bonded JFC were significantly improved with increased proportion of bamboo fibers in BPC, more specifically up to 30% fiber reinforcement. Also, the properties in fabricated composite were significantly higher in samples added with CA. Experimental results showed that flexural strength in 3L/JFC prepared with 30%-BPC was increased by 35% and 50%, as compared to similarly produced composite from neat PP and HDPE, respectively. Similarly, compared to neat PP and HDPE based JFC, the flexural modulus of 3L/JFC prepared with 30%-BPC was increased by 79% and 120%, respectively. Scanning electron microscopic images showed the evidence of physical bonding between BPC matrix and jute fabric in the form of mechanical interlocking. In general, the properties of BPC bonded hybrid JFC were significantly higher than those of similar composites made from pure polymers. [Display omitted] • Novel composites were prepared by embedding woven jute fabric with bamboo polymer composite (BPC). • The developed composite i.e., woven jute fabric composite (JFC) bonded with BPC exhibited improved physical and mechanical properties compared to neat polymer bonded JFC. • Presence of coupling agent enhanced the physical and mechanical properties of the JFC. • SEM characterization of the composites indicated uniform flow of BPC in the free space between woven jute fabrics resulting in good mechanical bonding. [ABSTRACT FROM AUTHOR]

Ultra-high-performance concrete (UHPC) is increasingly used for bold structures worldwide due to its exceptional mechanical properties, but its fire performance is not well known. Standards and literature provide limited information and data on the thermal-physical properties of some UHPC mixes exposed to high temperatures. This study aims to partially fill this gap. The thermal parameters of UHPC were determined experimentally and then compared with another UHPC mix proposed in the literature and also with those defined in EN 1992–1.2 for normal strength concrete (NSC). To understand the thermal diffusivity (i.e., the thermal field) of UHPC and NSC structures, a FEM -based numerical application was performed using Abaqus software, assuming the thermal-physical data of UHPC and NSC. Cross sections with the experimentally determined UHPC properties showed quite similar behavior to NSC. However, using the UHPC data proposed in the literature, the thermal diffusion in the cross-section appeared to be much more severe. The thermal-physical properties of UHPC can vary greatly depending on the mix design, with UHPC cross-sections exhibiting a maximum 110% greater thermal field than those simulated with NSC properties. • Definition and proposition of thermal and physical parameters of UHPC at high temperatures. • Thermal conductivity, thermal diffusivity, specific heat of UHPC in fire. • Thermal field of UHPC structures in case of fire. • Comparison between UHPC and NSC beams in fire. [ABSTRACT FROM AUTHOR]

Incorporation techniques of phase change materials (PCM) in cementitious composites have a significant influence on thermal properties. This study investigated the thermal behavior of low-temperature PCM when subjected to varying temperature change rates and pore confinement inside the porous network of lightweight aggregates (LWA) and encapsulation using melamine-formaldehyde-based polymer. Three categories of thermal energy storage (TES) specimens were prepared: (i) Bulk PCM (i.e., liquid PCM), (ii) micro-encapsulated PCM (MPCM), and (iii) four different LWAs infused with PCM (PCM-LWA). The thermal properties of small-scale individual TES specimens were analyzed using a low-temperature differential scanning calorimeter (LT-DSC) to evaluate the effect of ramp rates. Dynamic vapor sorption (DVS) analysis was utilized to characterize the pore structure of LWAs. LT-DSC results show that undercooling of the PCM significantly increases with the rise in ramp rate for all the specimens; temperature change rate affects the nucleation and crystallization growth process during the phase transition. Pore structure characterization of LWAs indicates that the majority of the pores (> 92 %) were larger than 17.3 nm (i.e., macropores). Confined liquid properties are subjected to modification due to interaction with the confining surfaces, as explained by Gibbs-Thomson theory. PCM incorporated in the LWA porous network experienced variable degree of supercooling during phase transition; magnitude of confinement pressure is dependent on the pore diameter, structure, and tortuosity. Experimental evidence suggested that PCM-LWA will exhibit gradual expulsion of enthalpy of fusion over a larger temperature range (i.e., ∼−5 °C to 4.28 °C) in comparison to MPCM (i.e., ∼4.28 °C). • Effect of temperature change rate on phase transition properties of PCM. • Effect of LWA pore network confinement on phase transition properties of PCM. • Thermal efficiency of latent heat storage specimens. • Correlation of pore size to melting temperature using Gibbs-Thomson theory. [ABSTRACT FROM AUTHOR]

In the field of material science, foaming agents common are commonly used for enhancing the thermal insulation and phase change materials (PCM) for heat storage. However, PCM tends to agglomerate in the cement slurry with the directly addition, presenting an obstacle to effective dispersion. Moreover, the addition of PCM leads to rapid defoaming. To overcome this issue, a novel nanoparticle-stabilized foam was designed in this study to create a three-component system that enhances the interaction of viscosity modifiers, surfactants, and foam stabilizers. The effect of cement density on thermal insulation was evaluated by analyzing thermal conductivity and heat transfer performance tests, as well as exploring the mechanical properties of the cement-based materials. Scanning electron microscope (SEM) images show that the foam designed in this study remarkably promotes the dispersion of PCM microcapsules, indicating the bridging interactions of foam in the cement paste. The result shows that the thermal conductivity of foam cement with 15 vol% PCM microcapsules drops from 0.11 W/m·k to 0.07 W/m·k compared to that without PCM addition, with a dry density around 600 kg / m 3. Furthermore, the specimens with the addition of PCM achieve the endothermic and exothermic peaks under experimental images. This discovery is of great significance to heat absorption ability of low-density concrete, where the addition of PCM leads to a slower foam bursting under the nanoparticle-reinforced foam system. The dispersion and connectivity of foams, as well as the physical characteristics of PCM, provide new perspectives for coexistence in a relatively stable system in this way. • Nanoparticle-stabilized foam remains stable within the cement slurry. • Stable foam contributes to the low thermal conductivity and superior insulation performance of foam cement. • The sustainable and environmentally friendly energy-saving effects of phase change materials microcapsules in foam cement. • A novel lightweight and eco-friendly cement with thermal regulation capabilities. [ABSTRACT FROM AUTHOR]

• Biochar was used as an eco-friendly fire retardant that effectively blocks heat transfer. • Thermal stability at high temperature was improved as the content of biochar increased. • A fire-resistant building material was manufactured through the cone calorimeter test. • Post-biochar systems have successfully improved the fire performance of bio-building materials. In an environment that emphasizes ecological sustainability, there is increasing interest in the development of bio-building materials to achieve carbon neutrality. Among bio-building materials, plant-based materials must also consider improving fire resistance. In this study, we developed composite materials with improved fire resistance by adding 0 %, 5 %, and 10 % biochar to bio-materials. A clear improvement in fire resistance was observed in the composite material (CB10) added with 10 % biochar. Through TGA analysis, thermal stability was improved by about 27.6 %, and through cone calorimeter testing, it was confirmed that the peak heat release rate was reduced by 34.5 %. The time to reach the maximum value was also delayed from 25 s to 45 s. This study confirmed that biochar is an eco-friendly fire retardancy that acts as a barrier against heat and oxygen, and that bio-materials can also stably improve fire resistance. [ABSTRACT FROM AUTHOR]

• Silica aerogel granules were replaced by quartz sand of 0 to 4.5 wt% to produce lightweight cement-based composite mortars. • SAG has increased the water absorption and porosity of the mortar, while reduced compressive strength and hardened density. • Pores increased with increase in aerogel, SAG tend to agglomerate, and pores accumulate around the aerogel particles. • SAG significantly decreased thermal conductivity from 0.772 to 0.155 W/mK. • SAG also reduced thermal diffusivity and heat storage, and increased specific heat. It has been discovered in recent years that the use of silica aerogel in cement-based materials contributes to the thermal insulation properties of the materials, and studies on this subject have gained importance. However, it was determined that the studies mostly remained at the level of the thermal conductivity coefficient and the main physical and mechanical properties of the materials. In this study, a comprehensive research was carried out with the replacement of micro-sized aerogel particles with quartz sand in different ratios (0, 1, 1.6, 2.4, 3.2, 4 and 4.5 wt%) in lightweight cement-based composite mortar (LCCM) combinations. Specifically, the effect of silica aerogel granules (SAG) on flowability, fresh and hardened densities, porosity, water absorption, compressive strength, macro/microstructural properties (by optic microscope, SEM, XRD analysis), thermal conductivity, specific heat, thermal diffusivity and heat storage capability of LCCMs were investigated. While SAG could increase the flowability (up to 8.4 %) at low using rates, it decreased it at higher rates. It is very effective in reducing fresh and hardened densities. However, it highly increased porosity and water absorption, and greatly decreased compressive strength. On the other hand, generally the poor interfacial properties of the cement matrix and the aerogel were moderately improved in this study. The lowest thermal conductivity was determined as 0.155 W/mK in the highest SAG usage. SAG increased specific heat, decreased thermal diffusivity and decreased heat storage capability of LCCMs up to 45.23 %, 63.49 % and 46.32 %, respectively. As a result of the study, aerogel has been identified as a very suitable material that can be used to highly improve thermal properties in LCCMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sandwich panel with face sheet of CSB and core with PU and PU replaced with CH were studied. • PU replaced with CH at 10, 20, 30, 40 and 50 %, and material characterizations, mechanical, durability and acoustic property, thermal conductivity test were conducted. • Incorporation of CH at 10 and 20% with PU shows enhancement in various properties. • Regression analysis was conducted to validated by the suitable R2 threshold accuracy as R2 > 0.90. As the need for a sustainable solution increase, waste materials are gaining popularity in building applications to reduce the environmental impact. This study aims to utilize the waste Coconut Husk (CH) and Calcium Silicate Board (CSB) in a sandwich panel where Polyurethane Foam (PU) is used as a binding material which consists of A (isocyanate) and B (polyol) with a mixing ratio of A: B at 1:1.2. CH is obtained as a residue from the production of coconut shells aggregate. The PU has been replaced with CH at 10, 20, 30, 40 and 50 %, to identify the optimum replacement level. Sandwich panels of dimension 30 × 30 cm with a core thickness of 2 and 3 cm was prepared and tested to categorize their mechanical properties, thermal properties, durability properties, characterization study and sound absorption coefficient. The results show that the PU replaced with 20 % of CH has higher compression and flexural properties, owing as an optimum percentage. The inclusion of CH in the PU reduces the cell size and yields a significant improvement in acoustic behavior up to a frequency of 1600 Hz. The regression model was analyzed with the experimental data and validated by the suitable R2 threshold accuracy as R2 > 0.90. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermoset composites prepared via ultrasonicator probe-assisted wet layup method. • Minimal water absorption for loofa fiber-Al-SiC polymer hybrid composites observed. • Composites were thermally stable up to 436 °C from TGA results. • ANN technique applied to optimize the best composite material. • One-way ANOVA technique used to check the significance at 95% confidence level. The physical, mechanical, and thermal characteristics of loofa fiber-alumina (Al 2 O 3) and loofa fiber-aluminum silicon carbide (Al-SiC) reinforced with epoxy, vinyl-ester, and polyester hybrid composites were experimentally studied. The polymer hybrid laminates were fabricated using an ultrasonication probe-assisted wet-layup technique. The outcomes show that flexural, impact, and tensile characteristics were higher for loofa fiber-Al-SiC reinforcement than other samples due to minimal voids and uniform dispersion of fillers within the matrices as observed from scanning electron microscope (SEM) images. Minimum water absorption and thickness swelling characteristics were examined for the composite specimen reinforced with loofa fiber-Al-SiC fillers. Thermo-gravimetric analysis (TGA) was performed, and the laminate was observed to be thermally stable up to 436 °C. Also, forecasting models were simulated using an artificial neural network (ANN) to perceive schemes in data by varying certain factors. The outcomes collected signified that loofa fiber-Al-SiC-based laminate could substitute traditionally applied materials and provide real-world directions. A one-way ANOVA (Analysis of Variance) technique was performed to check the significance between the physical, mechanical, and thermal characteristics of developed polymer hybrid composites and found significant under a 95 % confidence level. Based on the results, the loofa fiber-Al-SiC reinforced polymer hybrid laminate exhibited improved tensile, impact, and flexural characteristics along with remarkable thermal stability, recommends multi-faceted applications in industries demanding lightweight yet strong materials like automotive and aerospace field, where structural integrity and decrement in weight are dominant. [ABSTRACT FROM AUTHOR]

• Phenolic resin is used as an insulation modifier for geopolymer for the first time. • Phenolic resin can increase the porosity of fly ash geopolymer. • Phenolic resin can reduce the porosity of nanopores but increase more micropores. • Phenolic resin narrows the throat of the ink bottle pores. • An iterative method related thermal conductivity prediction method is proposed. Phenolic resin has been widely used owing to its excellent thermal insulation performance. However, the application of phenolic resin in the field of geopolymer remains unexplored. Here, the foamed fly ash geopolymer samples with high porosity were prepared using phenolic resin for the purpose of foaming materials. The thermal insulation properties of these samples were evaluated by Transient Plane Source Method, and the effect of phenolic resin on pore characteristics was investigated by Mercury Intrusion Porosimetry (MIP), aim to explore how phenolic resin affects the thermal conductivity by changing the pore characteristics of geopolymer. In addition, considering that the internal gas thermal conductivity of pores with different pore sizes is also different (Knudsen effect), in order to predict the thermal conductivity more accurately, this research proposes an iterative calculation method to establish a thermal conductivity model. The results show that phenolic resin can improve the thermal insulation effect of geopolymer, and the minimum thermal conductivity of the sample is 0.17 W/m·K. In addition, according to the test results of MIP, it can be found that phenolic resin mainly promotes the porosity of micron pores (>1 μm) whereas there is slight inhibition on nano pores (<1 μm), but the beneficial effect of the increase of micron-sized pores (>1 μm) on the thermal insulation performance of geopolymer is greater than the negative influence effect of the disappearance of nano pores. Moreover, according to the results of MIP, phenolic resin can narrow the throat in the pore of the ink bottle, limit the thermal convection of the gas between the pores, and reduce the thermal conductivity. Finally, the newly modified Russell model considering the Knudsen effect can effectively predict the thermal conductivity by using the experimental data. This study provides a new method to improve thermal insulation performance of geopolymers and offers a new building insulation product. [ABSTRACT FROM AUTHOR]

• Post-curing may occur with high temperature immersion. • Resin strength tends to increase and then decrease. • The DIC clearly reflects the strain during the stretching of the resin. • DTA shows that the thermal properties of the resin are also unaffected. • DMA indicates that secondary fronts occur at high temperatures. Fibre-reinforced polymer (FRP) tendons have excellent mechanical properties and corrosion resistance and are widely used in concrete structures; however, corrosion deterioration of FRP tendons is a serious problem in a highly alkaline concrete environment owing to the hygrothermal ageing effect of the resin. Accordingly, this study investigated the macro and micro properties evolution of epoxy resin in a simulated concrete pore solution at different temperatures. The results showed that the resin properties deteriorated significantly under long-term hygrothermal immersion. However, short-term high-temperature soaking caused some of the resin to undergo post-curing, improving its properties. [ABSTRACT FROM AUTHOR]

• Properties of alkali-excited fly ash aerogel foam concrete were studied. • The microstructure of alkali-excited fly ash aerogel foamed concrete was analyzed. • Test variable included aerogel particles, fly ash, foam and polypropylene fiber. • Developed concrete exhibited excellent thermal performance and mechanical strength. • Aerogel used in concrete had excellent thermal insulation performance. With increasing focus on low-carbon energy conservation and environmental protection, there is a need to consider all aspects of life in future developments. To meet the concept and requirements of energy conservation and environmental protection in the building industry, we have developed alkali-excited aerogel-foamed concrete that exhibits excellent thermal insulation performance and mechanical strength. The variables involved in its production include fly ash, foam, aerogels, and polypropylene fibres. In this study, the microstructure and mechanical and thermal properties of alkali-excited fly ash aerogel foam concrete was analysed. The results indicated that fly ash can replace a portion of the cement, resulting in a reduction in the thermal conductivity of the concrete. The addition of aerogels and foams to the concrete can significantly decrease its thermal conductivity. Specifically, when the aerogel content reaches 12 % and the foam content reaches 75 %, the thermal conductivity of the concrete decreases from 0.498 W/m·K to 0.183 W/m·K and 0.19 W/m·K, respectively. However, this decrease in thermal conductivity comes at a cost of approximately 50 % reduction in the flexural and compressive strengths of the concrete. The findings reveal that the aerogel has excellent thermal insulation performance similar to that of the foam, but it has little influence on the mechanical properties of the concrete. Additionally, an increase in the polypropylene fibre content significantly improves the mechanical properties of alkali-excited fly ash aerogel concrete, but the thermal properties of the concrete remain mostly unaffected. [ABSTRACT FROM AUTHOR]

• Vulcanized Eucommia ulmoides gum modified asphalt made from natural plant materials was created. • The optimal preparation parameters of vulcanized Eucommia ulmoides gum modified asphalt were determined. • Clarified the relationship between the dosage of Eucommia ulmoides gum and the optimal dosage of sulfur. • The modification mechanism of vulcanized Eucommia ulmoides gum modified asphalt is clarified from the microstructure. • The combustion products of vulcanized Eucommia ulmoides gum modified asphalt were clarified. In this study, a vulcanized Eucommia ulmoides gum modified asphalt (VEUGMA) was prepared using a natural plant-based renewable rubber Eucommia ulmoides gum (EUG) as the matrix. The preparation process and microstructural and thermal properties of VEUGMA were investigated. The results showed that the optimum shearing time for preparing VEUGMA was 45 min, and the optimum development time was 120 min. Moreover, the EUG dosage follows a monotonically decreasing linear relationship with the optimum sulfur dosage. The VEUGMA exhibited a preferable corrugated network structure, and the vulcanization process of EUG in asphalt can be divided into three stages: slight crosslinking, deep crosslinking, and supreme crosslinking. The X-ray diffraction pattern displayed that only new diffraction peaks of ZnO appeared in the VEUGMA, and the EUG and asphalt exhibited better compatibility under the action of vulcanization aids. After EUG was vulcanized in asphalt, the aromatic ring hydrogen in the asphalt was replaced by aliphatic chains. The VEUGMA exhibited a lower glass transition temperature that suggests a better low-temperature crack resistance. Two maximum decomposition temperatures were noted in the thermal decomposition process of VEUGMA. Moreover, the main gases released were CO 2 , CO, CH 4 , SO 2 , NO 2 , and NO; of which, CO 2 and CO exhibited the highest content, whereas the inferior emissions of SO 2 , NO 2 , and NO, can be ignored. The VEUGMA can effectively reduce the release of CO 2 and CO but has no significant effect on the release of CH 4. Further, VEUGMA demonstrated a smaller storage modulus (E'), loss modulus (E"), and loss factor (tanδ), which suggested better flexibility at low temperatures. Therefore, this work demonstrated the preferable modification effect achieved by adding 3.5 wt% EUG and 6 phr (parts per hundred parts of resin) sulfur to the matrix asphalt. [ABSTRACT FROM AUTHOR]

• Mechanical and thermal properties of straw boards with high densities are studied. • Tensile strength prediction method of straw boards is proposed. • Correlation between thermal conductivity and density of straw boards is revealed. • Feasibility of using straw boards for load bearing and insulation is verified. • Wheat straw strand board is identified as transversely isotropic material. Straw is an environmentally friendly, cost-effective, and abundant raw material for building boards. To assess the feasibility of using straw boards in building envelops, such as being alternative sheathing panels in light-gauge steel-framed members, for instance, walls and floors, both the mechanical and thermal properties of straw boards with high densities were investigated. The straw boards involved in this study include five wheat straw strand boards (WSSB12, WSSB15, WSSB18, WSSB25, and WSSB30) and a paper straw board (PSB58) named with a combination of the respective board type and thickness. Among them, the WSSBs are a type of straw composite, while the PSB is an improved straw bale with sheathing paper, which is mainly for enhancing the board integrality. Moreover, the former is composed of smashed straw fibers and isocyanate resin and has higher densities, while the latter is without using any artificial binders. Mechanical properties, including compression, tension, and bending properties, were investigated by tests and a proposed prediction method of tensile strength. In the experimental studies of compression properties, the failure modes, characteristics of load-deformation curves, and the differences in material directivity were analyzed and discussed. The results show that the WSSBs were considered to be transverse isotropic material with brittle characteristics in the plane. Then, the experimental studies of bending properties were carried out, and the results show that the bending strength is less than the compressive strength for WSSBs, while the bending strength of PSB is greater than its compressive strength. And the bending elastic modulus and the compression elastic modulus are close for either the WSSBs or the PSB. Furthermore, finite element models of the bending test specimens using the user material subroutine UMAT were developed to predict the tensile strength f t , and the constraint checks were conducted. It is verified that the prediction results of f t are believable, and the prediction method proposed is feasible. For the thermal properties of straw boards, tests were performed using the temperature control box - heat flux meter method, and the thermal conductivity λ was mainly focused. It is found that a significant linear correlation exists between the density ρ and λ , and the proposed fitting formula can be used to predict the thermal conductivities of such materials. Finally, brief comparisons of the mechanical and thermal properties between the straw boards and the oriented strand boards (OSBs) were conducted, and the feasibility of applying straw boards in building envelops, such as alternative sheathing panels with load bearing and insulation demands was verified. This study contributes to popularizing the application of straw boards in engineering structures by a compromising consideration of mechanical and thermal properties, which plays a positive role in the development of green buildings. [ABSTRACT FROM AUTHOR]

• Wax additives, except MS, improve the workability of bitumen. • Wax additives other than SL harden the bitumen and improve rutting resistance. • The chemical interaction between D wax and bitumen is more pronounced than other wax additives. • The effect of wax-based additives on the thermal behavior of bitumen is negligible. • The effect of wax-based additives on the mechanical properties of bituminous mixtures differs according to the type of aggregate used. Although the use of waxes in bitumen modification is not new, the effect of waxes on bitumen and bituminous mixture performance is still a complex subject of debate. This study was carried out to address this complexity and to comprehensively demonstrate the effect of wax-based additives on bitumen and bituminous mixtures. In this context, the systematic quantitative literature review (SQLR) method, which is more objective than the verbal approach, was adopted, and the results were systematically compared based on the numerical data obtained from the studies in the literature. The effect of waxes on the physical, rheological, chemical, and thermal properties of bitumen and the performance characteristics of bituminous mixtures have been evaluated in detail. [ABSTRACT FROM AUTHOR]

• Effect of SP and activation by RPA on structure of cement stone is revealed. • Increase the early strength of concrete, obtained by activation in RPA is established. • High physical properties of concrete are due to improved structure of cement stone. • Mineral content of hydration products contributes to the acceleration concrete curing. The novelty of the paper is to identify the scientific patterns of the influence of naphthalene formaldehyde and polycarboxylate superplasticizers during the activation process cementitious suspensions by the rotary pulsation apparatus (RPA), which have an energy density of 25 KW/m3 on the hydration mechanism and the structure of the cement stone. Cementitious suspensions obtained by mechanochemical activation in liquid state were prepared as novel compositions, on the basis of which concretes with high early strength are created. The strength characteristics of concrete mixes were researched by a series of tests (compressive strength, prism strength, flexural strength). In addition, the durability characteristics (frost resistance, sulfate resistance, water impermeability) were determined by standard techniques, confirm the creation of durable composites with high exploitation properties. Besides, the microstructural, morphological and thermal properties of such concrete at 28 days of curing were determined. For the first time, scientific data were obtained on the properties of cementitious suspension and concrete based on it, obtained by mechanochemical activation in an aqueous medium in the RPA with superplasticizers having different chemical bases. The results indicate that the mechanochemical activation of cementitious suspension by the RPA with the addition of Relamiks T-2 superplasticizer contributes to the improvement of the physicomechanical properties of concrete: the elastic modulus increases by 20%, flexural strength by 54%, prism strength by 67% compared to the control composition having the elastic modulus 33.57 GPa, flexural strength 5.41 MPa and prism strength 32.66 MPa. [ABSTRACT FROM AUTHOR]

• Different PAL materials and methyl palmitate (MPA) were used to prepare the composite MPA/PAL. • Acid treatment can remove the impurities inside the crystal bundles and then form a highly porous structure. • The values of freezing latent heat for MPA/Raw PAL, MPA/H+-PAL and MPA/OPAL were 51.31 J/g, 96.10 J/g and 81.96 J/g. • The H+-PAL/MPA composite has good thermal reliability after 300 times thermal cycling test. In this study, palygorskites (PALs) including raw PAL, acid-activated PAL and organic PAL were using as carrier to prepare methyl palmitate (MPA)/PAL composite phase change materials (PCM) by vacuum impregnation method (VIM) and direct impregnation method (DIM), respectively. The microstructure, thermal property and thermal stability of MPA/PAL composite were investigated. Scanning electron microscopy and N 2 adsorption-desorption measurement results of PAL indicated that acid treatment can remove the impurities inside the crystal bundles and then form a highly porous structure. The MPA was well incorporated into the holes and surface of PAL. The MPA/PAL composite prepared by VIM exhibited higher absorption ratio (46.32%) than that of DIM. The values of freezing latent heat for MPA/Raw PAL, MPA/H+-PAL and MPA/OPAL (prepared via VIM) were 51.31 J/g, 96.10 J/g and 81.96 J/g, respectively. The phase-change temperature of MPA/PAL composites was range from 22.29 °C to 24.5 °C. Moreover, the H+-PAL/MPA composite had good thermal reliability after 300 times thermal cycling test. Therefore, the MPA/PAL composite was an effective building material for reducing energy consumption. [ABSTRACT FROM AUTHOR]

• Lightweight concrete containing scrap-tyre-rubber-based aggregate. • A wide set of structural, mechanical, thermal and hygric properties. • Improved thermal performance, approved thermal stability up to 300 °C. • Unaffected water transport parameters, while water vapour transition increased. • Non-bearing lightweight material having benefits to the environment and economy. Increasing amount of waste tyres represents a global problem as tyres can pose a risk to the environment if not treated properly. Recycling of waste tyre rubbers in civil engineering as aggregate in cement concrete can be an effective environmental and economic approach. As problems associated with the use of waste tyre rubber in concrete production are not completely understood, a detailed analysis of rubber concrete prepared from used tyre rubber-based aggregate involving testing of its mechanical, basic physical, microstructural, hygric and thermal properties, and behaviour after exposure to elevated temperatures is presented in this paper. Testing of mechanical performance included measurement of compressive strength, flexural strength, secant and dynamic modulus of elasticity. Thermal conductivity was determined in the dependence on moisture content, from the dry to fully water saturated state. Dry volumetric heat capacity was also tested. Specific attention was paid to the hygric performance of rubberized concrete that was characterised by the water and water vapour transport parameters. Investigation of concrete properties after its thermal exposure included testing of mass loss, mechanical resistance, bulk density, and thermal conductivity that was tested as property having direct relation to concrete structural parameters. The use of scrap-tyre-rubber aggregate resulted in a decrease of the unit weight, worsening in mechanical parameters and a significant reduction in thermal conductivity of prepared rubberized concrete. Rubber-based aggregate almost did not affect water transport properties, while water vapour transport properties increased with rubber amount in the mix. No significant changes on concrete characteristics related to rubber incorporation occurred at temperatures up to 300 °C. However, after exposure to 400 °C, significant changes in measured concrete properties were observed, which was in line with the thermogravimetric analysis of the used tyre-based rubber. Nevertheless, based on rubberized concrete functional properties at common ambient conditions it can be considered as an alternative lightweight material, bringing benefits to the environment and economy as it is produced from crap available in a large amount and at a negligible cost. [ABSTRACT FROM AUTHOR]

• Corn stalk concrete using MPC and OPC were studied. • Effect of temperature on thermal properties of two biocomposites was studied. • MPC binder is more suitable for producing plant aggregate concrete. This paper reports a comparative investigation of two new corn stalk (CS) biocomposites based on magnesium phosphate cement (MPC) and ordinary Portland cement (OPC). Two composites with identical corn stalk contents and different binders were prepared. The porosity, water absorption, drying kinetics, compressive strength and thermal properties of the biocomposites were measured. The experimental results show that the lower open porosity of the CS-MPC concrete results in lower water absorption and weaker evaporation performance. In addition, the open porosity and closed porosity play important roles in the effect of temperature on the thermal properties in the dry state and moist state. The dry and moist thermal conductivities of CS-MPC concrete is slightly higher than that of the CS-OPC concrete, which can meet the thermal insulation requirements. Due to the excellent bonding between the MPC binder and corn stalk plant aggregates, the compressive strength of CS-MPC concrete is significantly higher than that of CS-OPC concrete. These results indicate that MPC binder is more suitable for producing plant aggregate concrete. [ABSTRACT FROM AUTHOR]

• The technical feasibility for manufacturing fired clay bricks by adding vine shoots has been tested. • The influence of particle size and percentage of vine shoot replacement has been discussed. • The percentage of vine shoot replacement highly impacts on mechanical and thermal properties. • The influence of particle size on mechanical properties increases by increasing percentage of additive. • The proposal environmental impact seems to be positive but further assessments must be conducted. For decades, the construction industry has focused on developing new materials to minimise environmental impact and improve building insulation envelopes. The use of certain wastes as additives for construction materials (e.g. concrete, clay, steel) has been shown to be a feasible alternative that may improve both the current waste management strategy and the properties of construction materials. Among others, the fired clay brick (FCB) industry has been highlighted as an optimal sector for incorporating such residues, due to the large amount of mass flow involved, the use of firing temperatures above 900 °C and the observed positive effects of FCB thermal conductivity (TC) when organic residues are added. Although the properties of fired clay are closely related to the firing curves and the mineral and chemical composition of raw materials, the effect of particle size is also a key factor that directly impacts on the economic and technical feasibility. This paper therefore assesses the addition of wood chips from pruned grapevine shoots as an additive for manufacturing FCBs, and considers three particle sizes (up to 0.5 mm, above 1.5 mm and between 0.5 and 1.5 mm) and variations in the added percentage on a dry basis. Several samples were tested in order to determine the mechanical and thermal behaviour of FCBs, and it was concluded that the maximum of 10% wood chip content is limited by both the compressive strength values and the water absorption. At this percentage, TC is reduced by up to 50%. The particle size seems to have no effect on the thermal properties, but gives rise to significant variations in terms of the mechanical response. [ABSTRACT FROM AUTHOR]

• Thermal resistance and microstructure of mortars containing CWP were examined. • The addition of CWP improved the mechanical strength of mortar specimens heat-treated. • Increasing temperature made a decrease in cracks extensions with using CWP. • Temperature caused the micrograph of mixes containing CWP showed denser microstructure. • Porosity of specimens containing higher content of CWP decreased. In the present study, thermal and mechanical characteristics of cement mortar incorporating Ceramic Waste Powder (CWP) as cement replacement were examined. The cement of the mortar mixes has been replaced with CWP which was provided from Almas-Kavir Company (Iran) in amounts of 5%, 10%, 15%, 20% and 25% (by weight of cement). The mortar specimens were cured in water for 28 days, and then the hardened specimens were exposed to temperatures of 200 °C, 400 °C, 600 °C, and 800 °C. This paper represents the thermal performance of CWP as cement replacement based mortar, including the mechanical strengths, mass loss, dry bulk density, ultrasonic pulse velocity and total porosity of the cement mortars. The X-Ray Diffraction (XRD) and Scanning Electron Micrograph (SEM) analyses of mentioned mortars have been also measured to explore the microstructure of heat treated specimens. Additionally, surface cracks of the mortar specimens were examined. Experimental results explain that specimens containing CWP exhibit higher compressive and flexural strengths than control specimens at elevated temperature. The study has also shown that mortar specimens containing CWP improved the thermal resistance of mixes. The XRD analyses showed that the mixes containing CWP have a lower intensity of portlandite peaks than the control mix, and SEM images explained that using CWP reduced the porosity. It should be mentioned that incorporating CWP as cement replacement improved several characteristics at elevated temperatures. [ABSTRACT FROM AUTHOR]