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Highlights • Lime sludge utilization in concrete, mortars, fired bricks, ceramics and cement. • 10–30% cement replacement in concrete and mortars by lime sludge is optimum. • 25–30% replacement of fine aggregates by lime sludge is optimum. • Bricks and ceramic production with lime sludge conserves less energy. • Lime sludge eco clinker synthesizes with less carbon footprint and temperature. Abstract This review paper encompasses the inclusive approach of lime sludge valorization in construction materials. Research studies based on cement and aggregate replacement by lime sludge concludes that 10–30% lime sludge is gainfully utilized in sustainable concrete and mortar. Additional prospect for lime sludge application in construction material is the production of cement and ceramics. Significant use of lime sludge in combination with supplementary cementitious materials such as silica fume, nanosilica and fly ash is recommended for the production of cement components and ceramics. The recommendations are also suggested in accordance with the outcome of the study. [ABSTRACT FROM AUTHOR]

Abstract: Cotton waste results from the mechanical processing of raw cotton in yarn mills. Recycle Paper Mills constitute 30% of total pulp and paper mill segment in India. With 85% average efficiency of Recycle Paper Mills, 15% waste is produced annually. Recycle Paper Mills waste and cotton waste has been utilized to make Waste Crete Bricks. It helps in solid waste management, generate additional revenue and help in earning carbon credits. Waste Crete Bricks with varying content of cotton waste (1–5wt.%), Recycle Paper Mills waste (89–85wt.%) and fixed content of Portland cement (10wt.%) have been prepared and tested as per IS 3495 (Part 1–3): 1992 standards. The characteristics of raw materials, which is the base material for Waste Crete Bricks, have been determined using XRF, TG–DTA, and SEM. TG–DTA indicate that bricks is thermally stable up to a temperature of 280°C while SEM monographs show its porous and fibrous nature. The bricks meet of IS 3495 (Part 1–3): 1992. [Copyright &y& Elsevier]

• New material from cellulose and paper production process, concrete waste and lime production wastes. • Axial resistance reached 4.81 MPa in 3-day age samples, 8.75 MPa in 180 days, and 9.61 MPa in 365 days. • By methods of XRD, SEM and EDS were founded the processes of the materials hardening. • Utilization of industrial wastes has high environment and economic efficiency. The mechanical and physical properties of the composites developed from dregs, grits, and lime mud of the Kraft cellulose and paper production process (55–75%), concrete waste (10–25%) and lime production waste (0–25%), far exceeded the demands of Brazilian standards for bricks, blocks, and road-base construction materials. The study of the developed composites structure by XRF, XRD, SEM, EDS, and LAMMA methods demonstrated that new mainly amorphous formations were responsible for all attained properties. The industrial application of these construction materials would introduce excellent efficiency from an economic and environmental points of view. [ABSTRACT FROM AUTHOR]

• Reusability of PMS and CS provides economic and environmental benefits. • PMS and CS can be utilized as a pore making agent in sustainable brick manufacturing. • The energy efficiency problem of buildings can be solved using the produced lightweight and thermal insulated bricks. • ANOVA revealed that the characteristics of the fired bricks depends on the selected mixture ratio. In terms of sustainable and cleaner production, the utilization of various industrial wastes in the manufacturing of eco-friendly building materials has attracted attention in recent years. In the present study, a total of 12 series bricks were produced to determine the influences of paper mill sludge (PMS) and carbonation sludge (CS) on the physical, mechanical and thermal properties of clay based bricks. The following parameters were examined for the bricks produced at 1000 °C and 1100 °C; water absorption, apparent porosity, efflorescence, bulk density, compressive strength and thermal conductivity. For the fired brick production, CS was used up to 30% while PMS up to 15%. The compressive strength of the fired bricks having 15% CS and 5% PMS content were in accordance with the standards. The thermal conductivity ranged from 0.742 W/mK to 0.155 W/mK. Also, the influences of waste concentrations on the quadratic model were analyzed using analysis of variance (ANOVA). The analysis results indicate that the firing temperature is the least important parameter affecting all properties of brick. The use of wastes up to 20% in the brick structure is an important step both in terms of reducing environmental pollution and protecting natural clay resources. [ABSTRACT FROM AUTHOR]

• Paper and pulp residues are used for manufacturing adobe bricks. • Compressive strength is increased up to 190% for 12.5% of replacement. • Thermal conductivity is reduced approx. 30% for 12.5% of replacement. • The water resistance complies with standards up to 12.5% of replacement. • Toxicity values meets the standards up to 20% of replacement ratio. Soil-based building material has been used since ancient times but lately it has been mainly considered for restoration purposes of traditional architecture instead of an eco-friendly construction material for new buildings. However, the promotion of a more sustainable architecture has recently led to look towards adobe or rammed earth, among others. Because of the high impact of concrete and the fired clay brick industry, mainly due to the use of clinker and the firing process, respectively, adobe may highly reduce the ecological footprint of conventional construction and building materials. In addition, the use of fibers for adobe reinforcement has been also highlighted as a key factor for improving adobe performance. Obviously, when residues successfully replace such fibers the ecological footprint may be reduced even more. Thus, this research focuses on the assessment of adobe reinforced with paper and pulp industry residues (PPR) with the aim of demonstrating the feasibility of this construction material. Several series have been made by varying the replacement percentage up to 20% and technological properties and toxicity have been assessed. It is concluded that compressive strength may be improved up to 190% while thermal conductivity is reduced approx. 30% for 12.5% of PPR replacement. Besides, adobe meets standards related to water resistance and toxicity values. [ABSTRACT FROM AUTHOR]

• The utilization of paper sludge develops energy-saving CSBM with enhanced properties. • RSM is an effective method to predict the properties of sustainable CSBM. • Paper sludge benefits to the development of waste management and energy efficiency. Calcium silicate board materials (CSBM), as a new environmental friendly and energy-saving building material, have been widely used in the construction of ceiling and insulation panel. This study aims to investigate the feasible utilization of two kinds of paper sludge powder, paper sludge ash (PSA) and alkali recovery paper sludge (ARPS), as the supplementary materials to develop a sustainable CSBM with low water-cement ratio. The experimental results indicate that single addition of 30% PSA or 20% ARPS can improve the flexural strength of CSBM effectively because a moderate addition of paper sludge can decrease the porosity. Meanwhile, the addition of PSA or ARPS notably reduces the thermal conductivity of the CSBM and DSC-TG analysis present a better thermal stability before 650 °C. Furthermore, the reinforcing capability of the hybrid PSA/ARPS to CSBM is investigated using response surface methodology (RSM). In conclusion, the utilization of paper sludge powder presents a great potential to develop sustainable and energy-saving CSBM with enhanced flexural strength and reduced water absorption. [ABSTRACT FROM AUTHOR]

• The waste paper is transformed into Aggregates of Waste Paper (AWP). • New biocomposite based on the Aggregates of Waste Paper and Lime (AWPL) is formulated and characterized. • The microstructure of the new composite AWPL is characterized by high open porosity. • The thermal conductivity of the material AWPL are ranging between 0.097 and 0.012 W/mK. • The compressive strength of the material AWPL is ranging between 4.2 and 10.95 MPa. • The new material AWPL can be used as structural material and thermal insulation. In the aim of the valorisation of waste paper, an experimental study of a new biocomposite (AWPL) dedicated to building based on Aggregates of Waste Paper and Lime is performed. The waste paper used in this work is transformed to Aggregates of Waste Paper (AWP), the physical, thermal and morphological properties were carried out. Five combinations of (AWP – Lime) have been prepared and the weight ratios of lime used are 20, 30, 40, 50, and 60 wt% correspond. Experimental investigations of physical, mechanical, thermal and morphological characterizations of AWPL were carried out in order to determine: the apparent density, the open porosity, the water absorption, the ultrasound pulse velocity, the flexural and compressive strengths and the thermal conductivity. Furthermore, a characterization by Scanning Electron Microscopy (SEM) was realized to observe the AWP/lime bond. The results of characterization of AWPL show good mechanical properties as flexural and as compressive, these results are confirmed by the analysis SEM, that shown good adhesion of the AWP/Lime interface. The thermal characterization tests of AWPL have shown an important thermal insulation capacity linked to the low values of the thermal conductivity, these low values can be explained by the high porosity of AWPL. As a result, the AWPL could be classified as a structural and thermal insulation material for buildings according to the RILEM classification. [ABSTRACT FROM AUTHOR]

Abstract: This study was to develop a new building material, Wood-Crete, using sawdust, waste paper and Tradical lime. The paper presents the processing technologies, factors which affect the performance of the developed composites, and properties of Wood-Crete. The results showed that lightweight sustainable blocks can be produced with good insulating and other relevant properties for building construction with density ranging from 356 to 713kg/m3 and compressive strength from 0.06 to 0.80MPa. The properties were closely related to the composition of Wood-Crete with an addition of waste paper being a dominant influence on both strength and thermal conductivity, reflecting its effect on the structure of composite and contribution of self strength of paper fibres. The combined effect of sawdust and waste paper and Tradical lime had a direct effect on the strength properties of Wood-Crete. Of significant importance was the contribution of self strength of Wood-Crete due to the influence of the size of sawdust particles used. The developed Wood-Crete was able to withstand considerable amount of impact load and considered, like hempcrete, most suitable for wall panelling or other non- and semi-structural applications with good thermal insulating properties. [Copyright &y& Elsevier]

• The advantages of degradable resins in the recycling process of CFCs are highlighted. • The application of WCFs in cement-based materials, lithium-ion battery materials, and other functional fields is analyzed. • The possible problems of carbon fiber recycling methods are added, and future directions for improvement are proposed. Carbon fiber composites (CFCs) are widely used in modern industry with their excellent properties. However, a large amount of CFCs waste has been produced because of the limitations of the processing technology and service life. And in the next 20 years, the amount of waste will increase dramatically, resulting in environmental pollution and waste of resources. How to efficiently recycle and reuse CFCs is a common problem faced by mankind. Facing the shortages of traditional recycling technology, this paper focuses on the recycling of CFCs by various new degradable resins, including degradation conditions, degradation mechanism and degradation effect. Meanwhile, the application of waste carbon fibers (WCFs) in cement-based materials (Mechanical and electrical conductivity, etc.), lithium-ion battery materials, thermoelectric materials, and other functional fields (Fillers, electromagnetic shielding, and parts manufacturing, etc.) are described in detail. The recycling of WCFs is imperative, but the traditional resin is not easily degradable, which is the biggest obstacle to the recycling of WCFs. Degradable resin-based CFCs has huge application prospects in the future. With appropriate recycling techniques, the strength of WCFs will be lost by 5 % to 50 %, but it still meets the requirements for use in construction materials and some industrial fields. [ABSTRACT FROM AUTHOR]

• Calcareous sludge is used as filler in geopolymeric mortars. • Biomass fly ash is used as main alumina-silicate source (70 wt%). • Used wastes derive from a Kraft pulp industry. • Manufacture is simple and highly sustainable and reproducible. • Novel geopolymeric mortars are suitable for construction applications. Calcareous sludge is an alkaline waste produced by the paper pulp industry that is commonly disposed of in land-fill. However, recent studies and the European regulations discourage such practice. This work investigates an alternative and innovative way to recycle and reuse this waste, as filler, in the production of green geopolymeric mortars intended for applications in construction. This is the first time that this calcareous sludge is used to produce novel waste-based materials, in both construction and geopolymer technology. The novel alkali-activated mortar also uses biomass fly ash – another slightly investigated waste stream – to substitute the metakaolin (70 wt% substitution) and the manufacture process is performed at ambient conditions. All of that reduces the overall process footprint. The implemented mix design is aimed at maximising the waste incorporation and improving the material properties, such as workability and mechanical performance. The main results demonstrate that 10 wt% of calcareous sludge can be efficaciously used as filler in the geopolymeric mortars, generating up to 30% improvement in the mechanical resistance. This alternative use of such wastes will contribute to increase the sustainability of the novel construction materials also granting environmental advantages and a financial surplus for the industry. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

• The comment concerns a paper published in Construction and Building Materials. • The Mittag-Leffler function is used in the paper. • The Mittag-Leffler function is defined only with dimensionless parameters. • In the paper, in the Mittag-Leffler function dimensional parameters have been used. [ABSTRACT FROM AUTHOR]

Abstract: Due to the growing extent of the sources of aggressive media, the concrete structures may be exposed to the action of organic species. The paper presents the results of the long-term study on the action of various organic substances on the cement-based material. The results obtained show the different aggressivity of the solutions of phenols, carboxylic acids and sulphonic compounds. Petroleum and mineral oil have been shown as unaggressive media. Observed increased expansions followed by crack propagation at the action of some media were adjudged to the cooperation of the mechanism of acidic attack and dispersive effect of surface activity of organic substances. [Copyright &y& Elsevier]

Abstract: Two modifications have been proposed for the Nurse-Saul maturity function to get better estimates of compressive strength of concrete cured at different temperatures in this paper. The modifications account for the effect of w/c ratio on the temperature dependence of strength development and the effect of curing temperature on the long-term strength. This discussion focuses on strength development behaviour of concretes cured at different temperatures. Aiming to understand the strength development of cement based materials relevant experimental studies on mortar and concrete specimens in the literature are evaluated. [Copyright &y& Elsevier]

Transparent bamboo (TB) stands as a promising biomass composite material, offering a range of merits including a straightforward preparation, high light transmittance, environmental sustainability, superior mechanical properties, and low thermal conductivity. These characteristics position TB for versatile application spanning energy-efficient building materials, decorative elements, and optoelectronic devices. This comprehensive review aims to elucidate the optical synthesis mechanism of TBs, delving into their functionalization improvement and exploring the potential applications across various domains. This paper serves to furnish readers with a profound understanding of the evolving landscape of TBs and their potential transformative impact. • This paper reviews the synthesis mechanism, preparation process, functional improvement of Transparent bamboo (TB). • The structure, properties and functional characteristics of TB are discussed. • The potential applications of TB in building materials, interior decoration and optoelectronic devices are summarized. • The prospects and challenges for the development of TB are discussed. [ABSTRACT FROM AUTHOR]

Since 3D printed concrete has a promising application in engineering, the combination of 3D printing concrete and other building materials has become a hot research topic.This paper investigates the shear properties of 3DPM-NM specimens which use 3D printed mortar (3DPM) as the precast part and normal mortar(NM) as the cast-in-place part. Four different types of interfacial locking design were analyzed in this paper, including L-shaped, C-shaped, S-shaped and K-shaped. The shear damage law of the specimens was analyzed using digital image correlation (DIC) technology. The results show that L-shaped specimens are basically damaged along the shear surface during the loading process. Most of the initial cracks in the C-shaped, S-shaped and K-shaped specimens appeared along the interfacial bonding surface during the loading process. Then, the cracks in the C, S and K-shaped specimens continued to develop along the interfacial bonding surface or spilt through the specimens directly. The results show the shear properties of the C-shaped specimens are similar to those of L-shaped specimens. And the mechanical properties of S-shaped and K-shaped specimens are better than those of L-shaped specimens which increased by 96% (S-shaped), 78% (K-shaped) respectively. The mean slip is increased by 10% in S-shaped specimens and 28% in K-shaped specimens compared with that of L-shaped specimens. According to the AASHTO GSCB INTERIM-2003 specification, the modified formula for the shear bearing capacity of 3DPM-NM specimens is proposed in this study. The calculated resultsare in good agreement with the test results, which theoretically provide guidance for the application of 3DPM, lay the foundation for its feasibility as a structural body of a building. • Specimens with 3D printed mortar (3DPM) as a precast component and normal mortar(NM) as a cast-in-place part were tested. • Comparison of the shear performance of specimens with different types of interfacial locking design were conducted. • Theoretical analysis and modified calculations of shear strength for 3DPM-NM interfacial locking specimens were carried out. [ABSTRACT FROM AUTHOR]

In this paper an overview is presented on the use of diatomaceous earth (DE) as a partial substitute for binder and fine aggregate in mortars. For this purpose, this paper was divided into two sections. In the first one, concepts related to physical, chemical and microstructural properties of DE, as well as results of previous studies about its reactivity used in different construction materials (cement, concrete, mortar, bricks, phase change materials etc.) were summarized and discussed. In the next section, the effects of using DE on the fresh, hardening and durability properties of cement and lime-based mortars were discussed. In general, the results suggest that increasing DE content may reduce mortar performance due to the high porosity of its particles. However, this deficiency was observed for DE contents higher than 20%, which, however, can be compensated for by using superplasticizer additives or by volumetric dosage instead of by weight one. This critical value of up to 20% of DE was calculated using T2 statistical on the scores of principal components analysis obtained from the results collected from publish manuscripts. Nevertheless, the results of this review research may contribute to provide information on an under-explored alternative source of supplementary cementitious materials (SCMs) and therefore help mitigate the negative effects generated by the cement industry and assist in the production of mortars with a lower carbon footprint that can play an important role in the thermal behavior of buildings. • State of the art systematic review of diatomaceous earth (DE) for mortar production. • Statistical analysis of the mechanical properties of mortar with DE. • Understanding the effects of DE on properties of mortars. • When up to 20% DE is used, the mechanical behavior of mortars can be improved. • Paths for the development of new studies on mortars incorporating DE are shown. [ABSTRACT FROM AUTHOR]

Capillarity has an important effect on the durability of buildings, and the capillary absorption coefficient is a key parameter to describe the strength of material capillarity. Most of the methods currently used to measure the capillary absorption coefficient of materials can damage the sample or are not accurate enough and need to be improved. This paper proposes a method to measure the capillary absorption coefficient of brick, sandstone, mortar and concrete by using a single-sided nuclear magnetic resonance (NMR) technique, which has the advantages of accuracy, nondestructiveness, continuity and rapidity. The relative error of the capillary absorption coefficient obtained from three repetitions of the experiment ranges from 0 to 5.11%, which is in the range of 0.64%∼1.30% compared with that obtained by the partial impregnation method. This method has great potential for application in in situ testing. This paper also analyzed the water transport behaviors in porous building materials based on the variation in NMR signal intensity in the measured materials and established a water transport model. The model is divided into two stages: the first stage is mainly the one-dimensional rise in moisture in the vertical direction. The second stage is mainly the diffusion of moisture in the horizontal direction, which continuously fills each pore space to saturation. Difficulty in removing air leads to a reduced rate of water absorption in the second stage. • A method is presented for measuring capillary absorption coefficients of porous building materials using single-sided NMR. • The water absorption behavior of porous building materials was analyzed. • A water absorption model is proposed for porous building materials. • The feasibility of conducting in situ measurements using single-sided NMR is discussed. [ABSTRACT FROM AUTHOR]

The disposal of steel slag in landfills not only squanders precious landfill resources but also results in significant environmental contamination. Steel slag can be used to replace cement and natural aggregates in concrete. Nonetheless, utilizing untreated steel slag directly presents a substantial hazard to the structural characteristics and durability of concrete. To avoid this problem, study on accelerated carbonation of steel slag as construction materials has been extensively conducted. This review paper begins by introducing the classification and physicochemical properties of steel slag; it then describes the typical approaches of steel slag carbonation, including direct carbonation (dry carbonation, wet carbonation) and indirect carbonation (pH-swing, microbial carbonation), along with their processes and carbonation mechanisms. Furthermore, based on the reviewed literature, the influences of various reaction parameters such as reaction time, liquid-to-solid ratio, temperature, additives, CO 2 concentration, pressure, pH on carbonation effectiveness are analyzed. Also, the impact of carbonated steel slag on the micro-pore structure, stability, workability, and mechanical properties of concrete is discussed. Finally, the challenges and future work of using carbonated steel slag as construction materials are provided. • The current papers on steel slag classification, physicochemical properties, and methods for accelerated carbonation are reviewed. • The traditional carbonation methods, as well as recently proposed microbial carbonation methods are analyzed. • The factors influencing the efficiency of steel slag carbonation are summarized. • The impact of carbonated steel slag on concrete properties are concluded. • Insights into accelerated carbonation methods for steel slag and future work are provided. [ABSTRACT FROM AUTHOR]

Blast furnace slag (BFS) is commonly used as a substitute for cement clinker due to its hydration properties. However, the demand for BFS is outpacing the supply, and its price is rising steadily. Moreover, the significant accumulation of industrial waste with potential hydration properties poses a severe environmental threat. To address these challenges, this paper aimed to prepare high-performance composite blast furnace slag powder (CBFS) by incorporating red mud (RM), fly ash (FA), desulfurization gypsum (DG) and BFS, guided by the synergistic effects and the theory of medium-calcium systems. This paper reveals that the primary activation methods of the amorphous silicon-aluminum mineral phases in CBFS are alkali activation and sulfate activation. The optimal results demonstrate that the compressive strength of CBFS-cementitious material (50% CBFS + 50% cement) can reach 52.8 MPa, meeting the standards of Portland Cement PO 42.5. Additionally, RM, FA and DG account for 66% of CBFS and the hydration activity of CBFS is better than that of S95-grade BFS. Furthermore, the CBFS-cementitious material effectively immobilizes hazardous elements of the raw materials, and the leachate meets drinking water standards. The application of CBFS facilitates the recycling of industrial solid wastes, improves the quality of construction materials and reduces the construction industry's dependence on BFS. [Display omitted] • CBFS was prepared using RM, FA, DG, and BFS, aiming to achieve integrated clean production in multiple industries. • The total content of RM, FA and DG in CBFS reaches 66%, and its properties meet the requirements of S95-grade BFS. • RM, FA, DG and BFS showed a positive synergistic effect in CBFS, which enhanced the strength of the matrix (52.8 MPa). • CBFS can reduce carbon emissions in the cement industry and solidify the hazardous elements in the raw materials. [ABSTRACT FROM AUTHOR]

• Introduction of new type of wood building material based on glulam from spruce and veneers from beech. • Inherently reinforced wood product with high capacity for load redistribution. • Proof of significantly improved properties perpendicular to the grain and in shear. • Multiplied load-carrying capacities at details such as notches, holes and cross-connections. • Homogenization of multiple glued veneer layers leads to mean tensile strengths > 100 MPa. This paper deals with the development of a novel veneer-reinforced timber product for load-bearing applications – veneer-reinforced timber. For this composite timber product, veneers are inserted vertically into a glulam cross-section to act as reinforcement for shear and tension stresses perpendicular to the grain. By arranging the veneer layers between the glulam components at angles of 0°, 45° and 90°, the highly anisotropic strength and stiffness properties of glulam are homogenized. By means of numerical simulations and experimental investigations, the load-bearing behavior and the efficiency of veneer-reinforced timber are investigated. The results substantiate a considerable increase in load bearing capacities of veneer-reinforced timber with notches, holes or cross connections. Studies and derived recommendations on the effect of the inclination of the veneer on the shrinkage behavior of this composite timber product conclude this paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • The properties of red mud used for filling resin composites are reviewed in the field of building materials. • The environmental hazards of red mud are described. • The processing methods and principles used to research red mud as a filler for resin composites are compared. • The technical difficulties in the research and application of red mud in resin composites are described. • Methods and suggestions for using red mud to enhance the properties of resin composites are provided. Red mud is a harmful alkaline waste discharged during alumina production, and the environmental pollution caused by red mud accumulation has become an increasingly serious problem. Incorporating red mud into resin composites can improve the properties of the composites because of its special structure and composition. It can also reduce the use of non-renewable resources required for resin production, such as petroleum, thereby reducing carbon emissions and production costs. Incorporating red mud into resin composites is expected to protect the environment from the harm caused by red mud while achieving sustainable economic and environmental development. This paper mainly provides a comprehensive review of the research status of red mud used to fill and modify resin composites in the field of building materials. Different treatment methods for red mud fillers and different composite preparation processes are used to improve the properties of composites, which are discussed in detail. The theory of the formation and bonding of the interface between red mud filler and resin is described. The importance of this paper is in summarising the technical difficulties incorporating red mud into resin composites and providing suggestions and prospects for future research. [ABSTRACT FROM AUTHOR]

• Analysis of the impact of recycled wastewater on the physical, chemical, and mechanical aspects of concrete. • Comprehensive assessment of recycled wastewater influence on concrete durability, microstructure, and strength properties. • Examination and elucidation of interrelationships among diverse properties of environmentally friendly concrete. • Future research insights and recommendations to drive innovation in sustainable concrete practices. The present paper endeavors to examine the viability of utilizing recycled wastewater as a foundational component in the creation of eco-friendly concrete. This paper entails an in-depth analysis of the chemical and physical attributes inherent in recycled wastewater, with a particular focus on its potential as a substitute for conventional freshwater in the concrete mixing process. To address limitations observed in prior research and to achieve a more profound comprehension of recycled wastewater's performance within green concrete, this study conducts an exhaustive review of existing literature. Through a systematic evaluation, the study meticulously assesses the influence of recycled wastewater on diverse properties inherent to green concrete, encompassing pivotal factors like flexural and compressive strength, alongside durability properties. The outcomes drawn from this investigation accentuate the viability and efficacy of recycled wastewater as a feasible alternative to freshwater in the production of green concrete. Notably, this approach holds promise for ameliorating detrimental environmental impacts while concurrently reducing the cost burden associated with sustainable concrete fabrication. Nevertheless, a central message emerges concerning the necessity for vigilant monitoring and meticulous regulation of recycled wastewater's quality and composition. This requisite vigilance is aimed at ensuring its compatibility and appropriateness for integration into concrete formulations. By virtue of delivering a comprehensive and thorough analysis of recycled wastewater's effects on the production of green concrete, this study plays a pivotal role in bridging gaps in knowledge and advancing the boundaries of this field. The practical implications of these findings extend to the development of sustainable and ecologically mindful concrete structures, while also serving as a guiding light for future research endeavors in this pivotal domain. [ABSTRACT FROM AUTHOR]

[Display omitted] • This is a state-of-art review of rubberized recycled aggregate concrete (RRAC) and fiber-reinforced rubberized recycled aggregate concrete (FRRAC). • Different mechanical properties, microstructural analysis, and life cycle assessment of RRAC and FRRAC have been reviewed. • Extensive regression analysis has been conducted to predict different mechanical properties of RRAC and FRRAC. • Crumb rubber (CR) and recycled coarse aggregate (RCA) reduced the strength, however, fiber addition could have a positive response. • Addition of CR and fibers enhanced the toughness and ductility of RRAC; however, excessive amount of CR negatively affected the toughness. • RCA and CR can be used up to 30% and 10%, respectively. The growing population demands rapid development of infrastructures. However, the construction industry is searching for environmentally sustainable and eco-friendly building materials to fight climate change. Millions of tires are discarded globally, and only certain percentages are recycled. The use of rubber tires as a natural aggregate replacement in concrete has gained popularity among the research community in the past few years, primarily due to its ductility and toughness properties. A significant number of investigations have been reported in the past using recycled coarse aggregates (RCA), crumb rubber (CR), and fibers separately in concrete. The results revealed that the addition of rubber particles along with RCA in concrete reduced the strength. However, the inclusion of fibers in the same mixtures significantly improved the mechanical properties of concrete by acting as a bridge within the concrete matrix for the surrounding cracks. In this review paper, over 220 research articles from the last 30 years reporting the effect of RCA, CR, and fibers on the mechanical and physical properties of rubberized recycled aggregate concrete (RRAC) and fiber-reinforced rubberized recycled aggregate concrete (FRRAC) are summarized. This paper presents in detail the influencing factors that affect the physical and mechanical properties of RRAC and FRRAC. The performance of FRRAC depends on the types of fiber and CR, treatment of CR, RCA sources, and the mix design of concrete. Based on the review, recommendations are provided for optimized FRRAC production. Simplified equations have been proposed to predict the tensile and flexural strength and modulus of elasticity of RRAC and FRRAC. An overview of predicting the mechanical properties of rubberized concrete using different machine-learning algorithms has been presented. Finally, this review paper will help scholars understand the use of RCA and CR in concrete as aggregate replacement materials and create waste material utilization opportunities for the sustainable green construction industry. [ABSTRACT FROM AUTHOR]

The adoption of natural construction materials can help mitigate the environmental impact of the construction industry by reducing the amount of energy required and emissions. Among the natural materials, bamboo is a remarkable option, combining high mechanical resistance with a low specific weight and a very high growth speed; however, its application is limited by the absence of a suitable grading method. This paper aims at filling this lack by providing a strength-based grading methodology relying on a four-point bending test. Experimental results were processed considering bamboo both as a homogeneous material and as a non-homogeneous material and using the ANOVA test. Results show that statistical groups can be defined which are not based on the bamboo species, but on the values of the mechanical properties, hence supporting the appropriateness of strength classes. The bending tests used in this paper could be a crucial test for bamboo grading: it is easier to perform than a tensile test and it gives complete information on the change of material properties along the culm wall thickness. The study focuses on six different species of bamboo grown in Italy, for which little data is present in the literature. • Four-point bending test could be a crucial test for bamboo grading. • The flexural properties of six species of bamboo grown in Italy are discussed. • A strength-based grading methodology based on a four-point bending test is provided. • A classification scheme can be defined based on the mechanical properties of bamboo. [ABSTRACT FROM AUTHOR]

• Structural relationship model between maintainable building material selection criteria and building maintainability. • Criteria of TPM, DD, MPM, CPM, ME and SB are the most significant ones for optimising building maintainability. • It is advocated that these sets of criteria need to be used in selecting materials for achieving building maintainability. The purpose of this paper is to investigate the principles and criteria that govern selection of building materials in achieving building maintainability. The methodological approach used findings generated from extant literature to establish a set of principles and respective criteria for selecting building materials in respect of their influence in achieving building maintainability in post construction (occupancy) period. Further, a modified Delphi method, comprised of a series of questionnaire surveys among the sample of experts drawn from relevant fields including architecture, maintenance, structural engineering and so on, was conducted and the data obtained from which were used to reveal the relationships between the criteria and building maintainability. This paper presents findings on material selection criteria and their relationship to building maintainability. A structural relationship model showing the relationship between maintainable building material selection criteria - attributed to respective principles - and building maintainability is presented. Principles like "Technical Performance of Materials", "Documentation and Details", "Mechanical Properties of Materials", "Chemical Properties of Materials", "Material Economy" and "Social Benefit" have been identified as the most significant ones for optimising building maintainability in general. It is advocated that these sets of criteria attributed to respective principles need to be formally used in selecting materials for achieving building maintainability. This research is context-bound exclusively to the Malaysian construction industry. Its wider implications need further investigations. This study contributes to the building industry and maintainability research in at least one significant aspect that it widens understanding on maintainability criteria to be considered in selecting maintenance friendly materials and their influence in partially achieving post construction maintainability. The model presented in this paper would enable decision makers to ascertain, during the design phase, what maintainability principles and criteria would require more attention than others to achieve building maintainability. [ABSTRACT FROM AUTHOR]

• Experimental study identifying the limit states of rammed earth walls. • Four RE walls were tested under bi-axial loading. • Cracking evolution recorded by the digital image correlation technique. • Four limit states proposed for RE walls based on the damage evolution. Rammed earth (RE) is a construction material manufactured from the soil. This material attracts the attention of numerous scientific investigations during the past decade due to its sustainable properties. The performance of RE buildings under horizontal loadings remains an important topic to be investigated. This paper presents an experimental study which identifies the limit states for the in-plane seismic assessment of RE walls. Four RE walls were tested under bi-axial loading: first a vertical force was applied on the top of the wall to simulate the dead and live loads in a building; then a horizontal force pushed at the top the walls to simulate a seismic action. The cracking evolution was recorded by using the DIC (digital image correlation) technique in which the displacement fields were determined by comparing the images taken after and before the loading. Based on the damage evolution observed during the tests and on a similar approach of unreinforced masonries, the present paper proposed four limit states for RE walls corresponding to the inter-storey drift δ: no damage (before LS1) and slight damages (before LS2): δ < 0.1%; moderate damages (before LS3): 0.1% ≤ δ < 0.3%; extensive damage (before LS4): 0.3% ≤ δ < 0.6%; compete damage or collapse (after LS4): δ ≥ 0.6%. This is the first time these limit states are proposed for RE walls. [ABSTRACT FROM AUTHOR]

• Multivariate optimisation and statistical analyses were conducted on scaffold boards. • Effects of the selected wood defects on the performance of boards were investigated. • 0.3 TKAR and 0.1–0.17 MKAR were determined as the most critical values. • Failure is independent from knot defects for the low density and growth rate boards. The uncertainties involved in the prediction of scaffold material performance in the machine grading process have brought forth the necessity to identify the level of influence of wood defects on the scaffold performance required to be optimised for its intended use as a construction material. This paper tackled this important aspect by employing multivariate optimisation and statistical analyses on the previously reported experimental results in the literature on the machine graded scaffold boards from UK Sitka spruce (picea sitchensis) softwoods. Initially, nonlinear multivariate regression analyses were performed for the responses of such variables as failure load, displacement, extreme fibre stress and the critical failure distance to several wood characteristics as contributing factors. The extension of the statistical analysis to the multi-objective optimisation study was accomplished using Response Surface Method (RSM) by considering the mutual interactions between the factors including total and margin knot area ratios, density, rate of growth and slope of grain. This paper represented graphically how the load bearing capacity, the deformation characteristics and the critical failure location points are influenced by the considered factors. The significance of factors and their relative influence on the performance optimisation were finally discussed by providing the essential information on the future use of scaffold board products as construction material. [ABSTRACT FROM AUTHOR]

• Permeability and pore structure of the porous concrete mix was checked with over burnt brick aggregate. • A nonlinear relationship was obtained between permeability and porosity of porous mix. • Minimum permeability for single sized and dense graded aggregate was found to be 0.5 cm/s and 1.4 cm/s, respectively. • An increase in aggregate size leads to the increase in permeability. • Kozney-Carman model for permeability is modified for over burnt brick aggregate. The scarcity of regular construction material has always been a challenging concern in some of the North-Eastern states of India like Tripura. To meet this inordinate shortage, brick aggregate has earned an immense attention due to its availability and low cost. The main purpose of this paper is to correlate the pore structure and hydraulic conductivity of the porous concrete matrix using brick aggregate to meet the insufficiency of conventional aggregates. Pervious concrete pavement, due to its eminence as an eco-friendly pavement system, has become an emerging technology in the developed and developing countries. In this paper, a series of pervious concrete mixes are made with over burnt brick aggregate and the porosity and permeability are evaluated. Water-cement ratio, aggregate size and the presence of fine aggregate in the porous mix are chosen as the mix variables and their contributions in controlling the permeability is quantified. A relationship is then drawn between permeability and the pore features considering the relative mean pore size and pore tortuosity. A modified Kozney-Carman model for pervious concrete is also developed using the investigational test results and the predicted equations. The predicted values and the developed relationships provide a very good agreement with experimental test results. [ABSTRACT FROM AUTHOR]

• The engineering characteristics of typical earthen site soil are tested. • Variable factor compaction tests are carried out to study the compression mechanism of earthen site soil. • The influence of drop distance is great but decreases with the increase of compaction energy. • Medium hammer weight easily obtains large dry density; excessive falling distance should be avoided. • A parameter λ is introduced to evaluate the effect of compaction factors on maximum dry density. Soil, as an important building material, has been widely used for a long time. Earthen sites are representative ancient buildings made of rammed soil. As significant archives of human history, culture, and architecture, earthen sites are seriously deteriorated by age, poor conservation, and exposure to the environment. Therefore, the restoration and protection of earthen sites are necessary and urgent. Northwest China has a long history and the earthen sites in this area are widely distributed, numerous and highly valuable. In order to understand the characteristics of the earthen site, a typical site in this area is taken as a case to test the physical, mechanical, and environmental durability of the site soil. The site soil is silt; it is low in the liquid limit and plastic limit, the particle size distribution is good, the material is uniform and compact, the density and strength are extremely high, and the environmental durability is excellent. In view of the problems existing in the earthen site restoration, such as over-reliance on chemical methods, risk of causing new damage and poor similarity after restoration, this paper proposes that the earthen sites should be restored with the material and technology which are similar to the original site. In order to make the restoration material as close to the original site as possible, the soil near the site is selected and particle size distribution is optimized. By changing the variable factors in compaction test, namely hammer weight, hammer blow number, and the drop distance, the compaction mechanism of the site soil is tested; the influence of different compaction factors on maximum dry density is revealed; and a compaction influence parameter λ is introduced to evaluate the influence of compaction factors on the maximum dry density. Contrast test shows that by selecting similar materials and techniques, the maximum dry density and other engineering properties obtained from the compaction test are close to the original site soil. The comprehensive performance of the compacted sample is much better than lime soil which is usually used to restore earthen sites. This result shows that it is feasible to select nearby materials and original techniques so as to make restoration site more similar to original site. The findings in this paper can provide reference for better restoration of earthen sites. [ABSTRACT FROM AUTHOR]

• Thermal diffusivity measurement of hemplime concrete. • Thermal testing of approx. 1 m by 1 m wall panels. • Direct measurement of conductivity, diffusivity and heat capacity from a single test. • A diffusivity of 1.56 × 10−7 m2 s−1 was measured. • A conductivity of 0.129 0.7 W m−1 K−1 was measured. Hemplime concrete is a material that has a different combination of properties to other, more traditional, building materials, and as such it exhibits potential advantages. Its thermal mass characteristics are often viewed as favourable to reducing the energy used to heat or cool indoor buildings. As a dynamic property, the effects of thermal mass on thermal behaviour depend not only on the conductivity but also on the heat capacity of the materials; the combination of conductivity and heat capacity being the diffusivity. The thermal diffusivity of hemplime concrete is comparatively under-researched, particularly given that most measurement techniques are designed for small samples of homogeneous material and may not give accurate results for inhomogeneous, anisotropic materials such as hemplime. This paper uses a technique recently developed for testing the diffusivity of whole wall panels, to measure the diffusivity of a section of hemplime wall, establishing the diffusivity as 1.56 × 10 - 7 ± 3.8 × 10 - 8 m2 s−1. This method may offer more accurate results. This paper compares the results of diffusivity measurements using this new technique, to diffusivity values calculated through measurements of the thermal conductivity and heat capacity via separate tests. The new technique is found to give results in agreement with previous techniques. The property space filled by hemplime is contrasted with timber, hard aggregate concretes, and insulating materials. [ABSTRACT FROM AUTHOR]

• Waste generation is a major concern worldwide due to its environmental, economic, and health impacts. • Microbially Induced Calcite Precipitation (MICP) is a sustainable technology that can transform waste into valuable applications. • Waste streams can replace several MICP-chemical components, making it a cost-effective and sustainable solution. • The comprehensive review paper provides guidance for researchers to overcome challenges in applying MICP technology using waste streams. Waste generation is a growing concern in many countries across the world, particularly in urban areas with high rates of population growth and industrialization. The increasing amount of waste generated from human activities has led to environmental, economic, and health issues. Improper disposal of waste can result in air and water pollution, land degradation, and the spread of diseases. Waste generation also consumes large amounts of natural resources and energy, leading to the depletion of valuable resources and contributing to greenhouse gas emissions. To address these concerns, there is a need for sustainable waste management practices that reduce waste generation and promote resource recovery and recycling. Amongst these, developing innovative technologies such as Microbially Induced Calcite Precipitation (MICP) in construction materials is an effective approach to transforming waste into valuable and sustainable applications. MICP is an environmentally friendly microbial-chemical technology that applies microorganisms and chemical reagents to biological processes to produce carbonate mineral. This substance can be an energy-efficient, cost-effective, sustainable solution to environmental and engineering challenges. Recent research has shown that waste streams can replace several MICP-chemical components in the cultivation media of microorganisms and cementation reagents (calcium sources and urea). In addition to its effectiveness in treating hazardous waste streams, MICP has been found to be cost-effective and sustainable solution applicable to various waste media. This comprehensive review paper aims to provide a thorough understanding of the environmental advantages and engineering applications of MICP technology, with a focus on the contribution of waste streams. It also provides researchers with guidance on how to identify and overcome the challenges that may arise applying the MICP technology using waste streams. [ABSTRACT FROM AUTHOR]

The incorporation of Graphene Oxide (GO) nanomaterial into concrete has gained significant attention due to its potential to enhance mechanical and durability properties. The addition of GO to concrete creates considerable changes in the morphology of the concrete matrix, creating a densified microstructure. Critical parameters significantly affect these microstructural enhancements and, consequently, the final performance in GO-added concrete. These parameters include GO material properties, superplasticiser (PS) type, and dispersion techniques. Therefore, this study investigates the influence of GO on the mechanical performance of concrete, focusing on these critical factors. Unlike existing studies concentrating on a single parameter's effect, this research comprehensively compares how these parameters impact GO-added concrete. Two commercially available GO types (GO-A and GO-B) and two PS types (PS-A and PS-B) are utilised. At the same time, three commonly used mixing techniques, such as mechanical, high-speed, and ultrasonic mixing techniques, are considered for GO dispersion. GO-A is added to concrete in percentages ranging from 0.02 % to 0.14 % by weight of cement (bwoc), while GO-B ranges from 0.04 % to 0.20 % bwoc. Based on compressive strength test results, the optimum GO dosages are 0.08 % for GO-A and 0.12 % for GO-B. The highest strength results are achieved for GO-B added concrete with PS-A addition and following the ultrasonic dispersion method, highlighting these parameters as optimal for maximising GO-added concrete performance. The optimum concrete mix exhibits 33 %, 24 %, 25 %, and 30 % increments for compressive strength, indirect tensile strength, flexural strength, and elastic modulus properties at 28 days. This paper provides a deep theoretical explanation of the effects of GO material properties, dispersion techniques, and PS type on GO-added concrete performance. The findings provide valuable insights into selecting suitable parameters for optimising the mechanical properties of GO-added concrete, contributing to the advancement and effectiveness of construction materials. • Addition of Graphene Oxide (GO) is effectively improved the mechanical properties of concrete. • Choosing right GO, superplasticiser, & dispersion method is vital for optimal mechanical properties in GO-concrete. • Performance of GO-added concrete is greatly influenced by its dispersion level. • GO-added concrete dispersibility accomplished via ultrasonic dispersion polycarboxylate-ether-based superplasticisers. [ABSTRACT FROM AUTHOR]

In this paper, for the first time, we investigate the inherent ionic conductivity of seawater-based cementitious composites containing marine sand aggregates, when air cured over 28 days with the objective of uncovering new functionalities. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and density functional theory (DFT) were employed to elucidate the ionic conduction mechanisms in this material system and characterize its stress self-sensing and electrochemical charge retention capabilities. The results revealed that the marine aggregates are not ionic conductive materials; however, they facilitate improved electrochemical response through enhanced formation of highly ion-exchanging calcium-silicate-hydrate (C-S-H) phases, coupled with integrated porous channels that enable sustained ion mobility despite drying. This synergistic ion transport yielded a bulk ionic resistivity around 25 kΩ⊡cm at room temperature, which lies in typical ranges seen in solid-state electrolytes for battery systems. Controlled compressive loading indicates appreciable self-sensing capacity at low-stress levels, suggesting applicability to detect the onset of mechanical damage. Negligible charge leakage upon 28 days of curing further demonstrates the electrical energy storage potential of the sea-based cement. By harnessing locally available seawater and marine sand resources to develop ionic conductive cementitious composites, this work provides the framework to optimize durable multifunctionality for sensing and electrical energy storage in reinforced concrete infrastructure. This in return improves the sustainability and energy efficiency of the built environment. • A new approach to induce self-sensing and energy storage in cementitious composites using marine sand. • Marine sand enhances ionic conductivity, electroactivity, charge storage capacity, and self-sensing composites. • Coupling between self-monitoring and energy storage enables multifunctional structural materials. • Marine sand valorizes this abundant waste for advanced cement composites. [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]

Ammonium carbonate was used as the carbonation accelerator for air-hardening lime mortars in this study. Various analytical methods, including XRD, IR, TGA-DSC and SEM were employed to access the phase transformation, degree of carbonation and microstructural features of the lime-based mortars. The paper explores the correlation between the mechanical strength, microstructure of cured lime mortars and the composition/carbonation degree with the crystallization behaviors in Ca(OH)2/CaCO3 binders. The results indicate that ammonium carbonate significantly accelerates the carbonation reaction and increases the early mechanical strength of air-hardening lime mortars. The mechanical strength of these modified lime mortars can be comparable to that of natural hydraulic lime (NHL). The aggregation behaviors of nano-CaCO3 under kinetic control, are believed to contribute much to the compact pore-structures and robust mechanical strength of lime mortars. This viable accelerating carbonation method holds promise for enhancing the properties of various lime-containing building materials in conservation and modern buildings. • Ammonium carbonate is effective in accelerating the carbonation of aerial lime. • Lime mortars modified by ammonium carbonate rival natural hydraulic lime (NHL). • The mechanical strength is highly related to carbonation degree and pore structure. • Nano-CaCO 3 play pivotal role in compacting the pore structure of lime mortar. [ABSTRACT FROM AUTHOR]

Lightweight engineering geopolymer composites (LW-EGC) can contribute to green building materials products by taking advantage of the advantages of man-made ceramsite and geopolymers. In this paper, an active "sacrifice" method was proposed, which is based on the idea that low elastic modulus ceramsites are preferentially damaged or ruptured during the impact loading process, thus absorbing and dissipating the impact energy. LW-EGC was enhanced by PVA fiber with volume fraction of 2% and multi-walled carbon nanotubes with mass fraction of 0.15%. The dynamic compression properties of LW-EGC containing different ceramsites were studied by using Φ100 mm split Hopkinson pressure bar (SHPB) test device. The compression characteristics of the LW-EGC under an impact load were evaluated, including the strain rate, dynamic stress–strain relationship, elastic modulus, dynamic increase factor (DIF), energy absorption, and failure patterns. The results showed that the dynamic peak stress, dynamic peak strain, DIF, energy absorption and damage degree of LW-EGC all increased with the increase of strain rate, showing obvious strain-rate sensitivity. At high strain rate, the dynamic elastic modulus mainly showed softening effect. At the same strain rate, the impact resistance of LW-EGC-1 containing fly ash ceramsite was the best, and the damage degree of LW-EGC-3 containing shale ceramsite was the lowest. Empirical DIF formulas of the LW-EGC was proposed; the DIF increased approximately linearly with the strain rate in a logarithmic manner. • Effects of strain rates and ceramsite types on the dynamic properties of LW-EGC were studied. • The strain rate on the compressive properties ranges from 87.14 s−1 to 249.93 s−1. • Compressive properties of LW-EGC were sensitive to loading rates. • A DIF prediction model suitable for LW-EGC was proposed. • Energy absorption capacity of LW-EGC was studied. [ABSTRACT FROM AUTHOR]

Residential construction materials have undergone a notable evolution within the construction sector. This paper extensively reviews various types of bricks and building materials commonly employed in house construction, categorizing them into classifications such as typical clay, concrete, fly ash, and new materials such as aerated concrete and recycled bricks. The study thoroughly investigates the mechanical, thermal, and environmental potentials of each material, also considering auxiliary building materials like mortar, cement, and bio-materials, which play vital roles in house construction. Its primary objective is to offer valuable insights to architects, engineers, builders, and researchers to facilitate informed decision-making in residential construction projects. It also considers factors such as sustainability and local availability. The research identifies Cellular Lightweight Concrete (CLC) bricks as the optimal choice for residential construction, given their compressive strength of up to 30–40% more than traditional bricks, along with excellent lateral load capacity and displacement ductility, also making them suitable for constructing partition walls. Modifications in composition, such as incorporating coconut and basalt fibres, result in a notable enhancement of approximately 17.4% in thermal insulation with minimal impact on thermal degradation. Ultimately, this review serves as a valuable reference for individuals seeking a deeper understanding of the diverse options available in bricks and building materials for modern residential construction. • Various bricks and building materials for residential construction are reviewed. • Investigate the mechanical, thermal and environmental potential of each material. • Alternative materials like fly ash, mycelium, geopolymer, LTC, and 3D-printed bricks were explored. • Insights into the potential of diverse bricks for sustainable and eco-friendly building practices. • Critically highlight research gaps and provide directions for future studies. [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]

Salt weathering is one of the most threatening issues for the preservation of our built cultural heritage comprised of porous materials. After salt accumulation in the pores, cyclic crystallization and dissolution processes can lead to material damage when the crystallization pressure, which is directly influenced by the supersaturation of the pore solution, acts on the material. Following the presentation of the damage potential and achievable supersaturation of potassium nitrate in a previous paper, this study reports results for the nitrates of sodium, magnesium and calcium for the first time. Two different types of damage tests with impregnated sandstone specimens were performed to assess their actual damage potential, also including the well investigated sodium chloride for comparison. Significant deterioration was revealed for all investigated salts as a result of a high supersaturation of the pore solution at the time when crystals grow against the pore wall. Surface roughness measurements were used to compare the extent of damage and to rank the damage potentials of the salts. Investigations on the supersaturation, which is directly linked to the crystallization pressure and is suggested to be used as a quantitative and comparable measure for the damage potential, revealed high values at the onset of crystallization for all salts in cooling (also in porous host materials) and evaporation experiments. The results of this comprehensive study clearly reveal a high damage potential of nitrate salts, formerly often neglected in discussions on damage-relevant salts. • Systematic investigation of the damage potential of various nitrates in building materials. • Supersaturation of nitrate solutions in various porous materials. • Determination of supersaturation by cooling calorimetry. • Accelerated damage test of sandstone contaminated with nitrates. [ABSTRACT FROM AUTHOR]

Presented in this paper is a study on the biopolymer treated recycled glass sand (BRGS). The effect of curing period, temperature, initial mixing moisture content and biopolymer concentration on mechanical behaviors of BRGS were examined through unconfined compaction strength (UCS), consolidated and drained triaxial test and scanning electron microscopy (SEM) analysis. The results revealed that biopolymer had a significant improvement on the soil stability. The mixing moisture content, biopolymer concentration and curing condition had a strong influence on soil strength. The strength of BRGS increased with dehydration, while further addition of biopolymer concentration may result in a decrease in strength. It was found that different types of biopolymers had their own preferences for curing conditions. The strength of agar treated RGS (thermal induced biopolymer) cured at 105 ℃ for 30 days was six times stronger than that cured at room temperature, while the optimal curing temperature of alginate treated RGS (ionic gelation biopolymer) was 50 ℃. The BRGS presented a slight decrease in friction angle but a significant increase in cohesion. The SEM image showing biopolymer uniformly wrapped RGS particles. • Different types of biopolymers were applied on recycled glass sand (RGS) to develop sustainable construction materials. • Essential factors that influenced the engineering properties of biopolymer treated RGS were studied. • The interaction between three different biopolymers and recycled glass sand are investigated. • Potential applications of recycled glass sand with biopolymer treatment on the construction materials are discussed. [ABSTRACT FROM AUTHOR]

• A systematical review of 3D printable cementitious materials was conducted. • A multi-level material design (MMD) for development of 3DPCM was proposed. • MMD is illustrated via inter-connected pyramids, i.e. material, printing & structure. • Based on MMD, three different levels of material design are reviewed successively. 3D printing, or additive manufacturing, is a technology which adopts layer-by-layer additive deposition process to build three-dimensional objects. Over the past decade, 3D printing has been attracting more and more attention in the building and construction industry. Compared with conventional concrete casting techniques, 3D printing contributes to higher efficiency with freeform construction, greatly reduced labor and much less construction waste. However, 3D printable cementitious materials are different from conventional concrete in terms of rheology, printability, and mechanical performances. This paper aims to systematically bridge the gap between the requirement and research and development of 3D printable cementitious materials to date. Guided by 3D printing process and multi-level design of cementitious materials, the requirements for 3D printable cementitious material at different material development levels are discussed. This paper provides insights for the future development of 3D printable cementitious materials for building and construction by controlling the basic inputs of materials to obtain desired structural performance. [ABSTRACT FROM AUTHOR]

Highlights • The paper presents a literature review of healing agents for cementitious materials. • Strategies to deliver the healing agent into the concrete are discussed. • Mechanical and long-term performance of healing agents are analysed. • Evaluation of healing efficiency methodologies is presented. • Life cycle cost analysis of conventional vs. healed concrete is discussed. Abstract Concrete is a widely used material in the construction industry due to its affordability and availability; however, it is also sensitive to crack formation typically under tension stresses. Due to cracking, the durability of concrete is compromised via contaminant ingress such as rapid chloride penetration and atmospheric water that infiltrate through these cracks and potentially lead to corrosion of steel in reinforced concrete. Self-healing materials embedded in cementitious materials is emerging as an innovative method to improve concrete durability. This paper reviews available self-healing approaches considering various healing materials with respect to performance and application. Attention to the efficiency of healing materials including biotechnological, polymeric and chemical components for crack healing and improvement in strength is a major focus. Consideration is also placed on methods of testing, evaluation methods for calculating efficiency and comparison of self-healing materials and their efficiency. Finally, a conceptual life-cycle cost for conventional and self-healing concrete structures is provided. [ABSTRACT FROM AUTHOR]

Highlights • CNTs and CNFs are both the nano-structured fibrous materials with excellent properties. • The dispersion of CNTs/CNFs is the decisive factor affecting the performance of composites. • The incorporation of CNTs and CNFs affects the variety performance of cement-based materials. • CNTs/CNFs-modified cement-based composites have broad application prospects. Abstract CNTs and CNFs are drawing widespread attention due to the unique structure and excellent properties, such as the mechanical property and the electrical property. It will significantly improve the cement-based composites' properties when adding CNTs/CNFs into composites. This paper briefly introduces the CNTs'/CNFs' basic properties and dispersion methods, and elucidates the properties of cement-based composites recombining CNTs/CNFs, including the mechanical property, the deformation property, the durability property, the thermal conductivities and electrical conductivities. This paper also summarizes the problems existing in present research, and gives some proposes for future study. [ABSTRACT FROM AUTHOR]

Highlights • Compressive strength at high temperatures of fibre concretes studied. • Influence of the high temperatures on the physical and chemical changes of the concrete studied. • Behavior of the new Dramix 5D steel fibre concretes in fire studied. • Model for compression strength at high temperatures of fibre concrete proposed. Abstract The high temperatures of fires affect the physical and chemical properties of the concrete and thus influence its mechanical properties. This paper presents the results of an experimental investigation on the compressive strength at high temperatures of high-strength fibre concretes. The influence of the high temperatures on the physical and chemical changes of the concrete was also analysed by Thermo Gravimetric Analysis/Differential Thermal Analysis (TGA/DTA), X-Ray Diffraction (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectrometry (SEM/EDS). Five concrete compositions with different steel fibre contents and types have been tested: one without steel fibres (reference composition), two with Dramix 3D steel fibres and two with Dramix 5D steel fibres (45 and 75 kg/m3). This new type of steel fibres, the Dramix 5D, presents a double curvature at its ends, allowing a more efficient anchorage in the cementitious matrix. The behaviour at high temperatures of concretes made with these 5D fibres has been compared with the one of concretes made with the Dramix 3D steel fibres. Therefore, the impact of the high temperatures on the compressive strength and morphology of the high-strength fibre concretes made with the Dramix 3D and 5D steel fibres has been evaluated. The paper proposes also models for the compressive strength at high temperatures of the studied high strength fibre concretes. [ABSTRACT FROM AUTHOR]

Highlights • The long-term behavior of cement paste is studied experimentally and analytically. • An analytical scheme is developed to estimate the chloride diffusion coefficient. • The analytical scheme is verified with eight sets of experimental data. Abstract The intention of this paper is to estimate the steady-state chloride diffusion coefficient of mature cement paste through laboratory test and theoretical analysis. In the test, the chloride diffusion coefficient of cement paste with water/cement ratios of 0.3, 0.4, 0.5, and 0.6 is measured at curing ages from 28 to 1800 days. The test results show that, for cement paste cured for smaller than 360 days, the chloride diffusion coefficient reduces quickly with the increase of curing age. For cement paste cured for larger than 360 days, however, the chloride diffusion coefficient decreases slowly with increasing the curing age. In view of the multi-phase and multi-scale characteristics of cement paste, a three-step scheme is developed to derive the chloride diffusion coefficient analytically. In the scheme, the chloride diffusion coefficients of the inner and outer hydration products and the solid phase are formulated with a two- and three-phase composite sphere models, respectively. Finally, for the bi-continuous cement paste system composed of a solid phase and capillary pores, the effective medium method is adopted to deduce the chloride diffusion coefficient. Eight sets of experimental data, obtained in this paper and collected from the literature, are used to verify the analytical scheme. It is concluded that the developed three-step analytical scheme can evaluate the chloride diffusion coefficient of mature cement paste with reasonable accuracy. [ABSTRACT FROM AUTHOR]

Highlights • This paper presents a new fracture model for describing the ice materials. • The model was combined with energy method and Gurson's model. • The new model can help compensate for the lack of research on the fracture law of ice material. Abstract The cracking and fracture behaviour of ice material in cold regions significantly affects the mechanical properties of concrete material and structures due to ice pressure or the ultimate load carrying capacity. The mechanical performance of ice material depends on the characteristics of ice crystals, ice depth, temperature and geographical distribution in different regions. The main objective of this paper was to propose an innovative model for describing the fracture toughness of ice material subjected to different geographical distributions, depths and temperatures based on the energy balance theory, the generalized self-consistent method and Gurson's damage model, and the model results were then compared with experimental results and those of Ji. In addition, according to statistical theory, an equation for calculating the variance of the fracture behaviour of ice material was established based on the fracture flexibility results for determining the mechanical properties of the ice material. [ABSTRACT FROM AUTHOR]

Highlights • Influence of nanoparticles on the properties of cement-based materials is discussed. • Nanoparticles can significantly alter the hydration mechanism of cement paste. • Research needs are identified based on the gaps in the current state of knowledge. Abstract This review paper intends to synthesise the data published in the literature on the uses of different types of nanomaterials in cementitious materials. According to ASTM, depending on types, the size of nanoparticles varies from 1 nm to 100 nm. Application of nanomaterials in different sectors has shown that the properties of conventional materials can be significantly improved when nanoparticles are included. The addition of nanoparticles in cementitious materials can act as a filler agent, producing a dense matrix and reduce the growth of micro pores. Some nanoparticles also help in the secondary reactions forming cement composite and contribute to the strength development. Moreover, this paper summarises the current knowledge of the microstructure, mechanical strength and durability of cementitious materials when incorporating different types of nanoparticles. In addition, research needs are identified based on the gaps in the current state of knowledge on using nanoparticles in cement-based construction materials. [ABSTRACT FROM AUTHOR]

Highlights • Effects of glass fiber on mechanical properties of MPC were studied. • The addition of glass fiber improved the water resistance of MPCs. • The flexibility and deformation behavior of MPC can be improved by using glass fiber. • The mechanism of glass fiber improving water resistance of MPC was analyzed. Abstract This paper describes an experimental investigation into the compressive strength, the flexural strength and the water resistance of magnesium phosphate cement (MPC) mortar reinforced by glass fiber. Fiber volume fractions of 1.5%, 2.5%, 3%, 3.5% and binder/aggregate ratios of 1:1, 1:1.2 and 1:1.5 were designed for the experiments. The microstructural, mechanical and water resistance properties of fiber-reinforced MPCs were evaluated with respects to the variance in the fiber volume fraction, the ratio of binder/aggregate. The results showed that the glass fibers have more pronounced effects on the flexural strength compared to compressive strength. The optimum volume fraction of glass fiber is reported at 2.5%. Furthermore, the effect of glass fiber on the water resistance of MPC is discussed, and a "reserving" method to resist the strength loss by water has been proposed. In addition, the paper provides a possible explanation of the fiber reinforcement mechanism which is in agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Highlights • Two types of alternative bricks, namely material-oriented and process-oriented. • Geopolymerisation is a preferable way to produce bricks. • Clay-based geopolymer bricks can be one of the focuses of brick-related research. • The key challenge is to improve the reactivity of clay at a low cost. Abstract Bricks have been playing a significant role in building and construction for thousands of years. Despite the reliable workability and accessibility, it is widely known that the production of fired clay brick has always been a rather energy- and resource-intensive process. Many researchers have been conducting a wide range of studies regarding sustainable and innovative bricks, to mitigate the large carbon footprint of brick industry. To better understand the development and current context of sustainable and innovative bricks during the past several decades, this paper provides an up-to-date review on the recent studies of bricks, categorising these publications according to the materials used and methods employed for the production of innovative bricks. This review found that firing is still the most common method to produce bricks, while this process involves enormous energy consumption and carbon footprint. Considering that cement and lime-based calcium-silicate-hydrate bricks are also not sustainable, Geopolymerisation is a preferable way to produce bricks, but corresponding cost and benefit analyses need to be conducted for relevant research. In addition, this paper suggests that clay-based geopolymer bricks could be one of the focuses of future brick-related research, and the key challenge is to improve the reactivity of clay at a low cost. [ABSTRACT FROM AUTHOR]