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Natural rubber latex (NRL) and cellulosic fibre are promising additives for improving the performance and sustainability of cement composite. This study investigated the optimised inclusion of NRL into waste paper pulp (WPP)-ordinary Portland cement (OPC) composites to enhance mechanical and durability properties. Three mixing methods were compared, revealing pre-mixing WPP with OPC before adding diluted NRL as the most effective. Both high-ammonia NRL (HA-NRL) and prevulcanised NRL (PV-NRL) significantly reduced water absorption, with PV-NRL slightly outperforming HA-NRL. Flexural properties were optimised at an NRL/OPC/WPP ratio of 10/700/300 parts by dry weight, although excessive NRL content reduced modulus. NRL also enhanced fire resistance through a synergistic effect, forming an ash-char layer, with HA-NRL exhibiting superior performance due to chemical distinctions. Failure modes and crystal formation were analysed using FE-SEM. Overall, optimised NRL and WPP incorporation improved water resistance, flexural performance, and fire resistance, suggesting their potential for sustainable construction. Further research could explore additional performance aspects and optimise NRL and WPP dosages for broader applications. • NRL incorporation significantly enhances flexural strength and modulus, promising structural applications. • Optimised composite formulations with natural rubber latex and waste paper pulp offer sustainable construction materials. • Synergy between NRL and waste paper pulp enhances fire resistance, resulting in the formation of a ash-char layer, suggesting suitability for fire-prone environments. • Exceptional water resistance ensures durability and resilience against moisture-induced degradation. [ABSTRACT FROM AUTHOR]

In recent years in India, fly ash-lime-gypsum (FaL-G) brick production has been adversely affected by the scarcity of fly ash and lime. Consequently, the current study aims to mitigate this problem. It delves into leveraging incinerated paper mill sludge ash (IPMSA) as a supplement to fly ash and lime in FaL-G brick production, aiming to present an eco-conscious alternative to conventional burnt clay bricks. It focuses on two blends: blend 1, replacing fly ash with IPMSA (2.5–30 wt%), and blend 2 substituting lime entirely with IPMSA (2.5–15 wt%). A thorough material analysis preceded brick manufacturing, involving techniques like energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, thermogravimetry differential thermal analysis, scanning electron microscopy, and X-ray diffraction spectroscopy. Subsequent tests evaluated compressive strength, water absorption, weight density, percentage of voids, initial rate of suction and chemical resistance of the resulting bricks. According to the XRD results, the higher IPMSA levels didn't induce any phase transformation. Remarkably, bricks incorporating IPMSA in blend 1 (2.5–20 wt%) and blend 2 (2.5–7.5 wt%) met the mechanical properties specified for 'class 10' bricks according to Indian and ASTM standards. Incorporating IPMSA increases the porosity of bricks, making them lighter. This aids in minimizing construction expenses by reducing labour and transportation costs as well as lowering expenditure on foundation construction. This sustainable approach efficiently uses resources, reduces landfill wastes, shows potential for industrial-scale production, making eco-friendly bricks a promising alternative to traditional methods and promoting greener construction practices. • Ecofriendly FaL-G bricks were developed using incinerated paper mill sludge ash (IPMSA). • Reusability of IPMSA in FaL-G brick production poses both economic and environmental benefits. • Use of IPMSA in FaL-G brick production reduces landfill waste and addresses waste management issues. • IPMSA is suitable for up to 20 wt% for fly ash and 7.5 wt% for lime in FaL-G brick production, meeting relevant standards. [ABSTRACT FROM AUTHOR]

This study investigates the impact of incorporating lime mud (LM) as a filler material to develop sustainable, cementless ultra-high performance concrete (UHPC) by replacing silica powder (SP) and silica sand (SS) at varying percentages. Flowability analysis reveals that LM, with its distinctive particle size, influences flow characteristics differently at different replacement levels. Compressive strength was improved by 5.4% with 30% SP replacement, showcasing the role of LM in nucleation, as well as its particle size advantage. The heat of hydration analysis indicates that LM likely influences the early curing stages, enhancing reactivity and nucleation. TGA analysis also confirms that LM plays a role in hydration reaction, influencing weight loss and hydration peaks. The mercury intrusion porosimeter results show the impact of LM on pore distribution, with 30% for SP and 50% for SS replacements, favoring denser matrices. Life cycle assessment (LCA) demonstrates reduced CO 2 emissions and favorable environmental performance, highlighting the sustainability potential of LM replacements. Overall, the incorporation of LM in UHPC shows promise in terms of enhancing its mechanical properties and environmental sustainability. [Display omitted] • Lime mud (LM) in UHPC boosts material strength, leading to denser, more effective concrete. • LM enhances hydration, flowability, and refines pore structure. • High LM ratios in UHPC increase sustainability and reduce CO 2 emissions. • LM's use in UHPC significantly advances its mechanical properties and eco-friendliness. [ABSTRACT FROM AUTHOR]

• Titanate coupling agents reduce particle-polyol mixture viscosity more than 2 times. • Titanate coupling agents form hydrophobic monomolecular layer on the particle surface. • Coupled paper waste particles increase compressive and tensile strengths. • Coupled paper waste particles initiate nucleation process in particle-polyol mixture. Current efforts are focused on transforming renewable resources into advantageous polymers and the utilisation of waste for the same application and others. However, the utilisation of waste into polymer systems causes forming mixtures with high viscosities; therefore, this study analyses different types of titanate coupling agents (TCAs), TCA-L44, TCA-L38 and TCA-K44, and their effects on the rheology of bio-based polyol premixes filled with paper waste particles and the physical-mechanical properties and microstructures of polyurethane foams (RPUFs). It is found that TCAs improve the dynamic viscosity of polyol premixes by a factor of two. Based on the scattering of the apparent density results, TCA-L44 and TCA-K44, at amounts of 1–3 wt%, ensure an even distribution of waste particles, while TCA-L38 does not show evidence of coupling. Compared to RPUF without TCAs, the apparent density increased on average from ∼65 to ∼69 kg/m3 for TCA-L44, to ∼71 kg/m3 for TCA-L38 and to 69 kg/m3, indicating a weak cross-link effect. The compressive strength increases by an average of 6.5–9.1% and the tensile strength increases by 26.0–42.2% when TCA-K44 is used, while the water absorption decreases by up to ∼62% and the water vapour diffusion resistance factor decreases by ∼39% when TCA-L44 is used. [ABSTRACT FROM AUTHOR]

Highlights • Pozzolanic reaction within the novel non-portland binder was compared with OPC. • Conversion of AFt to AFm in the binder was confirmed by TG/DTA and FT-IR analysis. • Reduced density of C-H phase within the novel binder after long term curing revealed. Abstract The development and production of new materials requires advanced analytical characterisation to explain the relation between the physico-chemical structure of the material and its properties. Highly integrated microelectronic structure analysis of surfaces with laser beams and X-ray fluorescence aided devices are found to be helpful for providing important information, including the interrelationships between physical, chemical, mechanical and durability characteristics of the new developed products. In most instances no single technique provides all the needed information and hence simultaneous application of several techniques becomes necessary. This study was aimed for hydration analysis, characterization and evaluation of a new novel non-Portland binder (NPB) with waste paper sludge ash (PSA) using FTIR and TG/DTA. The progressive formation of hydration products within the non-Portland binder was identified and their microstructural characteristics were analysed. The stable and non-expansive nature of secondary ettringite formation was also identified after a period of 365 days curing. [ABSTRACT FROM AUTHOR]

Green liquor dregs wastes coming from pulp and paper production are currently disposed in landfills at a huge cost for industry and the environment. In this work, a novel and more sustainable waste management strategy is proposed. Dregs were used for the first time as fine filler in the production of biomass fly ash-based geopolymeric mortars. The influence of the dregs incorporation amount on the fresh (geopolymer kinetics and mortars workability) and hardened-state (mechanical resistance, water absorption and capillary water absorption) properties of the mortars was evaluated. Although dregs incorporation reduce the flow workability (up to 19%), their presence and amount did not significantly alter the geopolymerization kinetics. Additionally dregs-containing mortars exhibited enhanced tensile (up to 71%) and compressive strength (up to 34%), and lower water absorption in comparison with the reference mortar. These results demonstrate the feasibility of using dregs as fine filler in geopolymers production. Moreover the mortars were produced using mainly biomass fly ash waste as aluminosilicate source which further reduces the environmental impact of the pulp and paper industry. [ABSTRACT FROM AUTHOR]

This paper reports the results of an exploratory experimental study to manufacture eco-friendly lightweight bricks through binary mix of paper mill sludge (PMS) and soil. The pre-manufacture activities include mineralogical, chemical, thermal and index properties characterisation of two kinds of soils (laterite and alluvial) and PMS. The mix ratio between PMS and soil was varied (0%, 5%, 10%, 15% and 20%) and two firing temperatures 850 °C and 900 °C were tested in order to emulate the typical conditions of a kiln. The performance of incorporating PMS into the mix was tested by evaluating properties such as linear shrinkage, compressive strength, water absorption, mass loss on ignition, and bulk density of bricks as recommended by the relevant Indian and ASTM standard codes. X ray diffraction results confirmed that the addition of PMS does not show any phase transformation and only enhances the porosity thereby leading to weight reduction. Based on the results, an optimum mix of 10% PMS with both soil types was found suitable for brick production at a firing temperature of 900 °C. Results obtained in this study will be helpful to brick industry for commercial production of PMS incorporated bricks leading to sustainable use of resources. [ABSTRACT FROM AUTHOR]

• Lignin additive extracted using H 2 SO 4 (L-S) had high phenolic content and pH value. • Asphalt with L-S additive had the lowest reduction of crossover modulus due to aging. • Incorporating L-S into asphalt reduces the increase of asphaltene fraction due to aging. • FTIR test is more sensitive in measuring the lignin antioxidant performance than DSR and GPC. The main objective of this research is to investigate the effectiveness of lignin bio-additives derived from black liquor paper pulp as asphalt antioxidants. Two lignin bio-additives, H-L and S-L, were developed by acidifying black liquor with hydrochloric and sulfuric acid. The laboratory aging procedures used in this study included the Rolling Thin Film Oven and the Ultraviolet Chamber methods. The crossover modulus (|G* c |) and linear amplitude sweep (LAS) were measured using a Dynamic Shear Rheometer (DSR). Gel Permeation Chromatography (GPC) was also used to characterize the molecular size distribution of the asphalt binder. The combination of carbonyl and sulfoxide aging indices was measured using Fourier Transform Infrared (FTIR) spectroscopy. The S-L modified binder (S-LMB) demonstrated superior aging resistance compared to both the control binder (CB) and the H-L modified binder (H-LMB) by exhibiting the lowest reduction in |G* c |. Furthermore, the LAS test results showed that S-LMB provided the best resistance to aging due to the lowest decrease in fatigue life with age conditioning, followed by CB and H-LMB, with rates of 11%, 13%, and 16%, respectively. The GPC results also confirmed the efficacy of the S-L bio-additive as an antioxidant, exhibiting the lowest increment in asphaltene proportion attributed to age conditioning. The FTIR measurements successfully captured the antioxidant capability of both H-L and S-L bio-additives, with S-L performing better than H-L. Overall, the results suggest that S-L demonstrates superior antioxidant performance compared to H-L. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate some physical and mechanical properties of the paper mill (PMS) and spruce planer shaving added cement boards. Also the effect of sludge type in consequence of waste water treatment technique on properties of wood-cement boards (WCB) was investigated. The wood/cement ratios were used as 1/3, based on the oven dry weight for the WCB manufacture. PMS was used up to 20% wt of total composite based on organic (wood) and inorganic (cement) amounts. Black sludge has shown more improvement than grey sludge on properties of WCBs, which indicates the anaerobic waste treatment technique is more effective for additive in WCB. The modulus of rupture and elasticity values of the WCBs with 5% of grey sludge, 5% and 10% of mixture of grey and black sludge were acceptable limits according to EN 634-2 standard. The mechanical strengths of all WCBs with black sludge were found above the specified EN standard. This suggests that PMS depending on sludge type may be used up to 20% wt of total composite weight for the commercial production of WCBs, which could expand the raw material base for this panel product. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate influence of calcination and cooling conditions on pozzolanic reactivity of waste paper sludge. Calcined paper sludge (CPS) is prepared by different temperatures of calcination, duration of calcination and cooling methods. Pozzolanic activity of CPS was investigated by using API (Assessed Pozzolanic Activity Index) and SAI (Strength Activity Index) in accordance with ASTM C618 -17 (KS L 5405) and consumption of Ca(OH) 2 hydrate in mortars with CPS in detail, and compared to that of commercial fly ash (FA) and blast furnace slag (BFS) used in the concrete industry. Results revealed CPS produced from waste paper sludge had excellent pozzolanic activity compared with commercial pozzolanic admixtures such as FA or BFS. Their pozzolanic activity was most excellent in calcination temperature of 700 °C, calcination duration of 2 h and cooling method of water quenching. SAI (%) of mortar with CPS produced under optimal conditions was 96% at 28 days of age, and satisfied the quality of fly ash (Class F) as specified in ASTM C618 -17 (KS L 5405). There was linear relation between API (%) and SAI (%) of mortars with CPS, and the correlation coefficient was relatively good as 0.8 at 28 days of age. The API method is recommended as rapid and appropriate evaluation of the pozzolanic activity of the CPS. [ABSTRACT FROM AUTHOR]

• RCF wastes brick achieves 24% lower thermal properties than the control brick. • RCF wastes brick requires 10% lower firing temperature than the control brick. • Utilizing as-received waste materials requires zero grinding energy, benefiting manufacturers and cutting emissions. • Lower firing temperature saved $158,460 by cutting 417 tonnes of CO 2. Building materials drive the global economy, yet face severe environmental hurdles: resource depletion, greenhouse gas emissions, and waste generation. In order to mitigate the impact from these challenges, authorities seek sustainable and eco-friendly alternatives as an urgent need. This study focuses on the utilization of as-received rejected contaminated fines (RCF) obtained from the yellow bins' waste (paper) recycling process, in brick production. Diverse tests assessed the brick performance, including compressive strength, absorption rate, thermal conductivity, 3D CT scanning for morphological analysis, and durability analysis. Additionally, a leachate analysis was performed to evaluate the environmental implications. Economic benefits, particularly the reduction of CO 2 emissions, were also evaluated. The findings confirmed that as-received waste can be utilized for fired clay brick production without the need for pulverization. The novel brick product made with as-received RCF waste exhibited superior thermal characteristics (up to a 31.25 % reduction compared to control bricks) while meeting the essential compliance requirements outlined by national standards. Moreover, each firing cycle led to a potential value of up to USD 158,460 through a reduction of 417 tonnes of CO 2 , resulting from a 9.5 % reduction in firing temperature (1000 °C). The results from this study offer valuable insights into the potential of using RCF waste as a sustainable alternative in the brick manufacturing industry. This alternative could address the soaring demand in the current market, resolve the escalating solid waste crisis, and mitigate clay shortages, while providing a sustainable solution for the brick industry. [ABSTRACT FROM AUTHOR]

• Combined effects of extruded brick compositions with paper sludge and expanded perlite were characterized. • The use of additives in bricks has significantly affected their thermo-physical and mechanical properties. • The effects of process parameters on brick properties were investigated with a new mathematical modeling approach. • Fired brick samples showed good thermal insulation performance. • Produced exruded bricks have good potential for energy saving. Lightweight bricks produced with addition of different additive materials such as expanded perlite (EP) and recycling paper sludge (RPS) waste have been accomplished by a pug mill. Porous fired bricks were produced by using organic and inorganic additives such as paper waste and expanded perlite as pore-makers. In the experimental study, the seventeen mixture sets were prepared with Box-Behnken experimental design procedure of two additive ratios and firing temperatures. The brick samples were produced with shaping by extrusion method and firing at 850, 950 and 1050 °C for two hours after drying. Physical characteristics such as bulk density, apparent porosity and water absorption, and also, compressive strength, thermal conductivity and microstructural properties of brick samples were studied. Influences of process parameters on brick properties were investigated with a detailed neuro-regression analysis. In conclusion, the best brick composition (10 % EP + 10 %RPS by weight) in terms of thermal conductivity corresponding to acceptable mechanical properties was optimized. Accordingly, the compressive strength values of all samples are around 10 to 27 MPa. Also, the samples with high additive content (especially 10 %RPS + 5 %EP sample) exhibited the lowest thermal conductivity value (0.432 W/mK) due to the low firing temperature. [ABSTRACT FROM AUTHOR]

In the paper, the impact of paper production waste (primary sludge, or PS) on the properties of cement pastes and mortars is discussed upon. Some specimens were formed with fine PS fraction that replaced a part of cement content in them (5%, 10%, 15%, or 20%); in other specimens, coarse fraction of sludge (2/4) was used and a part of content of fine filler (sand) was replaced by PS. The properties of mixtures, such as water content required for cement paste of normal consistence, the setting time, exothermic temperature, flow diameter and plunger penetration, were established. In addition, the properties of hardened mortar, such as its density, flexural strength and compressive strength, were established. The microstructure of hardened specimens was examined as well. It was found that PS retarded hydration processes and reduced exothermic temperature; in addition, it reduced the flow diameter and the plunger penetration. While assessing the properties of hardened mortar, it may be stated that 5% PS waste might be used for replacement of a part of cement content. [ABSTRACT FROM AUTHOR]

Due to increasing generation of solid wastes from papermaking industry, major concerns arise about the disposal of the solid wastes and their adverse impacts on environments, in which the disposal of paper sludge massively produced from paper mills has become one of the most serious solid waste problems worldwide. In this study, laboratory experiments were conducted to evaluate the feasibility and applicability of incorporating solid wastes from paper mills into controlled low strength material (CLSM), in which fly ash was used as a substitute for cement, bottom ash was added by partially replacing fine aggregate, and paper sludge was treated as a fibrous admixture. Results show that both fly ash and bottom ash could be effectively used in production of CLSM mixtures with desired performances. By limiting the amount of cement used in the mixture, the ultimate strength of CLSM could be controlled for easy excavation. Fly ash could effectively increase flowability of the mixture, thus improving self-compactibility. Both bottom ash and paper sludge had an adverse effect on the flowability. The strength of CLSM was reduced when a higher content of fly ash was incorporated to replace cement, while the strength was increased when more river sand was replaced with bottom ash. Due to a high water absorption and poor dispersibility of paper sludge, the CLSM made with additional paper sludge exhibited a relatively low flowability and a reduction in strength. However, with proper mixture design, paper sludge could still be effectively used in CLSM. [ABSTRACT FROM AUTHOR]

In the present work, unshredded waste newspaper based composites have been prepared in polyester resin matrix. Reinforcing material, waste newspaper is characterized by chemically, X-ray diffraction (XRD) methods, Fourier transform infrared spectroscopy (FTIR) and tensile properties. Three different fibre content composite samples, namely 25%, 34%, and 50% (by weight) are prepared by hand lay-up techniques. Water absorption and thickness swelling tests are conducted by immersing composite samples in distilled water at room temperature. It is found that the percentage of moisture uptake and thickness swelling are increased as the fibre volume fraction is increased due to the high cellulose content. The tensile, flexural and interlaminar shear strength properties of water immersed samples are investigated and compared with dry composite samples. It is observed that after swelling the mechanical properties of composites are found to decrease with increase in percentage moisture uptake. [ABSTRACT FROM AUTHOR]

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]

The paper analyses the effect of waste sludge from paper industry (paper sludge) on physical and mechanical properties of clay bricks, their microstructure and resistance to freezing and thawing. Paper sludge is not hazardous industrial waste mainly consisting of cellulose and calcite. Clay bodies were made from the mix containing from 5% to 20% of paper sludge and fired at 900 °C and 1000 °C temperatures. Open pore structure in the clay body is developed as a result of burnt cellulose fibres and calcite decarbonization. Physical and mechanical properties of clay bodies change depending on the content of added PS: shrinkage, density and compressive strength reduce, water absorption and effective porosity increase. It is recommended to add 5% of paper sludge to the clay body and fire it at 900 °C temperature, or alternatively add 5–15% of paper sludge and fire the clay body at 1000 °C temperature. In terms of resistance to freezing and thawing, such products are regarded as frost resistant in moderately aggressive environment, i.e. in structures protected from direct environmental effects. [ABSTRACT FROM AUTHOR]

• Long-term natural environment experiments of composite ice were performed. • The cumulative effect of composite ice sublimation rate was explored. • A dynamic model for composite ice sublimation prediction was proposed. • The changes in the mechanical properties of composite ice were tested. The climatic adaptability of ice-shell architecture under long-term natural influence remains underexplored. This study investigates the weatherability of paper fiber reinforced ice (PFRI) as envelopes, including the changes in the sublimation mechanism and mechanical properties changes. The PFRI specimens were layered poured and exposed to nature. The sublimation rates, climatic parameters, and stress–strain data were recorded. The results suggest that PFRI sublimation is a dynamic process with cumulative effects. A calculation model is proposed to predict sublimation in engineering. Considering fibre escape, PFRI with 2% or 3% fibre content has better weatherability, with a 30% decrease in elastic modulus on the sunny side and a 15% decrease on the shaded side. [ABSTRACT FROM AUTHOR]

The paper characterizes waste in the form of fly ash generated in a power plant during the combustion of biomass in a fluidized bed in terms of its possible use in the ceramic building materials industry. This is important from the point of view of environmental protection. In order to assess the possibility of using ash in the production of red ceramics (e.g. bricks), two different clay raw materials (Clay I and Clay II) were selected to prepare the raw material sets. First of all, the investigated fly ash was subjected to thermogravimetric TG-DTG analysis and its basic chemical composition was determined. Then the specific density was determined for all the raw materials, XRD analysis was also performed and finally characteristic temperatures were determined by means of a high-temperature microscope. The basic raw material sets included clayey raw material and fly ash in various contents: 5 wt%, 10 wt% and 15 wt%. Samples were pressed from the ready sets and fired at the temperature of 1000℃. Afterwards, the obtained samples were subjected to XRD and microstructural tests, then selected physical properties were determined, i.e. water absorption, porosity, apparent density, and compressive strength. Based on the research and analysis of the results, it was found that the introduction of fly ash from biomass combustion into the raw material set in the range of 5–15 wt% has a positive effect on the insulating properties of red ceramics. In addition, the density of the red ceramics decreases with the increase in the addition of fly ash, while its porosity and water absorption increase. Furthermore, the addition of fly ash decreases the compressive strength and visually brightens the microstructure of the products. • It is possible to use fly ash from combustion in the production of red ceramics. • The sintering process transforms dusty waste into a harmless product. • The addition of ashes to clay reduces the density of finished products. • Products with the addition of fly ash have higher porosity. • Ceramic products with the addition of ashes are full-value products. [ABSTRACT FROM AUTHOR]

A raw decorative paper was coated with a mixture of TiO 2 -SiO 2 nanocomposite aerogel and melamine-formaldehyde resin to achieve dual functions, namely formaldehyde degradation and smoke suppression. The physical and chemical structure of TiO 2 -SiO 2 nanocomposite aerogel and its photocatalytic activity on liquid formaldehyde degradation were revealed. Moreover, the coated melamine-impregnated paper was further decorated into the surface of a poplar wood veneer to prepare a real indoor panel. A self-designed sealed box and cone calorimeter were used to test its photocatalytic activity on gaseous formaldehyde degradation and smoke suppression. The results showed that the presence of massive mesopores in TiO 2 -SiO 2 nanocomposite aerogel and the appearance of anatase nanocrystal of TiO 2 synergistically lead to both the high liquid and gaseous formaldehyde degradation rates of 65.8% and 56.6%. In addition, the porous structure and incombustibility of TiO 2 -SiO 2 nanocomposite aerogel also result in high smoke suppression, demonstrating the maximum decrease in CO and CO 2 production by 56.2% and 33.2%. The preparation process of the coated melamine-impregnated paper is easy to realize industrial production. After decorated into the surface of wood-based panels, it can be used as the indoor materials of wall, floor, and furniture. [ABSTRACT FROM AUTHOR]

This review compiles the main scientific and technical findings on the viability of using paper sludge waste as a supplementary cementitious material in the manufacture of future eco-efficient cements. It contains a detailed analysis of the scientific (characterisation, activation conditions, pozzolanic activity, system reaction kinetics) and technical (rheology, physical and mechanical properties, and resistance to chlorides, sulphates, sea spray and CO 2 ) properties of this type of waste when used as a supplementary cementitious material. On the grounds of the literature reviewed, paper sludge waste can be confirmed to be an environmentally sound source of recycled metakaolinite, a conclusion with significant social and economic benefits. [ABSTRACT FROM AUTHOR]

A sandwich structure consisting of perlite composite foam as core and Brown paper as skin is developed and its flexural behaviour is studied in relation with properties of constituents and manufacturing variables of perlite composite foam core consolidated with sodium silicate binder by compaction. Tensile properties of Brown paper coated with binder were affected by sodium silicate content in diluted binder. The best performance of the Brown paper was found for strength and energy absorption when coated with undiluted binder. The sandwich structure was fabricated with the best performed Brown paper and perlite composite foam cores with various binder contents and compaction ratios. The performance of the sandwich structure for core shear strength, skin normal strength, and stiffness was similarly affected by manufacturing variables to those of perlite foam core. Load carrying capacity of perlite foam core reinforced with Brown paper for the sandwich structure was increased about 3–7 times the unreinforced one depending on how binder and compaction ratio are combined for manufacturing perlite foam core. The flexural failure of perlite composite foam core was initiated from the tension side of the flexural specimen. However, when the foam core was sandwiched with the Brown paper, the failure initiation site was shifted to the mid-plane of flexural specimen. [ABSTRACT FROM AUTHOR]

• 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]

• The usability of a paper mill sludge compost (PMSC) in the brick making is established. • Up to 10 wt% of PMSC was suitable for bricks production as per relevant standards. • It is proved that the products can be used in non load-bearing and infill walls. • TCLP procedure demonstrated the non-hazardous nature of the obtained bricks. This study's focus was to develop a potential pathway for recycling of the paper mill sludge compost (PMSC) in brick making. Composting reduces the paper mill sludge (PMS) moisture content considerably and shredding becomes easier. The addition of PMSC leads to an increase of porosities in bricks and makes them lighter, besides delivering energy to the firing process from burning organics. Lighter construction materials help minimize construction outlay by reducing labour and transportation costs and lesser expense on foundation construction. The variability in the experimental data and the brick properties were investigated for two types of soils, typical in the brick industry of India (alluvial and laterite soil), blended with PMSC in five mix ratios (0%, 5%, 10%, 15% and 20%). The samples of oven-dried bricks were fired at two different temperatures (850 and 900 °C) in an electrically operated muffle furnace representing typical conditions of a brick kiln. Various properties of bricks were analyzed which included linear shrinkage, bulk density, water absorption and compressive strength. Conclusions were drawn based on these properties. It was found that the addition of PMSC to the alluvial and laterite soil by up to 10% weight yield mechanical properties of fired bricks compliant with the relevant Indian and ASTM codes. Toxicity characteristic leaching procedure (TCLP) tests showed that PMSC incorporated fired bricks are safe to use in regular applications as non-load-bearing and infill walls. This study is timely in light of the European Green Deal putting focus on circular economy. Besides, it fulfills the objective of UN sustainable development goals (SDG). [ABSTRACT FROM AUTHOR]

• An innovative viscosity-modifying admixture (VMA) is produced from paper pulp. • The versatility of using milled paper pulp as a VMA in cement composites is validated. • The mechanism of viscosity modifying action of milled paper pulp is elaborated. • A new parameter is proposed to quantify nonlinearity induced by VMAs. In this paper, we report the performance of paper pulp as an innovative viscosity modifying admixture (VMA) for cement composites. Two different levels of fineness were obtained by mechanical milling of the same source of paper pulp. Their effects on viscosity modification, hydration kinetics, autogenous shrinkage, and compressive strength of cement grouts were measured, and their structural integrity at high pH was assessed. A new parameter was proposed to quantify nonlinearity induced by VMAs. Results showed that the hierarchical structure of paper pulp makes it possible to activate bridging flocculation and swelling mechanisms of hydrophile paper pulp fibers at different levels to produce versatile VMAs. The coarser milled paper pulp fibers mainly influences the plastic viscosity. By contrast, the milled paper pulp consisting of ultra-fine fibers significantly modifies both plastic viscosity and dynamic yield stress, induces more nonlinearity in the mixtures, and increases compressive strength of mortars at low dosages. [ABSTRACT FROM AUTHOR]

This study is the first step of a research program organized to contribute to the dream of using recycled paper as a structural element for sustainable design in Civil Engineering. One of the important tasks is to understand the behavior of connections in paper materials. This study presents the results of experimental research carried out to investigate the behavior of paperboard laminate connections consisting of a single bolt in double shear. A simple and effective method to predict the bearing strength in bolted connection for paperboard laminates has been proposed. A total of 96 bolted connections were fabricated from paperboards oriented in both machine and cross direction. The effect of end distance and edge distance of bolt hole are investigated to address the limiting value for both variables. It was found that the failure is governed by both shear and bearing stresses developed around the hole. Finally, a straightforward design equation has been proposed for such connections. • Single bolt connections can be implemented on paperboard laminates. • Minimum end distance, and edge distance values should be 1.5 times the hole diameter. • Mixed-mode failure which is the combination of shear and bearing mode will govern. • Equation with max. radial compressive stress can be used conservatively for design. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hydrophobic building material was produced as an alternative to natural wood. • Heat transfer coefficient reduced with various combinations. • A material with high compressive strength was obtained. • The material environmentally friendly is produced from biomass waste. This study aimed to produce a construction composite material that is environmentally friendly, easily accessible, inexpensive and renewable and provides thermal and water insulation. Waste papers, hazelnut shells, pinecones and sheep wool were used at the production stage. The filling rates of the materials were optimized using the RSM. A hydrophobic surface-active substance was used to reduce water absorbability, microbial activity and mold formation. It was observed that these specimens' contact angles were 84° to 146°, thermal conductivity were 0.0511 to 0.0861 W/mK and densities were 0.678 to 0.99 g/cm3. As a result of the compressive and flexural strength tests, it was found that the compressive strength of the specimens was very high, the highest compressive strength was found as 32.8093 N/mm2 in the specimen N25, and the highest flexure strength was found as 6.352 N/mm2 in the specimen N20. A completely environment-friendly, biodegradable and low-cost material was produced out of biomass wastes. [ABSTRACT FROM AUTHOR]

• Paper sludge ash-based stabilizer (PSAS) is a new type of soil stabilizer. • The W ab and PSD of PSAS influence the change in consistency PSAS-treated soil. • The q c of PSAS-treated soil can be estimated based on its liquidity index I L. • Required PSAS amount for a specific q c of PSAS-treated soil can be estimated. Paper sludge ash-based stabilizers (PSASs) have recently been developed in Japan as sustainable construction materials for soil stabilization. PSASs are produced by the in-solubilization of heavy metals in paper sludge (PS), which is generated as a by-product of the de-inking and re-pulping of paper. PSASs can improve the stability of high-water-content clays immediately after mixing owing to their good water absorption and retention performance. However, mixture design methods that consider time variations of the water absorption and retention performance of a PSAS are lacking. Therefore, in this study, the effects of a PSAS on the physical and mechanical properties of the treated clay were experimentally investigated, considering the change in the water absorption and retention performance of the PSAS with curing time. The water absorption and retention rate, W ab , of the PSAS, is defined as the ratio of the mass of water absorbed and retained by the PSAS to its dry mass. Physical tests and cone index tests were conducted on different types of clays treated with different types of PSASs. The test results showed that different W ab values were obtained depending on the type of the PSAS and that the W ab value increased with curing time. From the experiments, it was found that the liquid limits, w L , and plastic limits, w P , of the PSAS-treated clays with different curing times could be evaluated from the W ab values of the PSAS and the particle sizes of the PSAS and untreated clays. A clear correlation was also found between the cone index, q c , and liquidity index, I L , of the treated and untreated clays. Based on the results, a new approach for mixture design was proposed. The applicability of the proposed method was investigated, and the results showed that the measured q c value of the PSAS-treated clay was close to the target q c value. The average measured q c was approximately 1.1 times the corresponding target q c. The maximum error between the measured q c and target q c values was approximately 30%. [ABSTRACT FROM AUTHOR]

• The active silica and waste used have left the pervious concrete more sustainable. • All the mixtures had a high degree of permeability (>3600 mm/h). • Pervious concrete makes space above the pavement less hot because it radiates less. • There is a reduction of flooding in much paved urban areas, increasing groundwater. • The numerical simulation showed an adequate behavior for traffic of light vehicles. Sustainable pervious concretes were developed using waste from the paper industry so to lower cement use in public sidewalks and footways. Pervious concretes with 5 and 10% of industrial waste (WPI) in replace of Portland cement were produced. Flexural tensile strength and compressive strength measured were used to verify, through a numerical simulation, the flexural stress of a 0.7 × 0.8 × 0.1 m pervious concrete plate. Porosity, permeability coefficients of the plates, as well as their thermal conductivity were determined. As a result, compressive strength was reduced, flexural tensile strength was not influenced. Mixtures presented high degrees of permeability (over 3600 mm/h), and potentially reduce CO 2 emissions in cement production, for the proposed use. The pervious concrete with 5% of WPI showed the lowest thermal conductivity (0.798 W/mk), inferior to the thermal conductivity of conventional impervious concrete (1.518 W/mk). The blended pervious concrete can be used where low compressive strength is admitted. [ABSTRACT FROM AUTHOR]

• Recycled Paper Mill Sludge as a filler in asphalt mixture is a feasible practice. • Recycled Paper Mill Sludge modified mixtures requires less asphalt binder content. • The optimum sludge content of 0.5% have been chosen as the most practical rate. • The elemental composition and mineralogical compound of sludge were assessed. • The incorporation of sludge comparatively improved the performance of mixture. As a developing nation that moves towards the sustainability, initiatives had been taken to address the solid waste disposal problem by incorporating them into asphalt pavement construction. This study integrates the recycled material named Recycled Paper Mill Sludge (RPMS) into the production of asphalt mixture as modifier through the partial substitution of mineral filler. The usage of solid waste material in pavement construction could substantially reduce the waste production and reduces the possibility of those waste materials ending up on landfills. This paper evaluates the microscopic analysis such as XRD, XRF and the mechanical properties of asphalt mixture with the incorporation of Recycled Paper Mill Sludge (RPMS). Mechanical properties that were evaluated were indirect tensile strength (ITS), moisture sensitivity, resilient modulus, Leutner shear and dynamic creep. RPMS was added to the asphalt mixture through dry process at the rate of 0.5% and 1%. Addition of RPMS at specific rate improved the mechanical properties such as resilient modulus, Leutner shear and dynamic creep of asphalt mixture. The lapped antenna like fibre of RPMS improved the resilient modulus of asphalt mixture by acting as a reinforcing material. Furthermore, RPMS contains calcite compounds that promote the adhesion bonding between asphalt binder and aggregates which significantly improved the performance in Leutner shear test and dynamic creep test. [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]

• 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]

• 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 use of recycled paper in HDPE (High Density PolyEthylene) matrix composites has recently been introduced as an interesting alternative to traditional recycling process for paper. HDPE is also used as double wall greenhouse glazing because panels are easy to install, UV stabilized, and affordable. These type of products must also be strong enough and durable in order to react under tensile loads provided by wind and harsh weather conditions. An interesting idea may be the insertion via injection moulding of chopped basalt and waste paper – i.e. , two natural products – in pure HDPE samples. It completely follows the environmental sustainability concept centred on the triple “ re ”, i.e. , re cycle, re use and re duce. The research presented herein starts with a Differential Scanning Calorimetry (DSC) inspection of pure HDPE and HDPE mixed with 5% by weight of waste paper plus 5% by weight of chopped basalt as fillers in order to obtain an insight related to the temperature at which possible thermal events (endothermic or exothermic) occur. The dog-bone samples were also inspected under UV conditions (380 nm) before and after tensile tests. The latter approach was simulated firstly by Comsol Multiphysics® computer program, and secondly recorded in real time via thermographic inspections. The temperature variation in a region of interest (ROI) selected at the centre of the samples was mapped in the time during the inspection by infrared thermography (IRT) method using a pseudo-static matrix reconstruction algorithm realized in Matlab® environment. Instead, the combined use of thermocouples aimed at emphasizing the knowledge of the heat transfer in the time due to the mechanical stress applied at the borders of the inspected samples. The aim was to understand whether modified HDPE can (or cannot) be a valid competitor of pure HDPE for the production of semi-transparent and robust panels. [ABSTRACT FROM AUTHOR]

• Potential of using a PSAS to improve the properties of sand for use as a backfill material. • Appropriate water content w of the PSAS-treated sand reduces the swelling potential of PSAS treated sand. • Significant lower strength development of PSAS-treated sand compared with OPC-treated sand under same mixing conditions. • PSAS-treated sand is a suitable replacement of OPC-treated sand. • XRD profiles show that the formation of CaCO 3 is dominant in the PSAS-treated. The aim of this study is to investigate the potential of using a paper sludge ash-based stabilizer (PSAS) to improve the properties of sand proposed to be used as a backfill material around underground pipes. The swelling potential and strength of the sand treated with PSAS are investigated by conducting a series of laboratory tests. Similar tests are conducted on sand treated with ordinary Portland cement (OPC). Swelling potential tests show that the PSAS-treated sand with a water content of 0% show significant expansion during soaking, similar to the OPC-treated sand. However, the test results reveal that an appropriate moisture content of the PSAS-treated sand reduces its potential for expansion, depending on the duration of its temporary placement at the construction site. Unconfined compression tests show that the compressive strength of the PSAS-treated sand is significantly lower than that of the OPC-treated sand under the same mixing conditions, even though the chemical composition of PSAS is relatively similar to that of OPC. The increase in compressive strength with the curing time is more gradual in the PSAS-treated sand than in the OPC-treated sand, suggesting that the former is easier to re-excavate. X-ray diffraction profiles showed that the formation of calcite is dominant in the PSAS-treated sand, and that berlinite may be an additional contributor to the increase in strength of PSAS-treated sand in the long term. [ABSTRACT FROM AUTHOR]

• Recovery of waste paper which is waste presenting disposal and storage problems. • Production of a new product which is a lighter and less dense brick. • The production of bricks with paper waste complies with environmental regulations. • Immobilization of heavy metals contained in waste paper in the ceramic matrix. The deinking paper sludge (DPS) generated by paper recycling incorporated in ceramic pastes has received significant attention to develop environmentally-friendly construction materials with a good thermal and sound insulation characteristic while maintaining a resistance mechanical acceptable by standards. The environmental risks associated with the incorporation of these sludge into clay bricks that rich in heavy metals such as Cr, Pb, Zn, Cu, Ni, etc. have been evaluated. The evaluation of these metals was carried out by performing the leaching test in order to be able to introduce this new material in the list of materials to be marketed in the field of civil engineering. Leaching tests were performed on clay, DPS and the finished product as fired bricks. Leaching results on clays show that they are non-hazardous products, while heavy metal leaching of DPS is above the limiting concentrations, which classifies DPS as a hazardous waste. In contrast, the leaching concentrations of the bricks incorporated by DPS, show that the heavy metals were immobilized in the ceramic structures of all the fired bricks. In this study, the percentages of DPS added in the composition of the bricks are 8%, 10% and 12%. Results of leaching test suggest that replacing up to 12% of clays with DPS can provide bricks to reduce the environmental impact of abundant waste and preserve non-renewable natural resources. [ABSTRACT FROM AUTHOR]

The increasing global waste generated by industrial activities poses significant environmental challenges. Eco-waste management emerges as an economically viable solution for converting, valorizing, and repurposing these byproducts, aligning with circular economy principles, and aiming to reduce greenhouse gas emissions. Construction, known for its unsustainability due to high energy consumption, non-renewable resource utilization, waste generation, and greenhouse gas emissions, particularly from cement production, has led to the exploration of alternative materials. Magnesium oxide (MgO)-based cement, an alternative to Ordinary Portland Cement (OPC), has gained attention, leveraging Brazil's prominence as a major magnesite producer. This study explores the valorization of waste from kraft pulp mills of the paper industry, specifically lime sludge (LS) and lime slaker grits (grits), to produce magnesium oxysulfate (MOS)-based fiber cement boards. The effect of accelerated carbonation on cementitious composites produced with formulations containing grits and LS was investigated. Replacing 25% of the limestone with grits showed no noticeable differences in the properties of the boards, and MOR values close to 11.17 MPa were obtained. However, the physical-mechanical performance showed a decrease with the use of LS and higher concentrations of grits, associated with Na 2 SO 4.XH 2 O formation in the system and ITZ structure formed around the aggregated particle, respectively. Carbonation in a saturated atmosphere led to the carbonation of the 5–1–7 phase, which was related to the decrease in mechanical strength of the boards after the curing process. The thermal decomposition of the Hydrated Magnesium Carbonates (HMCs) formed during accelerated carbonation corroborated with the changes in the physical properties of the composites, demonstrating that the carbonation products are formed within the voids and pores of the material and contribute to the reduction in water absorption of the boards. • Global waste requires innovative environmental solutions for sustainability. • Investigation on eco-waste management aligns with circular economy principles, reducing environmental impact. • Article focuses on MgO-based cements as an alternative to Ordinary Portland Cement, highlighting global magnesite production. • Research emphasizes valorization by utilizing waste from kraft pulp mills (such as LS and grits) for MOS-based fiber cement production. • Exploration of accelerated carbonation impact on cementitious composites with LS and grits unveils shifts in physical-mechanical performance. [ABSTRACT FROM AUTHOR]

• 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]

• A new type of paper-free and fiber-free plasterboard was prepared. • Waste phosphogypsum was the sole raw material. • The plasterboard has favorable mechanical strength and cost/environmental benefits. • The plasterboard has the potential to be a new alternative wall material. Solid waste phosphogypsum (PG) generated during phosphoric acid production was used as the sole raw material to prepare a new paper-free and fiber-free plasterboard. Dehydrated PG was granulated with water, press-formed and hydrated with intermittent pressing into paper-free and fiber-free plasterboards with bending strength of 14.7 MPa. The semi-hydrate gypsum is hydrated into dense and interlocking dihydrate gypsum crystals, thereby achieving a high mechanical strength. Due to the free of paper, fiber and additive, the plasterboard is effective to recycle PG and has potential to be a new-type wall material with favorable fire resistance, cost-effectiveness and environmental friendliness. [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]

• Evolution of linear attenuation coefficient (LAC) regarding carbonation may vary via different CT. • X-ray energy level used for CT scan can reverse the LAC relationship between calcium carbonate and calcium hydroxide. • Hygral equilibrium and polymorphs of carbonation product can also affect the LAC of carbonated areas. A discussion on a recently published article authored by Kim et al. [Effect of carbonation on cement paste microstructure characterized by micro-computed tomography. Constr. Build. Mater. 263 (2020) 120079] is presented. [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]

• It is feasible to use paper-based asphalt felt (RPAF) waste in asphalt mixtures. • The effects of RPAF on the rheological property of asphalt-binders is a function of temperature. • Asphalt mixtures with RPAF exhibited better moisture stability and anti-rutting property. • The fatigue life of the asphalt mixtures increased with the addition of RPAF. Paper-based asphalt felt, which is typically used as a waterproofing material, is one of the most problematic solid wastes in terms of disposal and environmental contamination. The laboratory work presented in this paper aims to propose a strategy for utilizing the reclaimed paper-based asphalt felt (RPAF) waste in hot-mix asphalt (HMA) pavements as a means to mitigate the RPAF disposal problem. A series of laboratory tests, including viscosity, modulus, rutting, and cracking, were conducted to investigate the effects of RPAF additives on the engineering performance of asphalt-binder and HMA mixes. The corresponding test results showed that the addition of RPAF improves the viscosity and high-temperature performance of asphalt-binders. However, RPAF modified asphalt-binder exhibited inferior storage stability than the virgin asphalt-binder due to the difference in density between the asphalt-binder and RPAF components. Additionally, the effect of RPAF on the rheological characteristics of the asphalt-binder exhibited high sensitivity to temperature. The differences in complex modulus and phase angle of the asphalt-binder with RPAF additives were generally more significant at elevated temperatures. Similarly, RPAF modified HMA mixes outperformed the control HMA mix in terms of resistance to moisture damage, rutting, and cracking, respectively. Overall, the laboratory test results indicated that it is feasible to utilize RPAF waste as an asphalt-binder modifier to enhance the engineering properties/performance of the asphalt-binder and HMA mix whilst simultaneously addressing the environmental issues of RPAF waste disposal. [ABSTRACT FROM AUTHOR]

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

Lignosulfonates are water-soluble anionic polyelectrolyte polymers produced during industrial paper manufacturing. This study investigated concrete produced using lignosulfonates with various chemical contents at different concentrations. Therefore, concrete mixtures were produced using Ca-lignosulfonate (LSc), Na-lignosulfonate (LSn), Mg-lignosulfonate (LSm), and K-lignosulfonate (LSk) at concentrations of 0.4% and 0.8% by weight in the cement. Samples containing cements with different C 3 A, C 3 A + C 4 AF, and Na 2 O + K 2 O contents and variable fineness were tested to determine a compatible combination of cement and lignosulfonates. Results revealed that LSc was suitable for use in cements with greater C 3 A content and fineness and 0.8% was an appropriate usage concentration. [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]

3D printing technology, as a rapid prototyping method, can accurately reconstruct the internal structural characteristics of samples, making it highly promising for rock engineering applications. However, current 3D printing materials used to reconstruct rocks suffer from low strength and high ductility, which is inconsistent with the high strength and brittleness of natural rocks. This paper explores the use of silane coupling agents KH550 (γ-aminopropyl triethoxysilane) and KH570 (γ-methacryloxypropyl trimethoxysilane) to modify nano SiO 2 powder. Through sample preparation and uniaxial compression tests, the mechanical properties and failure characteristics of the modified nano SiO 2 powder were analyzed. The results indicate that, using the preparation method with a mass ratio of E-44 epoxy resin, KH550 modified nano SiO 2 powder, and 593 curing agent at 80:40:26, the samples achieved an uniaxial compressive strength of up to 30.55 MPa without enhanced brittle post-processing. The failure characteristics exhibited significant axial tensile damage. Additionally, combining CT scanning technology demonstrated that the structural and mechanical properties of the samples can be effectively reproduced. Therefore, the 3D printing materials discussed in this paper provide a viable reference for accurately reconstructing high-strength and high-brittleness rock masses. • New printing material can model the high strength and brittleness of rocks. • Different silane coupling agents on nano SiO 2 -modified E-44 epoxy resin. • Mechanical properties and failure modes of samples with varying mass ratio. [ABSTRACT FROM AUTHOR]

This paper considered the effects of coarse aggregates and proposed a continuous bond-slip theoretical model between Ultra-high performance concrete with coarse aggregates (UHPC-CA) and rebar. Due to the impact of coarse aggregate on crack development and fiber distribution, an improved fiber-matrix discrete model was proposed, combining the thick-walled cylinder solution and the fictitious crack model to analyze the bond-slip behavior across the uncracked, partial cracking, and complete cracking stages. This paper investigated the effects of rebar diameter, coarse aggregate particle size, coarse aggregate content, bond length, and cover thickness on the ultimate bond strength. The results showed that rebar diameter had minimal impact on ultimate bond strength, while bond stress loss increased by 35.0 % as the coarse aggregate content increased from 10 % to 40 %. A total of 76 sets of pull-out test data were collected and compared, indicating that the predicted ultimate bond stress and peak slip of the proposed model had average ratios of 1.000 and 1.022 to the experimental values, with coefficients of variation of 0.124 and 0.284, respectively, and the error was generally within 20 %. Furthermore, the relative error between the predicted and test results remained within 15 %, while the bond-slip relationships based on different softening curves exhibited a relative error not exceeding 5.0 %. The proposed model accurately predicted the bond-slip relationship between UHPC-CA and rebar. • Proposed the improved fiber-matrix discrete model for fiber bond stress considering the influence of coarse aggregate characteristics. • Proposed the continuous model of bond-slip in UHPC-CA considering the effect of coarse aggregate. • Analyzed the main parameters affecting the proposed model between UHPC-CA and rebar. • Collected UHPC-CA pull-out test results confirmed the ultimate bond stress, peak slip and bond-slip relationship. [ABSTRACT FROM AUTHOR]