Search

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]

• 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]

• 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]

• 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]

• 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]

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]

• 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]

• 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]

[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]

• 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]

• 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]

• 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]

• 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]

• Statistical models were developed for proportioning wastepaper sludge ash CLSMs. • The impacts on the properties of CLSMs of the mix design parameters were evaluated. • Parameters of the mix design are designed for satisfactory CLSM properties. • Robust mixtures of CLSM that meet DOT requirements are stated. • The proposed models are beneficial techniques for the design of practical applications for CLSMs. This study aims to create robust controlled low-strength material (CLSM) mixes of wastepaper sludge ash (WSA) binders and recycled fine aggregates (RFAs). A factorial design was carried out to mathematically model the effect of three main mix design parameters on the plastic and hardened properties of wastepaper sludge ash CLSM (WSA-CLSM) mixtures. The criteria were the ratio of water to cementitious materials (w/cm), the proportion of WSA replacement content, and the total cementitious material (cm) content. Flowability, bleeding, segregation, initial stiffening time, densities, water absorption, and unconfined compressive strength were the derived statistical models' responses. With the intention of extracting the statistical models, twenty mixes were prepared, and ten mixes were used to validate the precision of the produced models. The models are valid for mixtures of 2.53 to 2.73 w/cm, 50 to 100% of WSA (by total cm content) and 160 to 200 kg/m3 of total cm content. The regression methods were synthesised and analysed by classifying the key factors and their correlations to measure their properties in terms of the impacts of w/cm, WSA% and total cm content. Three optimum WSA-CLSM mixtures with significant positive desirability were formulated and tested using the established models. Robust WSA-CLSMs that meet the Department of Transportations (DOTs) specifications for CLSM backfill material classifications may be developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Coupled effects of rest time and temperature on self-healing were evaluated. • Two healing indices were introduced, based on stiffness and fatigue endurance gain. • Time-dependent artefacts were quantified and removed from the two healing indices. • A new model was proposed to describe the healing performance of bituminous binders. • The effects of both rest time and temperature were combined into self-healing charts. The experimental work described in this paper investigated the coupled effects of rest time and rest temperature on the self-healing potential of bituminous binders. A set of neat and polymer-modified materials were subjected to self-healing tests that included two oscillatory shear loading phases separated by a single rest period. Multiple testing conditions were analyzed by combining various rest times and rest temperatures. Self-healing was quantitatively assessed by introducing two healing indices, based on the magnitude of stiffness and fatigue endurance gain, in which time-dependent artefacts were properly quantified and removed. Experimental results were found to be consistent with the kinetics of self-healing phenomena and underscored the importance of considering rest time coupled with rest temperature for a reliable evaluation of true self-healing properties. A new model was proposed to describe the self-healing performance of bituminous binders and self-healing charts were constructed from generalized logistic functions incorporating the effects of both rest time and temperature. [ABSTRACT FROM AUTHOR]

• Mechanical and environmental study performed to identify optimum waste content. • Novel method developed for processing municipal waste cardboard within concrete. • Low inclusion of cardboard can enhance tensile strength of hybrid concrete. • Polypropylene fibers are effective in bridging disruption of cardboard to cement. • LCA impact assessment show favourable comparisons to benchmark concretes. This paper presents an experimental study and findings on the requalification of waste cardboard as a fine-aggregate replacement in the development of waste-based concrete. The design of eco-efficient and green-star concrete has become a significant focus, driven by the impact of industrial and municipal waste on both the environment and the global economy. The study aimed to utilise materials such as waste cardboard, polypropylene, and ground-granulated blast furnace slag as partial replacements for Ordinary Portland Cement and fine natural aggregate. It specifically focused on developing techniques for processing recycled cardboard into an aggregate suitable for this study. Six concrete batches were cast with incremental dosages of finely processed recycled cardboard and a fixed dosage of recycled polypropylene macro-fibres. An experimental program was conducted to determine fresh and mechanical properties at 7 and 28 days. The results were used to identify an optimal dosage level of waste cardboard suitable for commercial use. Additionally, a small-scale life-cycle assessment was performed to evaluate the environmental impact of the hybrid concrete mix. The processed cardboard exhibited desirable rheological and mechanical properties, making it a suitable fine-aggregate replacement. The addition of recycled polypropylene fibres enhanced flexural and tensile strength, establishing the blend as a suitable concrete mixture design for real-world applications. Furthermore, the life-cycle assessment highlighted the effectiveness of the mixture designs when compared to benchmark concrete mixtures. [ABSTRACT FROM AUTHOR]

• A method for batch calculation of aggregate shape parameters was proposed based DIP. • The numerical model of mortar fluidity test was successfully established by DEM. • The increase in flake particle content leads to greater elongation of machined sand. • High flaky particle content can lead to poor flowability of mortar. • There is a correlation between the aggregate shape parameters and the fluidity. This paper combined digital image processing (DIP) and discrete element method (DEM) to investigate the relationship between the particle characteristics of manufactured sand and the flow ability of mortar, and clarified the key characteristics parameters of particle shape influencing the flow ability of mortar. A method for batch calculation of shape characteristic parameters (elongation n e , angularity index n a and fullness ratio n f) of aggregates based on DIP was proposed. The fluidity tests and corresponding simulations of mortar at different water-cement ratios were carried out respectively, and the results showed that the errors of simulated fluidity (f m) were around 7%. The simulation results demonstrated that the f m decreased with increasing content of large-size aggregates in the mortar. The augment of both n e and n a reduced the flowability of mortar. The magnitude of rolling/sliding friction coefficients of aggregates are the important parameters that determine the flowability of mortar. [ABSTRACT FROM AUTHOR]

• Lignin as partial replacement of bitumen for producing bio-asphalt materials. • Raw material and production process of lignin significantly affect the performances of bio-materials. • Laboratory multi-scale approach and real-scale applications of bio-materials are discussed. • Life-cycle assessment and economic analysis are addressed. • Lignin-based asphalt materials represents a promising technical and environmentally friendly solution. Nowadays, one of the most interests of modern society is to replace increasingly larger quantities of petroleum-derived products, which is a non-renewable source progressively depleting, so promoting both environmental and economic benefits. In this context, the practice to employ renewable sources to replace part of the bituminous materials is an effective approach in pavement engineering. Among different biomasses which are recognized as possible sources mixable with bitumen, lignin can represent a valid material. Lignin is a natural resource commonly deriving from the by-product of the production of pulp and paper industry. It is the second most common biopolymer on Earth and represents a potentially attractive alternative as partial substitute of bitumen. However, in order to understand the environmental and technical feasibility of the application of lignin in bituminous pavement applications, a multi-scale approach must be adopted. For this purpose, the paper aims at providing an overview of the use of lignin as renewable source in bituminous binders and mixtures, by investigating chemical, rheological and mechanical properties of lignin modified asphalt materials. Moreover, based on the available literature, field application experiences and Life Cycle Assessment (LCA) analysis are also discussed. [ABSTRACT FROM AUTHOR]

In recent years, with the improvement of construction safety requirements in deep well mining, the backfill mining method has been widely used. However, the strength of paste filling acquired in quarry often surpasses the design strength determined in laboratory settings. In view of the problems that indoor conditions cannot restore deep mining environment, and the mechanism of coupling effect under multiple fields is unclear. This paper has carried out relevant research work through theoretical analysis and indoor experiments. First of all, after completing the preparatory experiments, this paper analyzed the strength difference of backfill under different curing stress and drainage conditions, and studies the influence of different curing conditions on the strength. Secondly, MPS-6 and 5TE sensors were used to monitor the electrical conductivity, pore water pressure, porosity and other parameters of backfill during the stress-drainage curing process, and changes of parameters during curing process were analyzed. Finally, the relationship among relevant parameters and strength properties of paste backfill was analyzed, as to clarify the influence mechanism of stress-drainage curing conditions on the strength formation for paste backfill. Research shows that both stress-undrained and stress-drained conditions can effectively increase the strength of backfill. Under stress-drainage conditions, the internal porosity of backfill will decrease, and the pore water pressure of backfill will first increase slightly and then continue to decrease. Under this condition, the electrical conductivity of backfill will first increase and then continue to decrease. The entire research has important positive significance for reducing mining costs, optimizing mining processes, and developing mining technology. • The instrument is a self-developed equipment, which can monitor changes of backfill in real time. • The test blocks were cured under different stress and drainage conditions. • Binarize the scanned image of samples, and then use ImageJ to analyze the processed image. • Combined with two sensors, the relationship between microscopic parameters and strength can be explored. [ABSTRACT FROM AUTHOR]

To study the differences in material performance between HRB400E steel and conventional strength steel, this paper performed monotonic and cyclic loading tests on HRB400E and Q355B steels under a series of loading protocols. Additionally, the self-designed fixtures were used to achieve large strain rate loading. The ductility, monotonic behavior and hysteretic characteristics of HRB400E and Q355B steels were assessed, along with the energy dissipation capacity evaluated through the energy dissipation coefficients. The cyclic skeleton curves of both steels were fitted using the Ramberg-Osgood model, with further investigation into the influence of kinematic hardening parameters on hysteretic curves. The combined hardening parameters of the Voce-Chaboche model were calibrated based on the experimental results, and the hysteretic curves were simulated under different loading protocols via ANSYS. The analysis results reveal that the energy dissipation coefficients of HRB400E steel are larger than that of Q355B steel, yet smaller than those of Q460D, LYP100, LY100, LY160, and LY225 steels. Both HRB400E and Q355B steels demonstrate significantly improved material strength under cyclic loading. Excellent agreement between simulated and experimental curves is achieved when using four pairs of kinematic hardening parameters. Additionally, the hysteretic performance of HRB400E and Q355B steels under different cyclic loading protocols can be precisely simulated by employing calibrated combined hardening parameters. Through this paper, the cyclic behavior and constitutive relations of HRB400E steel are comprehensively understood, which provides a reliable theoretical basis for engineering design and structural analysis. Furthermore, this research provides a scientific basis for material applications of HRB400E steel. • HRB400E steel and conventional strength steel are compared in material performance. • Monotonic and cyclic loading tests are conducted. • Ductility, monotonic property, and hysteretic performance of HRB400E and Q355B steels are assessed. • Self-designed fixtures are utilized to achieve large strain rate loading. • The hysteretic property of the HRB400E steel can be accurately simulated. [ABSTRACT FROM AUTHOR]

Reinforced concrete is a commonly used material for constructing basements in low-rise buildings or residential houses in Canada, and as the use of cross-laminated timber (CLT) advances, the door to think of an alternative basement material to offset greenhouse gas emissions associated with reinforced concrete is open. However, the evaluation of CLT durability in below-grade environments, specifically concerning moisture and mould development, remains an unexplored field in research. Hence, this paper aims to analyze CLT's moisture response and mould growth risk in below-grade environments using field and laboratory experiments. A laboratory experiment was carried out to test a waterproofing membrane solution selected to compose the wall assembly in the field experiment. A large-scale experimental CLT basement was built at a cohesive soil site in Edmonton, Canada. The field experiment involved monitoring the relative humidity, temperature, and soil volumetric water content of the CLT panels, which measure 3 m by 6 m in plan and 2 m deep. Data was collected for an extended period from June 2022 to July 2023. The VVT model, developed by Hukka and Viitanen (1999) and updated by Viitanen et al., 2011 to estimate the mould growth level, was used to predict the risk of mould growth. The laboratory experiment showed that the waterproofing membrane is suitable for protection against moisture in a still-water setup. Field experiment results suggested that the primary moisture source was below the basement floor when the floor was finished inadequately. The moisture content of CLT walls was significantly increased by floor flooding and decreased by heating the basement interior. The acceptable mould index of three was surpassed during periods of abundant water below the basement floor due to flood events, showing that the CLT panels were at risk of mould growth development. • CLT use inbasements is in research stage. This paper contains insights for developing future research on this subject. • CLT in basement construction requires robust envelope with waterproofing membranes that perform well below grade. • Elevated moisture levels could pose structural and biological risks to the CLT basement and its occupants. • CLT basement walls take time to dry, and during this period, the walls may be exposed to risky levels of mould growth. [ABSTRACT FROM AUTHOR]

3D printing technology revolutionizes construction by creating custom building components with increased efficiency and reduced waste. This paper reviews advancements in the 3D printing of cementitious materials, focusing on integrating mineral additives (MAs) like metakaolin, micro-silica, slag, and fly ash to address environmental and economic challenges linked with high-Portland cement content in 3D concrete printing (3DCP). MAs enhance the pumpability, printability, and buildability of 3DCP while reducing its environmental impact. The review emphasizes optimizing cement mixtures, including alkali-activated materials, to enhance sustainability and performance. It discusses the mixture design's importance, balancing mechanical properties and environmental impacts, and examines MAs' influence on rheological properties, mechanical performance, and 3DCP durability, including layer bond strength. The paper also discusses global 3D printing technology adoption in construction and challenges in additive manufacturing implementation. By analyzing printing parameters, mixture proportions, and materials' effects on long-term performance, this review highlights 3D printing's potential for economically viable and eco-friendly structural elements. It aims to guide future advancements in 3D printable cementitious materials, meeting modern construction demands while addressing traditional concrete production's environmental challenges. • Using recycled mineral additives reduces 3D-concrete printing's environmental impact. • Optimizing printing parameters strengthens layer bonds in 3D-concrete printing. • Recycled materials promote sustainability and innovation in 3D-concrete printing. [ABSTRACT FROM AUTHOR]

Grouting is one of the most commonly used methods to control water inrush disasters in fractured rock mass. At present, most of the research on the diffusion process of fracture grouting is carried out on the hypothesize that the groundwater was completely displaced by the slurry, which is lack of sufficient theoretical basis. Therefore, a one-dimensional visual fracture grouting experimental system was developed and a new characterization method of slurry concentration based on the image gray level was proposed in this paper in order to characterize the variation law of slurry-water mixing region during the grouting process. Results show that there exists slurry-water mixing region at the frontal surface of the diffusion slurry in the grouting process in fractured rock mass. The slurry-water mixing region can be characterized by the gray level of the images captured by cameras. The relationship of water to cement ratio of slurry (w/c) and image gray level of slurry (G) conforms to linear function, which can be expressed by G = 19.17 w/c when w/c is between 0.8 and 10. In addition, slurry concentration decreased linearly along the diffusion flow path in the slurry-water mixing region. The size of slurry-water mixing region is positively related to grouting flow rate, the mass ratio of water to cement (w/c) and fracture aperture when the grouting flow rate is between 0.6 L/min to 2.4 L/min, w/c is between 0.8 and 1.6 and fracture aperture is between 1 mm to 5 mm. Furthermore, the ratio of slurry-water mixing region size to hypothetical diffusion radius (RSR) was proposed to characterize development degree of slurry-water mixing region. The stable value of RSR was between 0.04 and 0.24 under the experimental conditions in this paper. The index of RSR can be used to provide theoretical basis for the simplification of the interface between slurry and water. The distribution rules of the slurry-water mixing region can be applied to predict the diffusion range more accurately and perfect the grouting theory. • Image gray level method was introduced to characterize the variation of slurry-water mixing region during grouting process. • Experimental system for simulation of one-dimensional visual fracture grouting was presented. • The ratio of slurry-water mixing region size to hypothetical diffusion radius was developed. [ABSTRACT FROM AUTHOR]

This paper investigates the behavior of reinforced concrete (RC) arch beams with shear weaknesses strengthened with fiber-reinforced polymer (FRP) composites, using two different methods: the externally bonded reinforcement (EBR) and grooving method (GM) in the form of externally bonded reinforcement on grooves (EBROG) method. Additionally, two different patterns of shear strengthening including two-sided and U-shaped were utilized. Nine arch beam specimens were tested, each having a square cross-section of 150 mm and a span length of 947 mm. Among these, two specimens were strengthened using the EBR method, while six specimens were strengthened using the EBROG method. The paper explores the impact of the strengthening method and pattern on the load-carrying capacity, failure mode, energy dissipation, and strain distribution of the specimens. The results indicate that the EBROG method significantly increased the load-carrying capacity of the arch beams compared to the EBR method in both patterns. The results also show that the U-shaped pattern was more effective than the two-sided pattern in increasing the load-carrying capacity of the specimens. The specimen with intermittent U-shaped FRP demonstrated 34.8% and 47.3% higher load-carrying capacity than the non-strengthened specimen when using the EBR and EBROG methods, respectively. The paper also introduces an analytical approach to estimating internal forces, such as flexural moment, axial force, and shear force, along the arch beam. The comparison between the experimental and theoretical results confirms the accuracy of the analytical approach. • The behavior of RC arch beam with shear weakness was investigated. • EBR and EBROG methods were adopted for strengthening of the arch beam. • PIV method was utilized to obtain the strain distribution, validate the displacements, etc. • An analytical procedure was conducted to validate the experimental results and investigate the performance of the strengthening methods. [ABSTRACT FROM AUTHOR]

This paper studies the effect of high temperatures (20℃, 200℃, 400℃, and 600℃) and stress ratios ( σ 2 / σ 3 ) (0.15, 0.3, 0.45, and 0.60) on biaxial compressive strength and strain development patterns of high-strength geopolymer concrete (HGPC). Experimental observations indicate that HGPC exhibits laminar damage similar to ordinary Portland concrete (OPC) before and after exposure to high temperatures, under biaxial compression. Unlike OPC, damage in HGPC initially passes through coarse aggregates at room temperature but shifts predominantly to the aggregate-mortar interface at 600℃. The biaxial compressive strength envelope of HGPC expands with rising temperatures. The increased multiple of biaxial compressive strength ( σ 3 / f m ) for HGPC at room temperature rises and then falls with increasing stress ratios, peaking at a stress ratio of 0.45 and surpassing the values for OPC and high-strength concrete (HSC). Before high temperature, the modulus of elasticity of HGPC is higher than that of OPC and decreases with increasing temperature, decreasing by about 45–60% for every 200°C increase, and the reduction is greater than that of OPC. The existing failure criterion is not suitable for HGPC after high temperature, this paper develops a new biaxial compression failure criterion for HGPC before and after high temperature based on Kupfer's criterion, taking into account the effect of temperature. The proposed failure criterion calculation results are well in agreement with the experimental data. A damage constitutive model for HGPC considering the effect of temperature and lateral pressure is also proposed, combining the Weibull distribution model for the ascending branch and a modified empirical model for the descending branch. This combined model effectively predicts the stress-strain relationship of HGPC under various temperature conditions. • The axial behavior of HGPC is tested at different temperatures and lateral pressures. • A failure criterion for biaxial compression of HGPC taking into account the effect of temperature is proposed. • A damage constitutive model of HGPC considering the effect of temperature and lateral pressure is established. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of bond in post-tensioning strands in the presence of grout injection defects. In particular, the paper describes a campaign of experimental pull-out tests with a single 7-wire steel strand in the centre of a galvanised sheet metal duct with no grouting defects and with 25% and 50% defects, i.e. voids in the cross-section area of the grout. The grouted length is short in order to obtain a local bond–slip relationship. This relationship has an initial branch followed by a jump descent and a subsequent growing branch in the form of a sawtooth. The experimental data are used to define a specific bond–slip relationship that takes into account the presence of defects. The results show that the obtained bond–slip law is very different from those proposed in the literature for the case of ribbed steel bars. Furthermore, the defects cause a decrease in bond stresses and a flattening of the shape of bond–slip curves. • Bond of post-tensioning strands is studied. • Experimental pull-out tests are performed. • Effect of grout injection defects is investigated experimentally. • A bond-slip relationship for post-tensioning strands with defects is proposed. [ABSTRACT FROM AUTHOR]

Engineered Cementitious Composites (ECC) utilize the bridging effect of high toughness fibers to improve the brittle failure of concrete materials, achieve the effective control of cracks in cementitious materials, and significantly improve the deformation capacity. In view of the multi-stage crack-blocking effect of different fibers incorporated in ECC materials, 91 ECC specimens of steel-polypropylene hybrid fiber by mixing steel fiber (SF) and polypropylene fiber (PPF) into cement-base are made in this paper. The specimens are tested in compression, tensile, bending and damping properties, respectively, which is of great significance to study the response of ECC structures under the earthquake action. The effects of the volume content of SF and PPF on the mechanical properties of ECC are studied in this paper. The results show that the cube specimen has better ductility than the prismatic specimen under monotonic compression, and there is no obvious brittle failure. With the increase of the volume content of SF to PPF, the compressive strength and elastic modulus of hybrid fiber ECC gradually increase, while the corresponding strain and axial compressive toughness gradually decrease; the tensile strength and tensile modulus increase, while the bending strength and damping ratio decrease. According to the test results, constitutive models of monotonic and repeated loading of hybrid fiber ECC suitable for finite element (FE) analysis are proposed. This investigation provides a theoretical basis and an experimental reference for further study of steel-polypropylene hybrid fiber ECC. • Steel fiber and polypropylene fiber are mixed as hybrid fiber of ECC. • The mechanical properties of ECC are investigate. • Volume content of steel-polypropylene hybrid fiber has influence on concrete material. • The hybrid fiber ECC cube has better ductility than that of prismatic. • Constitutive models of hybrid fiber ECC are suitable for finite element analysis. [ABSTRACT FROM AUTHOR]

This paper focuses on the experimental and analytical behavior assessment of novel sandwich panels fabricated with recycled glass-fiber/polyester resin (GFRP) core and PVC face sheets. The originality of the present work is based on sustainable development and waste recovery to design lightweight and eco-friendly structures. In this respect, the panels cores were fabricated using fully recycling of fiber-glass waste issued form the boats building. Accordingly, a set of sandwich panels with various core configuration and fibers orientation were manufactured and tested up to failure under three-point bending to characterize flexural and shear properties. In addition, validated analytical equations were advocated to assess the bearing capacity of the studied panels. The obtained results in terms of mechanical, thermal and physical features are emphasized, discussed and confronted with a good agreement to literature ones. A principal component analysis was conducted to optimize the effect of the geometrical parameters on the panel failure mechanisms. As main outcomes, the work can provide environmental and economic solutions for the design of sandwich structures. • Lightweight and eco-friendly sandwich structures-based GFRP waste core were designed • Validated analytical equations were advocated to assess the bearing capacity of the studied panels under bending • A principal component analysis was conducted to optimize the geometric parameters of the panels • The paper results provide environmental and economic solutions for the design of sandwich structures [ABSTRACT FROM AUTHOR]

The maintenance design for existing asphalt pavements, characterized by their typical structure and material composition, falls short of meeting the diverse requirements of pavements. There is an urgent need for a more rational design approach that can achieve accurate pavement design while also reducing construction costs. This paper focuses on selected conventional road surface structures and conducts an analysis of how pavement structure and materials impact fatigue life and construction expenses. It employs Python to perform three-dimensional finite element road modeling, analysis, and data extraction at specific locations, using normalized fatigue equation to calculate pavement fatigue life. The optimization variables selected are the modulus E and thickness h, with pavement maintenance cost serving as the optimization target function. The particle swarm optimization algorithm is employed for optimizing these variables. A comparative analysis is carried out for five improved optimization algorithms, optimizing combinations of inertia weight, learning factors, particle speed, number of particles, and iteration times. The results reveal that the enhanced optimization algorithms significantly improve iteration trends, featuring velocity limitations and natural selection mechanisms. Between 0 and 20 iterations, all algorithms search for the optimal solution over a wider interval with greater fluctuations. Between 20 and 30 iterations, each algorithm gradually converges towards its solution, stabilizing in the later stages. Based on optimization speed and actual engineering cost benchmarks, the NDPSO algorithm is selected, resulting in a 52.8% reduction in actual engineering costs. Adjustments to the particle count and iteration number of the NDPSO algorithm are made based on computational cost and optimization accuracy, thus choosing 20 particles and 50 iterations as the recommended parameter combination. By combining automated finite element modeling, analysis, and particle swarm optimization, this paper offers a novel and effective automated design reference for extending the lifespan of asphalt pavement structures. • An improved particle swarm optimization model for fatigue life with consideration of the modulus E and thickness h. • The automation of finite element modeling, calculation and data extraction is completed by using further development. • Normalized fatigue equation is used to calculate pavement fatigue life. • A novel and effective automated design reference for extending the lifespan of asphalt pavement structures is proposed. [ABSTRACT FROM AUTHOR]

This paper presents a thorough investigation into utilizing hybrid fibers, comprising both steel and polymeric fibers, to enhance the compressive and tensile behaviors of ultra-high-performance concrete (UHPC). Flowability tests revealed potential usability challenges with polymeric fibers, emphasizing the necessity for careful consideration. Compressive strength results demonstrated that hybridizing straight steel fibers with short hooked steel fibers results in performance similar to that of reduced steel fiber content. Elastic modulus trends correspond with those of the compressive strength, and unexpectedly positive effects on the ultimate strain capacity under compression are observed with long polyvinyl alcohol fibers. Tensile behavior analysis highlights the superiority of both short and long hooked steel fibers, with the latter contributing the highest tensile strength. However, the use of polymeric fibers significantly decreases the tensile strength owing to insufficient dispersion and low tensile strength. Scanning electron microscopy images of UHPC with polymeric fibers reveal debonding and surface damage, with potential advantages observed for polypropylene fibers through methods such as surface moisture coating. In conclusion, this paper provides insights into optimizing fiber content and types for UHPC, emphasizing a balance between reduced fiber content and maintained performance. The proposed hybrid reinforcement approach, particularly with short hooked fibers, is promising for practical usability and cost-effectiveness in construction applications. • Addition of hybrid fibers, particularly polymeric fibers, results in a decrease in flowability. • Hybridizing with hooked fibers decreases the fiber content by 0.5 % given similar strength levels. • Long PVA fiber is effective in increasing elastic modulus of UHPC due to limited deformation. • Hybrid use of straight and hooked steel fibers exhibits improved tensile performance of UHPC. • Introduction of PVA and PP fibers causes a decrease in the tensile strength of UHPC. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the variation rule of coarse aggregate and pore structure of shotcrete by adding MWCNTs. In the paper, X-ray computed tomography scans are used to study the coarse aggregate distribution and pore structure of the preparation of shotcrete, high-temperature curing shotcrete and shotcrete with MWCNTs. The distribution pattern of coarse aggregate and pore of shotcrete is obtained. The results show that: the coarse aggregate loss of shotcrete is serious within 30 mm from the wall and the coarse aggregate increases significantly in 30–70 mm. The addition of 0.03% MWCNTs increased the coarse aggregate of shotcrete by 36.63% and the volume of coarse aggregate by 25.64%. The largest increase is in coarse aggregates of 5–7 mm. This show that MWCNTs can improve mortar adhesion and reduce aggregate rebound. The number of shotcrete pores decreases with the increase of pore diameter. The proportion of small pores is up to 85%, the proportion of large pores is only 2%, but the volume of large pores reaches 87%. The addition of 0.03% MWCNTs can reduce the number of small pores in the shotcrete and reduce the mean pore diameter, resulting in a decrease in the porosity of the shotcrete. When the curing temperature is 80℃, the porosity of shotcrete increases, and the pores decrease due to interconnection. The pores around the coarse aggregate account for over 70% of the total porosity, with pores larger than 1 mm accounting for 75%. This paper has a good reference value for the development of shotcrete and the selection of coarse aggregate in the actual working conditions. • The coarse aggregate distribution and pore structure characteristics of shotcrete were revealed. • The influence of MWCNTs on the rebound of shotcrete coarse aggregate was analyzed. • The relationship between pore distribution of shotcrete and coarse aggregate distribution is discussed. [ABSTRACT FROM AUTHOR]

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]

Utilizing nano-SiO 2 (NS) to reinforce the old mortar and the weak interfacial transition zone (ITZ) in recycled coarse aggregate (RCA) is a productive approach to enhance the quality of RCA. Throughout this paper, RCA was immersed in NS solutions with different concentrations (2, 5, 10 and 30 wt%). Subsequently, a systematic evaluation of the crushing index and water absorption of the treated NS modified recycled coarse aggregate (SRCA) was conducted. In addition, the calcium hydroxide (CH) content of RCA before and after modification was analyzed by Thermogravimetric and Differential Thermal Analysis (TG-DTA) curves. This study finds that the performance of SRCA modified with 2% concentration achieves comparable modification effects to other concentrations. Additionally, this paper delves into the impact of NS powder on the slump characteristics and compressive strength of concrete. Considering the above research and economic costs, this study adopts 2% concentration of NS for RCA modification and further investigates the stress-strain relationship of NS modified recycled aggregate concrete (SRAC) with various SRCA replacement ratios. Moreover, this paper establishes mesoscopic models of SRAC for various replacement rates and proposes constitutive models corresponding to these rates. The results indicate that when the SRCA replacement rate is within 60%, the stress-strain curve shape of SRAC closely resembles that of natural aggregate concrete (NAC); when the replacement rate exceeds 60%, the descending segment of the SRAC stress-strain curve becomes more precipitous, showing a higher tendency towards fragility in the concrete. ● Nano-SiO 2 can be used to improve the properties of recycled coarse aggregates. ● NS powder affects the slump and compressive strength of recycled concrete. ● As the concentration of NS solution increases, the compressive strength of concrete increases. ● Mesoscopic models of modified recycled concrete were established and constitutive models were proposed. [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]

When a slurry shield tunnel traverses through extensive deposits of silty clay stratum, a considerable amount of high-viscosity waste slurry with elevated particle content is inevitably generated. Failure to promptly address this waste slurry could have a severe impact on project progress and the surrounding environment. To address the challenge of rapid dewatering for high-moisture and high clay-content waste slurry, this paper introduces an efficient waste slurry dewatering technique: magnetic flocculation dewatering technology. Additionally, the paper explores avenues for the resource utilization of waste slurry containing magnetic particles Through conducting flocculation settling experiments, a comparative analysis was carried out on the dewatering effects of traditional flocculation and magnetic flocculation technologies. The paper discusses the dewatering mechanism of magnetic flocculation and determines the optimal process conditions for treating waste slurry utilizing magnetic flocculation. The results indicate: (1) The flocculation and dewatering process of waste slurry can be divided into two stages: a rapid flocculation settling stage and a slow consolidation stage, with the rapid flocculation settling stage playing a dominant role. (2) Under magnetic flocculation, the time required for the rapid flocculation settling stage is only 1/3 of that in traditional flocculation, and the slurry dewatering rate is 1.4 times higher than traditional flocculation. (3) The optimal sequence for adding material under magnetic flocculation is to add magnetic powder first and then the flocculant. The optimum dosage of magnetic powder is 1.0 g/L, and the most suitable magnetic field intensity is 92.0 mT. (4) The magnetically flocculated sludge obtained after magnetic flocculation treatment can be utilized for the production of construction bricks that comply with standard specifications. The research findings of this paper provide a basis and guidance for the efficient reduction and resource utilization of waste slurry. • A novel efficient technique for dewatering of waste sludge, known as magnetic flocculation dewatering technology, is introduced. • Comparative analysis between traditional flocculation and magnetic flocculation techniques is conducted to confirm the superior dewatering efficiency of magnetic flocculation. • The mechanism of magnetic flocculation technology in the dewatering process of waste sludge is elucidated, leading to the identification of optimal operational conditions for waste sludge treatment under magnetic flocculation. • A pathway for the resource utilization of waste sludge is proposed, with the feasibility of using waste sludge for the production of construction bricks without firing being validated. [ABSTRACT FROM AUTHOR]

This study proposed a procedure to optimize the mixture proportion of geopolymer using machine learning (ML) and multi-objective optimization (MOO) model, which enhances the compressive strength and minimizes the carbon emission and costs. The experiment was preliminary carried out to analyze the workability, compressive strength, microstructure, and pore characteristics of fly ash/slag-based geopolymer. The results showed that the higher replacement ratio of slag established positive effects on the hardening as well as porosity improvement due to the coexistence of C-S-H and NASH-type binders, especially for a ratio was no more than 60%. Considering the performance of geopolymers is often influenced by multiple factors such as material composition and curing conditions, which could not be solved by traditional methods. A database containing 836 samples was established to analyze the prediction performance of 7 ML models by using Bayesian optimization. The GPR model has good generalization ability, with R 2 being 0.99 (0.99) on the testing set (training set). Furthermore, the reliability of the ML models was evaluated by the tests conducted in this paper. The feature importance analysis utilizing SHAP method indicates that Age, HM, and SS are key parameters influencing the compressive strength of geopolymer. The proposed MOO model can effectively evaluate the trade-offs between compressive strength, carbon emission, and costs, and all Pareto solutions for bi-objective and three-objective provided the optimal mixture schemes. On this basis, the design procedure proposed in this paper can give the scheme of geopolymer materials with different requirements (given mixture scheme and given design strength). [Display omitted] • Working mechanism of different matrix on geopolymer are revealed. • SHAP method can explain the physical mechanism of parameter on the output variable. • Reliability of the intelligent prediction model is validated by experiment. • MOO model can evaluate the relationship between CS, CO 2 and costs of geopolymer. • Procedure of geopolymer mixture schemes with different design strength are proposed. [ABSTRACT FROM AUTHOR]

This paper comprehensively reviews present research on the potential for repurposing primary categories of waste plastics. These include Polyethylene Terephthalate (PETE), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Low-Density Polyethylene (LDPE), Polypropylene (PP), Polystyrene (PS), and other variants such as Acrylonitrile Butadiene Styrene (ABS), Ethylene Vinyl Acetate (EVA), Polycarbonate (PC), and Polyurethane (PU). The focus is on their use in the construction of bituminous mixes via the dry process method. This method incorporates plastic waste into bituminous mixes by modifying the mixture or replacing aggregates. This practice has consistently demonstrated improvements in pavement performance, including increased stiffness, resistance to rutting, and fatigue. When bituminous mixtures are modified with the mixture modifying approach using low melting point plastics such as LDPE, HDPE, and LLDPE, a significant reduction in OBC is observed. Furthermore, the mixture modification approach has demonstrated higher resistance to moisture damage, rutting, and fatigue damage than the aggregate replacement approach. The potential benefits of using plastics in the bituminous pavement are substantial. This includes a reduction in the amount of waste sent to landfills, a decrease in reliance on finite natural resources, and the expansion of options for constructing bituminous pavements. Economic analyses have shown that using waste plastics can reduce pavement construction costs by 10%, with a minimal probability of leaching. Despite a multifold increase in the emission of greenhouse gases, an overall reduction in environmental impact was observed from the life cycle assessment study. However, the use of PVC and dark-colored plastics is not recommended. Field studies conducted on roads constructed with waste plastic-modified bituminous pavements showed notable improvements. Most of these pavements exhibited higher Pavement Condition Index (PCI) values and lower International Roughness Index (IRI) values than conventional pavements. These findings underscore the superior riding quality and reduced deterioration associated with waste plastic incorporation. Moreover, in-plant production processes, plants require minimal modifications, as existing equipment used for feeding fibers is well-suited for adding plastics into the mixture. In conclusion, further research is essential to fully understand the impact of different types of plastics on pavement performance and to evaluate this process's potential environmental and economic implications. This paper seeks to bridge the gap in the literature by reviewing and discussing the performance of such mixes and constructed pavements in laboratory and field situations. ● The impact of different plastics on mechanical performance of bituminous mix has been reviewed. ● Plastics at OPC improves bituminous mixture's mechanical performance. ● Long term field performance studies have been reviewed. ● Pavements containing waste plastics shows better riding quality and less deterioration. ● Future studies should more focus on environmental assessment. [ABSTRACT FROM AUTHOR]

Over the past year, ChatGPT's initial applications across diverse fields have progressed amid debates on its ethical implications and inherent biases. This paper investigates the comprehension level of ChatGPT 4.0 regarding cementitious composites and initiates preliminary research into its application in cementitious composites，including ordinary Portland cement (OPC) concrete, Engineered Cementitious Composite (ECC), and Ultra-High-Performance Concrete (UHPC). Initially, the study designed forty-five progressively challenging questions to examine the readability and accuracy of ChatGPT's responses related to cementitious composites. Building on this, the research explored the feasibility of utilizing ChatGPT for the identification and analysis of ECC cracks, the design of mix proportions for cementitious composites, and the real-time analysis of carbon emissions. The results demonstrate ChatGPT 4.0's proficiency in acquiring foundational knowledge of cementitious composites, a capability verified through interactive human-computer modalities for analysing crack quantity and width, formulating preliminary material compositions, and providing instantaneous feedback on carbon emissions. However, the study also uncovers ChatGPT 4.0's limitations in understanding the complex design mathematics and mechanics underlying cementitious composites, as well as its inadequate ability to synthesise and integrate interdisciplinary knowledge, occasionally leading to arbitrary and forced responses. These findings underscore the need for further enhancements in algorithmic sophistication and database comprehensiveness. The paper concludes by projecting the future applicability of ChatGPT in the cementitious composites sector, highlighting its initial contributions while delineating avenues for subsequent research and development. • The understanding of ChatGPT on cementitious composites was investigated. • The preliminary application study of ChatGPT 4.0 was conducted. • The future application prospects of ChatGPT were anticipated. [ABSTRACT FROM AUTHOR]

All-Bamboo Aggregate Concrete (BAC) is a type of cement concrete material where all coarse aggregates are made of bamboo aggregate, a plant material that requires necessary measures to avoid or slow down its degradation in alkaline and natural environments. This paper enhances the durability of BAC materials through the treatment of bamboo aggregate with ACQ-polyacrylate (AP method). Initially, the study explores the impact of polyacrylate dilution concentration on the compressive strength and coating thickness of BAC, and based on a reasonable modification process, conducts freeze-thaw cycles, salt solution immersion, accelerated wet-dry aging, and long-term natural environment tests to assess the durability of BAC materials. The results show that a polyacrylate solution with a dilution ratio of 1:5 can form a coating thickness of 23.8μm, performing better in various durability evaluations. After 25 freeze-thaw cycles, the BAC material's loss rate of compressive strength is lower than that of Ordinary Concrete (OC). Compared with OC, BAC materials are more susceptible to salt damage after salt solution immersion. The compressive strength loss rate under 180 days of natural environment exposure is comparable to that in 10 cycles of accelerated wet-dry aging, 28 days of salt solution immersion, and 10–15 freeze-thaw cycle tests, recommending the use of freeze-thaw cycle tests for evaluating the durability of BAC materials from an experimental efficiency perspective. By exploring the durability of BAC materials, this paper provides an innovative solution in the field of construction materials, promoting the transition of the construction industry towards sustainable development. It emphasizes the feasibility and effectiveness of improving the performance of bamboo-based materials through surface treatment technology, offering a valid reference for developing more environmentally friendly and high-performance new materials in the future. • BAC materials show lower durability than traditional concrete. • Polyacrylate solution can enhance BAC durability. • Polyacrylate solution can enhance BAC durability. • Future research should optimize polyacrylate modification. [ABSTRACT FROM AUTHOR]

Building precise machine learning and deep learning models has traditionally required a combination of mathematical skills and hands-on experience to meticulously adjust hyperparameters that significantly impact the learning process. As datasets continue to expand across various engineering domains, researchers increasingly turn to machine learning methods to uncover hidden insights that may elude classic regression techniques. This surge in adoption raises concerns about the adequacy of resultant meta-models and the interpretation of findings. In response to these challenges, automated machine learning (AutoML) emerges as a promising solution, aiming to construct machine learning models with minimal intervention or guidance from human experts. This paper benchmarks AutoML solutions by providing an overview of their principles and applying them to predict the most important mechanical properties of different concrete datasets, i.e., compressive strength. Nine datasets from various concrete types, sample sizes, and features are utilized, with a detailed discussion on the benchmark dataset from high-performance concrete, applying best practices to the other eight datasets. For each case, the importance of hyperparameter tuning is discussed, alongside the ensemble and stacking models. Tree-based models are employed for each dataset to develop SHAP plots, interpret results, and understand the contribution of each component in the mix design to the overall strength of the concrete. This paper further explores three unique aspects of benchmarking AutoML in material science: (1) "reliability" by contrasting the benchmark dataset's error metric with literature collected over the past 20 years, (2) "uncertainty" by quantifying the variability in the mean and standard deviation of the error metric from different datasets and its correlation with the sample-to-feature ratio, and (3) "dilemma" by discussing the shortcomings of AutoML in specific concrete datasets. • The first comprehensive application of AutoML is presented in the concrete regression model. • Nine different concrete datasets are compared in terms of compressive strength. • AutoML's reliability, and dilemmas are evaluated in predicting concrete strength. • A benchmark problem is discussed to quantify the AutoML uncertainty in material science. • Explainable machine learning is used to identify the key contributing factors in f' c. [ABSTRACT FROM AUTHOR]

This paper not only studies the influence of fiber content on the mechanical properties of steel fiber ultra-high performance concrete (SFRUHPC), but also conducts high-speed impact tests and simulations on high-volume fiber targets with varying thicknesses to evaluate the damage characteristics of the SFRUHPC targets, such as residual velocity and penetration depth of the projectile. The results indicate that compared with ordinary concrete and low fiber content targets, the flexural strength and compressive strength of the target incorporated with 7% steel fiber reach the maximum values of 87.9 MPa and 362.9 MPa, respectively, which are significantly improved. On the other hand, the 7% steel fiber reinforced target demonstrates excellent anti-penetration performance which is evidenced by a 51.9% lower residual velocity compared to ordinary concrete targets in thin target tests, as well as a 37.4% reduction in penetration depth in thick target tests. Additionally, the rebound phenomenon of the projectile is observed during the tests. Furthermore, the three-dimensional mesoscopic numerical model established exhibits a good correlation with the experimental results. Finally, the model adopted in this paper can better predict the residual velocity and depth of penetration of the projectile. • The anti-penetration performance of three types of targets incorporating high content steel fibers were evaluated. • The high content steel fibers attribute to the better penetration resistance. • The phenomenon of projectile rebound is observed in a thick target with a steel fiber content of 7%. • The established three-dimensional mesoscopic numerical model aligns well with the experimental data. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the microstructure of high-viscosity modified asphalt binder (HVA) containing high-content polymers and its effect on fatigue performance, as well as the applicability of different analytical methods and failure criteria of linear amplitude sweep (LAS) test to HVA. In this paper, two types of HVAs with different polymer contents, a commercial HVA, a conventional polymer-modified asphalt binder, and a base asphalt binder were first prepared or selected. Fluorescence microscopy tests, time sweep tests, and LAS fatigue tests were then performed on these binders. Finally, the fatigue properties of the different binders were analyzed in depth using different analytical methods and failure criteria. The results show that the polymers in HVA crosslink with each other to form a strong cross-linking structure, and the phase inversion of the polymers renders them into a continuous phase, which significantly improves the fatigue damage resistance of the HVA; moreover, the evolutions of stress with shear strain for the fatigue process of HVAs is related to the polymer network. Besides, the two-dimensional damage characteristic curve (DCC) cannot accurately reflect the evolution of the fatigue performance of HVA, and this paper suggests the use of a three-dimensional DCC curve with strain information. Furthermore, the 35% reduction in C 0 in the dissipative energy method is not a suitable failure criterion, a more accurate fatigue performance ranking can be obtained by using the yield stress as the failure criterion. Although the fatigue resistance of HVA after yield stress is theoretically considered using the pseudo-strain energy approach, HVA does not show a peak of stored pseudo-strain energy even when the strain is increased to 60% in the LAS test. Therefore, the maximum strain value (30%) in the standard LAS test is not sufficient in characterizing high-polymer HVAs because there is not enough fatigue accumulation of HVAs in this range, consequently, the maximum shear strain parameter in the LAS experiment needs to be reconsidered. • Polymer morphology and its crosslinking networks in HVA with high-content polymers were analyzed. • The fatigue properties of HVAs based on LAS test and different analytical methods are compared. • The fatigue crack length and its evolution of HVA are characterized. • The deficiencies of the LAS test to evaluate the fatigue resistance of HVA and suggestions for modifications are presented. [ABSTRACT FROM AUTHOR]

This review paper presents a comparative evaluation of polymer, bacterial-based, alkali-activated, and geopolymer binders in regard to their production methods, mechanical properties, their environmental/life cycle assessment (LCA), and durability when exposed to deteriorating cycles (such as sulfates, acids, and high temperatures). The significance of this study is to compare the results of over 400 journal papers, which present an in-depth analysis of fresh and hardened state properties of various binders that are advocated in the literature. Historically, Portland cement is generally considered a binder that plays a major role in any cementitious composites because of its high availability, and relatively inexpensive cost. Despite its significant benefits, it is known that the manufacturing process of Portland cement is energy and carbon intensive, and the resulted material often has shortcomings when exposed to deteriorating causes such as sulfates, acids, and high temperatures. However, recent movement toward net-zero as well as ultra-high-performance practices has increased the need for a more sustainable and durable binding system. Based on the result of this paper, each binder presents specific advantages when compared to Portland cement for specific applications that can be a better choice for their ultra-high capabilities and ecological properties. This includes the significantly better performance of alkali-activated binders (specifically geopolymers), under high temperatures, or very rapid strength gain of polymer (e.g., epoxy, polyester, and vinyl ester) binders, making them great alternatives to Portland cement, for rapid repair and rehabilitation purposes. Similarly, bacterial concrete also have certain capabilities such as long term durability and the potential for a continued self-repair or self-healing. In terms of environmental impacts, however, polymer binders are heavily depedant on their source of energy (e.g., petroleum vs. bio-based resins) while alkali-activated concretes and geopolymers have activators' large contributions to overall LCA impact categories. For bacterial binders, the used urea and nutrition can play a key role in their LCA results. Finally, based on the highlighted capabilities of each binder, recommendations on performance-based or hybrid design methods and specifications for an optimized system are also provided. Novel areas in polymer, bacterial-based, alkali-activated, and geopolymer binders are also included. • A comparative analysis of various binding systems are provided. • Mechanical, Durability, and Ecological Properties vary significantly across binders. • Concentration, surface area, temp., and catalysts play key role in each binder. • Unique advantages and shortcomings of each binder is discussed. [ABSTRACT FROM AUTHOR]

Shape memory alloy (SMA) is an innovative intelligent material, capable of restoring its shape before deformation upon reaching the critical activation temperature. This property promotes its promising applications in civil engineering. This paper proposes a novel reinforcement method and aims to investigate the reinforcing effect of iron-based shape memory alloy (Fe-SMA) plates on prestressed concrete (PC) beams through four-point bending tests on one reference beam without reinforcement and three Fe-SMA reinforced beams, as well as with three beams reinforced by carbon fiber-reinforced polymer (CFRP). The results show that Fe-SMA can effectively reduce concrete cracks, and improve stiffness and characteristic loads of beams without negative effects. Under the same loading conditions, new cracks of Fe-SMA reinforced beams were relatively fewer than those of CFRP reinforced beams. Besides, Fe-SMA exhibited superior performance when utilizing the same cross-sectional reinforcement material to enhance the bending capacity of beam, and proved more advantageous for improving stiffness and characteristic loads of beam under the identical initial tensile force. Furthermore, the reinforcing effectiveness of Fe-SMA positively correlates with the cross-sectional area (thickness) and recovery stress (pre-stretch level and activation temperature) of Fe-SMA. Increasing the thickness of Fe-SMA plates by 100%, while maintaining other parameters constant, resulted in a 33% increase in cracking load. Similarly, elevating the recovery stress from 314 MPa to 340 MPa led to a 12.5% rise in cracking load. This paper investigates the reinforcement effect of Fe-SMA plates on PC beams, and provides a reference for the application of Fe-SMA in PC beam reinforcement, laying a foundation for promoting the utilization of Fe-SMA in civil engineering. • A novel reinforcement system to strengthen PC beams employing Fe-SMA plates was proposed. • The effect of Fe-SMA plates on PC beams through four-point bending tests was compared with CFRP tendons. • Fe-SMA was more effective than CFRP in enhancing the bending capacity of PC beams. • The reinforcing effectiveness of Fe-SMA positively correlates with cross-sectional area and recovery stress. [ABSTRACT FROM AUTHOR]

Surface (microscale) roughness of coarse aggregates influence the cement suspension' viscosity and the interfacial bonding strength of concrete, but its characterization method is not consolidated and still a research challenge. 3D scanner determines accurately the shape, volume, but it is incapable of describing the roughness at microscale. Roughness at microscale (surface index – cm2/cm2) can be measured accurately using interferometry, but it cannot describe shape and volume of the particles. Once the volume of aggregate particles may vary 200% and it seems crucial to establish the (micro)roughness per volume (cm2/cm3) to better understand the effects in the properties of cementitious materials. This paper presents a method of obtaining volumetric surface area of coarse aggregates at micrometric scale by joining (cm2/cm3) both techniques. Three types of aggregates were assessed: gneiss, low-grade meta-carbonate (dolomite) and quartzite (gravel), with one hundred particles in the size range of 4.75 mm to 37.5 mm. For coarse aggregates, the larger the particles, the more of their surface area will be influenced by (mesoscale) shape and less by surface (microscale) roughness. However, the smaller the particles, SI index will differ considerably. The surface area determined by the method proposed in this paper provides a good correlation with the methylene blue method. • New method to determine volumetric surface area (VSA) of aggregates. • Light white interferometry and 3D scanning methods combined. • Shape and roughness (multiscale) morphological descriptors discussed. [ABSTRACT FROM AUTHOR]

In this paper, a thermo-mechanical sequential coupling mesoscopic simulation method was established and verified, which considered the interaction between steel tube and meso-components of concrete due to the difference in thermal parameters, as well as the low-temperature effect on mechanical parameters. On the basis of heat conduction analysis, the damage evolution and failure mechanism of CFST column under axial compression were subsequently revealed, and the effects of low temperature (20, −30, −60 and −80 °C), cross-section size (160, 320, 480 and 640 mm), width-thickness ratio (27, 36, 53 and 107) and cross-section shape (square and circular) on axial compression performance and the corresponding size effect of CFST columns were quantitatively analysed. Research results show that the low-temperature action can enhance the nominal peak strength and residual strength of CFST column, but weaken the ductility. As the cross-section size increases from 160 to 640 mm, all the nominal peak strength, nominal residual strength and peak strain of circular CFST column decrease with the maximum reductions of 16.2, 28.7 and 16.9%, respectively. Besides, the low-temperature action can enhance the size effect on nominal peak strength of CFST column with the maximum increase of 68.8%. Whether at ambient or low temperature, the size effect on nominal peak strength of square column is stronger than that of circular one. The size effect behaviour on axial compressive peak strength at various temperatures can be also well described by the previous proposed prediction formula. The research results of this paper can provide reference for the engineering application of large-sized CFST columns in the extreme low-temperature environment. • The thermo-mechanical sequential coupling method at low temperature was developed. • The effect of low temperature, width-thickness ratio, cross-section size and cross-section shape were considered. • The mechanical properties and corresponding size effect of CFST columns at low temperature were quantitatively analyzed. [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]

To improve the fatigue behaviour of the concrete, this paper explored a potential innovative method: the joint addition of expansive agents (EA) and glass fibres (GF). It was envisaged that the addition of EA reduced additional defects caused by the addition of GF to the concrete, while the compressive prestress caused by EA enhanced the bonding between GF and the concrete, thereby improving the fatigue behaviour of the concrete. The test results indicated that the synergistic effect of EA and GF effectively improved the static bending strength, fatigue life, and deformation performance of the concrete. The synergistic effect of EA and GF on the fatigue life of the concrete was revealed qualitatively and quantitatively. The synergistic effect was further demonstrated from perspectives of the fatigue deformation and fatigue stiffness. Furthermore, P - S - N curves of EA and GF reinforced concrete were established, and the fatigue ultimate strength and conditional fatigue ultimate strength were provided as a design basis. This paper recommended adding an appropriate amount of EA to glass fibre reinforced concrete to achieve better concrete properties. • Joint addition of EA and Gf was a potential method for improving concrete. • Bending tests were used to elucidate fatigue bending performance of concrete. • Synergistic effect of EA and GF on fatigue performance of concrete was reveal. • Using two-paramater Weibull distribution, P - S - N curves were established. [ABSTRACT FROM AUTHOR]

Freeze-thaw modification is a novel method that improves recycled aggregates by utilizing the expansion of pore water during phase transitions. However, there is still a lack of theoretical analysis regarding each component in recycled aggregates during freeze-thaw. In this paper, we introduce the parameter of pore radius to transform the traditional 2D phase diagram into a 3D phase diagram of pore water. This transformation makes the phase transition conditions of pore water more clear to understand. It is then combined with the pore size distribution of each component in recycled aggregate to calculate the ice content and freezing pressure. To achieve a more intuitive evaluation of frost susceptibility, this paper establishes a frost vulnerability index (FVI). Based on the FVI curves of different rocks, their frost resistance is categorized into three levels. Finally, according to the FVI of recycled aggregates with diverse material properties, some recommendations are provided for the engineering application of freeze-thaw modification. • By introducing the pore radius, the 2D phase diagram of water is transformed into a 3D diagram. • FVI has been established to assess the susceptibility of different materials to freeze-thaw damage. • The commen natural rocks are classified into three levels based on their frost resistance. • The necessity of thermo-drying is verified through analysis. • Theoretical analysis is conducted on the saturation level required and during the vacuum saturation. [ABSTRACT FROM AUTHOR]