Cement-based Materials Research Articles

Functionalized cements incorporated with nanocomposite photocatalysts for self-cleaning applications

The constantly escalating pollution on the surface of cement-based materials affects architectural aesthetics and residents′ health, necessitating frequent cleaning and maintenance, which contradicts the concept of sustainable development. This study aimed to develop a novel photocatalytic cement material to enhance the self-cleaning capabilities of cement-based materials, thereby extending their service life and reducing maintenance costs. To achieve this, carbon quantum dots (CDs) and g-C3N4 (CN) nanocomposite photocatalysts (CDs@CN) were synthesized and integrated into white cement to prepare photocatalytic cements. The materials were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy. Photocatalytic performance was evaluated by the degradation of Rhodamine B (RhB) under xenon (Xe) lamp, Vis light and UV light. The CDs@CN nanocomposite displayed superior photocatalytic activity, particularly under Xe lamp irradiation, achieving over 95 % degradation of RhB within 1 h. Even under Vis and UV light, the photocatalytic cement retains robust self-cleaning capabilities, achieving pollutant degradation rates of 81 % and 63 %, respectively, within 1 h. This performance exceeded that of pristine CN and control samples, demonstrating effective light absorption and charge separation. The optimal photocatalyst concentration in cement was identified as 0.1∼5.0 wt%, balancing performance and dispersion. The developed CDs@CN-based photocatalytic cement material offers a sustainable solution for self-cleaning and environmental purification. This study provides insights into the design of functional cementitious materials and contributes to the sustainable development of the construction industry.

Improving the Performance of Mortar under Carbonization Curing by Adjusting the Composition of Ternary Binders

As the most widely used building material, cement has attracted the attention of scholars because of its large carbon emission. To alleviate the problems of carbon emission and limited resource use caused by cement production, this study focuses on the performance of mortar after carbonization curing by regulating the composition of ternary binders. Testing involved mechanical parameters, carbon shrinkage, water absorption, hydration product, microstructure, adsorption of carbon dioxide, calcium carbonate content, and carbonization degree of mortar, as well as comparisons with the effect of calcium carbide slag and sintered red mud. We carried out several studies which demonstrated that carbonization curing and adjusting the content of calcium carbide slag and sintered red mud were beneficial to improve the mechanical properties, peak load displacement, slope, elastic energy, plastic energy, carbon shrinkage, carbon dioxide adsorption, calcium carbonate content, and carbonization degree of mortar, while the addition of calcium carbide slag and sintered red mud increased the water absorption of mortar, and the greater the dosage, the greater the water absorption. Meanwhile, adding 25%–50% calcium carbide slag and sintered red mud still had negative effects on the mechanical properties of mortar. But carbonation curing and the addition of calcium carbide slag and sintered red mud could promote the hydration reaction and consume calcium hydroxide formed by hydration to form calcium carbonate. When the dosage was 50%, the carbon dioxide adsorption capacity, calcium carbonate content, and carbonization degree of calcium carbide slag mortar were higher than those of sintered red mud mortar, which increased by 29.56%, 102.73%, and 28.84%, respectively. By comparison, calcium carbide slag and sintered red mud still showed superior carbon sequestration capacity, which was higher than fly ash and Bayer red mud. From the experiment, we came to realize that adjusting the composition of cementitious materials could realize the carbon sequestration of cement-based materials and promote the road toward low-carbon sustainable development of cement.

Low-carbon cementitious composite incorporated with biochar and recycled fines suitable for 3D printing applications: hydration, shrinkage and early-age performance

In recent years, the construction industry has witnessed significant advancements in concrete technology, particularly with the integration of 3D printing in cement-based materials. While this innovation offers promising opportunities for the sector, the high binder and fine particle content of 3D printing mixes presents a substantial environmental challenge due to their considerable carbon footprint. To mitigate this impact, strategies often involve substituting portions of the binder or aggregate with waste materials. This article presents a comparative analysis of two promising approaches to reducing the carbon footprint of 3D printing concrete mixes by partially replacing cement with biochar and recycled fines. The study examines the effects of these materials on the rheological properties and early-age hydration processes of the 3D printing mix. A reference mix (REF) was established, followed by the development of eight additional mixes, with four incorporating biochar and four incorporating recycled fines, each replacing 1.25%, 2.5%, 5%, and 10% of the cement volume. The findings indicate that recycled fines have a neutral effect on the spread flow diameter of the mixture but increase initial deformations in printed elements. Conversely, biochar, due to its water absorption capacity, reduces fluidity, enhancing buildability by enabling faster printing with minimal initial deformation. Additionally, replacing up to 2.5 vol.% of cement with either material accelerates the normalized heat flow, contributing to a quicker gain in mechanical properties. However, biochar increases shrinkage deformations within the first 12 hours, while recycled fines mitigate them. Importantly, replacing up to 10 vol.% of cement with these materials does not significantly compromise early compressive strength.

Gas permeability of partially saturated cement-based materials considering water sensitivity

Gas permeability is a crucial factor influencing the durability of cement-based materials, which are usually in a partially saturated state. This study examines the impact of the water-to-cement (w/c) ratio, water saturation and water sensitivity on the gas permeability of cement-based materials using Nuclear Magnetic Resonance (NMR) and Mercury Intrusion Porosimetry (MIP). The results indicate that the gas permeability of cement-based materials is strongly related to their porosity and pore size distribution. Relative gas permeability is directly influenced by water saturation and the initial state of the materials, with a noticeable hysteresis effect observed. Furthermore, the water sensitivity of cement-based materials results in no evident, but a slight decrease in gas permeability during water saturation.

Development and characterisation of myristic acid-paraffin wax, silica fume and zinc oxide cementitious composites for thermal control in buildings

This study focuses on the development of a cement-based phase change material (CBPCM) to improve thermal performance in construction applications. The CBPCM was synthesised by blending 90 wt% of myristic acid with 10 wt% of paraffin wax, absorbed into 10 wt% of silica fume to prevent leakage. Additionally, 5 wt% of zinc oxide was added to improve thermal conductivity. A leakage test conducted with 10 wt% of SF exhibited no signs of leakage during thermal cycling. Scanning electron microscopy (SEM) established the uniform dispersion of the nano-enhanced phase change material (NEPCM) within the cement. Fourier transform infrared spectroscopy (FTIR) analysis revealed no chemical structure changes after 100 thermal cycles. Thermogravimetric analysis (TGA) confirmed thermal stability in the temperature range of 74.8–236.64 °C with a mass loss of 6.3 wt%. The material demonstrated minimal variation in phase change temperatures and latent heats after 100 cycles. The latent heat of the CBPCM was 1.09 J/g during melting and 1.887 J/g during solidification. Incorporating NEPCM into the cement increased the thermal conductivity of the cement matrix to 0.559 W/m K. These findings underline the potential of the CBPCM for energy-efficient construction, offering enhanced thermal storage, stability, and conductivity.

Effects of interlayer-modified layered double hydroxides with organic corrosion inhibiting ions on the properties of cement-based materials and reinforcement corrosion in chloride environment

Developing novel, environmentally friendly, and efficient corrosion inhibitors is of great significance for improving the durability of marine concrete against chloride ion erosion. This paper aims to explore the potential of layered double hydroxides (LDHs) as nanocontainers, incorporating organic corrosion inhibitors between LDHs layers to synergistically enhance their effectiveness. In this study, Mg/Al-pAB-LDH was synthesized through the interlayer modification of LDHs with an organic corrosion inhibitor, p-aminobenzoic acid (pAB), employing a calcination-rehydration method. Chloride ion (Cl−) adsorption behavior was quantitatively and qualitatively analyzed and the effect on mortar properties was investigated. The corrosion resistance of steel bars in the mortar was assessed under chloride salt simulated concrete pore solution (SCPs) and chloride salt wet-dry cycles via electrochemical tests and microscopic characterization of Mg/Al-pAB-LDH. The results demonstrate that Mg/Al-pAB-LDH efficiently captures Cl− and releases corrosion-inhibiting ions pAB, with the adsorption process conforming to pseudo-second-order kinetics and Langmuir adsorption isotherm. Mg/Al-pAB-LDH enhances the pore structure of mortar, effectively improving mechanical properties and resistance to chloride ion penetration, with the optimal effect observed at a 4 % addition rate. Mg/Al-pAB-LDH demonstrates outstanding corrosion resistance to steel bars in both SCPs and mortar. In SCPs, it serves as a corrosion inhibitor by adsorbing Cl− and releasing pAB, whereas in mortar, it functions as a corrosion inhibitor by enhancing the physical barrier effect of mortar, adsorbing Cl−, and releasing pAB. This study demonstrates the promising potential of utilizing Mg/Al-pAB-LDH as a novel corrosion inhibitor to mitigate the corrosion of steel bars in marine concrete.

A randomized controlled clinical trial of the performance of three bioactive endodontic cements in primary molar teeth diagnosed with reversible pulpitis: 1-year follow-up study

ObjectivesThe objective of this clinical trial was to evaluate and compare the clinical and radiographic successes of three bioactive endodontic cements (BEC) including novel portland cement-based material releasing fluoride, resin-modified silicate glass cement, and pure tricalcium silicate-based cement—in the treatment of primary molars diagnosed with reversible pulpitis via indirect pulp capping. MethodsEighty-six (86) participants with previously untreated first and second primary molars were included in this study. The teeth were randomly allocated into three groups: pure tricalcium silicate-based cement, resin-modified silicate glass cement, and novel portland cement-based material releasing fluoride. Cavities were capped with the assigned cement after caries excavation using standard protocols. The teeth that underwent treatment were restored using glass ionomer cement and composite resin. Clinical and radiographic evaluations were performed at 1, 6, and 12 months. The data were analyzed using Pearson chi-square, Kruskal–Wallis H and Z test (P = 0.05). ResultsThe success rate was 88 % (n = 25) in the pure tricalcium silicate-based cement group, 88.5 % (n = 26) in the resin-modified silicate glass cement group, and 100 % (n = 25) in the novel portland cement-based material releasing fluoride group. The differences at the 1st, 6th, and 12th month follow-up visits were not statistically significant among the groups (P > 0.05). No difference was found between the integrity of the resin composite restorations overlying pure tricalcium silicate-based cement, resin-modified silicate glass cement, and novel portland cement-based material releasing fluoride according to the USPHS criteria. ConclusionsNovel portland cement-based material releasing fluoride can be considered an alternative for preserving the tooth, as it showed a high success rate in treating primary molars diagnosed with reversible pulpitis via indirect pulp capping. Clinical significanceNovel Portland cement-based material releasing fluoride could be beneficial in the treatment of primary molars diagnosed with reversible pulpitis via indirect pulp capping.

Electrical resistivity of cement-based materials through ion conduction mechanisms for enhancing resilient infrastructures

Cement-based materials (CBM) in humid environments, influenced by their inherent defects and the presence of pore solution, exhibit poor electrical insulation performance. Low electrical resistivity of cement-based materials poses a threat to the safety of resilient infrastructures, shortens the lifespan of materials, and increases the costs of maintenance and repair. In this work, we first elucidate two primary mechanisms for enhancing electrical resistivity: (1) inhibition of ion electromigration and (2) disruption of conduction paths. We then systematically summarize and discuss 16 potential methods for improving their electrical resistivity based on these mechanisms. It is indicated that among these 16 methods, early carbonation curing, the addition of high-activity mineral admixtures, and surface hydrophobic modification are particularly effective approaches. The combination of two or more methods can simultaneously exert their functions, thus maximizing the overall effectiveness. Future work is outlined with the aim of meeting the growing demand for cement-based materials with high electrical resistivity in the construction of resilient infrastructures.

A machine learning model for predicting the mechanical strength of cement-based materials filled with waste rubber modified by PVA

As demand for sustainable building materials rises, the use of waste rubber in civil engineering is gaining attention. This study proposes a method to modify waste rubber using polyvinyl alcohol (PVA) to enhance its material properties and expand its applications. A dataset was created focusing on the mechanical strength of cementitious materials incorporating PVA-modified waste rubber, and multiple machine learning methods were used to develop regression prediction models, particularly evaluating the support vector regression (SVR) model. Results show that the SVR model outperforms others, achieving mean squared errors of 1.21 and 0.33, and mean absolute errors of 2.06 and 0.15. Analysis indicates a negative correlation between waste rubber content and the water-to-cohesive ratio (w/c) with strength indexes, while a positive correlation exists between curing age and PVA. Notably, waste rubber content significantly affects strength. The mechanical strength of cementitious materials was notably enhanced by PVA-modified waste rubber, likely due to PVA's dispersion and bridging effects. This study presents a novel approach to sustainably recycle waste rubber, highlighting its potential in construction materials.

Impact of silica fume on the long-term stability of cement-based materials with low water-to-binder ratio under different curing conditions

Silica fume is commonly employed in cement-based materials with low w/b. However, the properties evolution of low water-to-binder cement-based materials with silica fume and the impact of silica fume on the performance of paste are still unclear. In this study, the water absorption and desorption, linear deformation, and mechanical properties of low w/b pastes with varying silica fume contents cured under both lime-saturated water and drying conditions were conducted. Furthermore, the impact mechanism of silica fume on the performance of the paste was explored through measurements and analyses of the hydration process, hydration products, and crack characterization. The results show that the flexural and compressive strengths of the paste with silica fume cured under varying conditions exhibit fluctuations. This is attributed to the fact that, while silica fume diminishes expansion and expansion cracking under lime-saturated water curing, it also enhances shrinkage and shrinkage cracks. Under drying conditions, the strength fluctuations can be attributed to the refinement of the structure of the material by the addition of silica fume, coupled with increased shrinkage and cracking.

Effect of nano-Ti-Li-Al hydrotalcite-like on the hydration and hardening properties of sulfoaluminate cement-based materials

The use of sulfoaluminate cement-based materials (SCBMs) in grout reinforcement projects is common, and they also perform well in road repair and other facilities. To obtain high workability and permeability, a large water-to-cement ratio is generally used, which reduces the early mechanical properties of SCBMs. The early mechanical properties of cement-based materials can be improved by adding nanomaterials. The cement hydration product monosulfate (AFm) belongs to the hydrotalcite-like family, which is also called layered double hydroxide (LDHs). At present, there is no literature on the influence of nano-Ti-Li-Al layered double hydroxide materials (TiLiAl-LDHs) on SCBMs. In this study, two types of nano -TiLiAl-LDHs with different Ti/Li/Al molar ratios (Ti1Li3Al4-LDHs and Ti2Li3Al4-LDHs) were synthesized. Nano-Ti1Li3Al4-LDHs promoted the hydration of the slurry and improved the early mechanical properties of SCBMs to a greater extent than nano-Ti2Li3Al4-LDHs. However, the cause of this phenomenon remains unclear. Nano-TiLiAl-LDHs act as nucleation sites for ettringite (AFt) and AFm, both of which are cement hydration products. Among them, Ti1Li3Al4-LDHs preferentially provided nucleation sites for AFt, whereas Ti2Li3Al4-LDHs preferentially provided nucleation sites for AFm. Ti1Li3Al4-LDHs and Ti2Li3Al4-LDHs can release titanium, lithium, and carbonate ions in the SCBMs paste, and Ti1Li3Al4-LDHs release more lithium ions (up to 50 mg/L) while Ti2Li3Al4-LDHs release more titanium ions (up to 100 mg/L). Li+ can consume AlO2− and OH− in the slurry and form amorphous lithium aluminum compounds. Although Li+ inhibits the formation of AFt products, it promotes the hydration of anhydrous calcium sulfoaluminate (ye’elimite). Ti4+ reacts with OH− to form a complex that inhibits the formation of AFt, thus reducing the hydration of SCBMs. CO32− promotes the formation of calcium carbonate and indirectly promotes the dissolution of ye’elimite and gypsum. The nucleation effect and release of titanium, lithium, and carbonate ions acted synergistically to influence the hydration and hardening processes of SCBMs. Compared with Ti2Li3Al4-LDHs, Ti1Li3Al4-LDHs has a greater ability to enhance the hydration and mechanical properties of the slurry owing to its strong nucleation and release of higher concentrations of lithium ions and lower concentrations of titanium ions.

Cement-based and alkali-activated controlled low-strength materials made from cup lump rubber for use as road materials

This research explores the use of cup lump rubber (CLR), an agricultural by-product, as a component in controlled low-strength material (CLSM) for pavement applications in road construction. Two distinct CLSM mixtures were developed: one based on cement and the other on alkali activation. The study evaluated the workability, mechanical properties, and microstructures of both CLSM formulations. Key fresh properties, including slump flow, setting time, and bleeding, were analysed to assess their impact on the self-compaction process. Mechanical characteristics such as unconfined compressive strength, resilient modulus, and wave velocities were also measured. Some CLSM mixtures, both cement-based and alkali-activated, were found to meet the requirements for soil cement bases and subbases. Notably, the resilient modulus values showed significant improvement after 28 days, with certain mixtures achieving subbase-quality gravel standards. The study concludes by recommending the use of both cement-based and alkali-activated CLSMs in pavement design, highlighting their potential to enhance the field of pavement engineering.

Self-healing of cracks in cement-based materials through bio-mineralization of low air-dependency microorganisms

Microbial self-healing technology for concrete is attracting widespread attention due to its environmentally friendly, non-toxic, and sustainable attributes. Currently, microbial agents utilized in concrete exhibit a high dependence on atmospheric conditions, relying on atmospheric oxygen to activate or capture carbon dioxide from the air for the generation of carbonate ions. This paper introduces an innovative low-dependency microbial restorative aimed at augmenting the self-healing capability of concrete by nearly doubling the available carbonate ions and providing 80 % of them internally, especially targeting deep cracks. A pioneering approach was employed by combining microorganisms that rapidly produce carbon dioxide with those that expedite carbon dioxide hydration. Microbial functional components were meticulously pelletized to create core-shell structure restorative particles, featuring an outer protective layer constructed with low-alkali cement. This study investigates the mechanism through simulation and experimentation, including substrate conversion, carbon dioxide transformation, and the generation and accumulation of carbonate ions and calcium ions. Essentially, this research not only presents a path towards reduced atmospheric dependence but also provides valuable insights for comprehending the mechanism behind microbial self-healing concrete.

Investigation of functionalized graphene oxide incorporated superabsorbent polymers for enhanced durability, hydration, microstructure and mechanical strength of modified concrete

ABSTRACT This study focuses on enhancing cementitious materials by incorporating silanized graphene oxide (SGO) and superabsorbent polymers (SAPs), aiming to improve their mechanical and durability properties. The primary goal is to evaluate the effects of SGO/SAP composites on the hydration, absorption, shrinkage, and overall performance of concrete. The composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) to understand their microstructure. Mechanical and durability tests revealed that adding SGO/SAP composites significantly increased the mechanical strength and water absorption capabilities of the concrete. The compressive strength, split tensile strength, and flexural strength of the SGO/SAP-modified concrete were measured at 57 MPa, 4.90 MPa, and 8.25 MPa, respectively. Shrinkage tests demonstrated the composite hydrogel’s excellent water-holding capacity at 0.3 wt.% SGO/SAP, facilitating internal curing in concrete structures. FE-SEM analysis indicated a reduction in microcracks due to the presence of SGO/SAP. The improvements are attributed to the synergistic effects of SGO and SAP, which enhance water retention, dispersion, and interfacial bonding within the cementitious matrix. The microstructural studies confirmed the exceptional stability of the SGO/SAP-modified mix, emphasizing its potential as an additive to improve concrete properties. This research underscores the significant potential of SGO and SAP in advancing the performance of cement-based materials, highlighting their applicability in infrastructure development and construction for creating more durable and high-performing concrete structures.

Insights on the mechanical properties and failure mechanisms of calcium silicate hydrates based on deep-learning potential molecular dynamics

The molecular-scale mechanical properties of calcium silicate hydrates are crucial to the macro performance of cementitious materials, while achieving coincidence between accuracy and efficiency in computational simulations still remains a challenge. This study utilizes a deep-learning potential, specifically developed for calcium silicate hydrates based on artificial neural network, to achieve molecular dynamics simulations with accuracy comparable to first-principle methods. With this potential, the elastic properties and uniaxial mechanical behaviors are explored, wherein the anisotropy and impact mechanism of calcium ratios are analyzed. The results add to evidence that the deep-learning potential possess a higher accuracy than common force fields. The anisotropy of elastic modulus is mainly attributed to different atomic interactions in various directions, while the anisotropy of strength is additionally affected by the form of failure. This study may advance the accurate molecular-scale simulation and deepen the understanding of the strength source and cohesion mechanism of cement-based materials.

Innovative strategies for time-release PCE design and cement paste flowability control

Extending the retention time of cement paste flowability with the addition of admixtures containing slow-release components is standard practice for ensuring the continued building quality of cement-based materials. This study aims to control the release rate of PCE and enhance its time-varying dispersion effect in fresh cement paste by utilizing Time-dependent Release PCEs (TRPCEs) with varying side-chain structures. The structural characterization of the synthesized TRPCEs was investigated using GPC (Gel Permeation Chromatography), FTIR (Fourier Transform Infrared Spectroscopy), and 1H NMR (Proton Nuclear Magnetic Resonance) techniques. Furthermore, experiments were carried out on time-varying flowability with different dosages of TRPCEs to investigate the flowability changes under the time-varying release effect. The influence of TRPCEs on cement hydration was examined using isothermal calorimetry by measuring the early hydration heat of cement paste. The time-dependent adsorption behaviors of TRPCEs were also examined using a TOC (Total Organic Carbon) analyzer. The findings show that TRPCEs have a minor effect on the cement hydration process's rapid reaction period but little effect on its induction and acceleration periods because of variations in the initial dispersion effect. Additionally, the adsorption behaviors of TRPCEs on cement particles vary significantly due to the hydrolysis of slow-release groups. The varying adsorption and consumption of TRPCEs on cement particles and hydration products in different hydration phases are key controlling factors for the time-varying flowability changes in cement paste. Finally, this innovative approach offers a novel perspective for designing and preparing new types of PCEs with a strong capability for time-varying flowability retention.

Effect of nano-Al2O3 on the mechanical and microstructural properties of cement-based grouting material

The mechanical properties and microstructure of cement-based grouting materials are important parameters affecting the quality of geotechnical engineering, which are limited by the properties of added materials. At present, the exploration of nanomaterials has become the development trend of cement-based grouting materials. The results showed that NA can significantly improve the strength of NCBS. The most pronounced effect was observed when the dosage of NA was 1 %; compared with the control group, the strength increased by up to 45.2 %. NA particles accelerate the hydration reaction rate between cement and fly ash, generating a large amount of hydration products to fill the internal voids of NCBS. When the content of NA was 2–4 %, the strength gradually decreased with an increase in the amount of NA addition. The catalytic and microaggregate effect of the NA particles were the primary contributors to the improved NCBS mechanical properties. Aggregated NA particles were the main cause of the decrease in strength. Acicular ettringite, fibrous calcium silicate hydrate, and NA particles are the dominant components that effect the strength and microstructure of NCBSs. By comparing the relationship between NA and the strength of NCBS and the relationship between the curing age and the strength of NCBS, it was found that NA can better reflect the compressive strength of NCBS, and the correlation degree of NA to the strength of NCBS is 76 % higher than that of the curing age.

Optimization of Electrode Distribution for Detecting Defects in Electrical Resistivity of Embedded Electrode Arrays in Cement-Based Materials

Optimization of Electrode Distribution for Detecting Defects in Electrical Resistivity of Embedded Electrode Arrays in Cement-Based Materials

Synthesis of a chitosan-based superabsorbent polymer and its influence on cement paste

To address the challenge of adaptability between cement-based materials and conventional superabsorbent polymers (sodium polyacrylate, Na-PA), a chitosan-based superabsorbent polymer (CSP) with high salt and alkaline resistance was synthesized, and the optimal synthesis process was determined by a single-factor method. The macroscopic performance and microstructure of CSP and Na-PA were compared, and their influences on cement paste were studied. The results show that CSP exhibits a gradual swelling process during water absorption, which is independent of the solution environment. The poriferous structure of CSP allows it to form a network composed of gel membranes. The introduction of amide group enhances the resistance of CSP to salt and alkaline conditions. The autogenous shrinkage of cement paste is mitigated by CSP, with a superior effect compared to Na-PA. The longer desorption time of CSP allows it to promote cement hydration for a longer period, reducing the loss of compressive strength. The heat release, chemically bound water and hydration products (portlandite and amorphous substances) of CSP pastes are higher than those of Na-PA pastes. The water desorption from CSP fills some middle capillary pores and mesopores, leading to the pores in the hardened cement paste being more concentrated in smaller sizes.

Modelling of water sorption hysteresis of cement-based materials based on pore microstructure

This paper presents a model for predicting water sorption isotherms of cement-based materials. In our model, hysteresis contributions of interlayer pores and gel/capillary pores are calculated separately. The hysteresis model of gel/capillary pores is achieved in four steps: (i) quantification of the pore network, (ii) determination of the criterion of saturation/desaturation of pores, (iii) derivation of the two-dimensional volumetric density distribution function, (iv) calculation of the real-time water content of gel/capillary pores. The hysteresis of interlayer pores is represented by an empirical model based on experiments. The reliability of the model is verified by comparing the model predictions and the experimental data in the literatures. Furthermore, three subjects were discussed: the influence of pore network on hysteresis, the hysteretic behavior of water in pores, the interaction of hysteresis mechanisms.