Cementitious Materials Research Articles

Evaluation of Admixture Silane Added into Cementitious Pastes

This manuscript evaluated the performance of silanes in cementitious matrices in the partial replacement of superplasticizers by silanes. For this, pastes with a water/cement ratio of 0.186 were produced and the superplasticizer admixture based on polycarboxylate esters was partially substituted by three types of silanes—vinyltriethoxysilane silanes (VTES), n-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), and methacryloxypropyltrimethox-ysilane (MCPTMS)—in two substitutions levels (20% and 40%), and then tested in Portland cement pastes. Specific gravity, trapped air, mini-slump, and hydration kinetics (evaluated by isothermal calorimetry up to 48 h) of the pastes were determined in the fresh state. Thus, in the hardened state, the compressive and flexural strength tests (7 and 28 days), specific gravity, and absorption by immersion of the pastes were carried out. The results showed that the substitution of 20% and 40% of VTES and AEAPTMS considerably reduced the workability and increased the air content of the pastes in comparison to the reference sample. In contrast, the incorporation of 20% and 40% of MCPTMS did not significantly affect these properties. The presence of silane, for all analyzed samples, had a delaying effect on the hydration process: the maximum delay verified had a hydration peak in approximately 36 h for the 40% MCPTMS sample and the minimum delay verified had a hydration peak in approximately 11 h for the 20% VTES sample. The replacement of 20% and 40% by any of the silanes progressively reduced the flexural strength at both 7 and 28 days. In the compressive strength, as well as in the tensile strength in flexion, there was a decrease in the results when compared to the reference, except for the MCPTMS, at 7 and 28 days. In immersion absorption, all samples showed high percentages of absorption and void index when compared to the reference.

Pull-out behavior and failure mechanism of steel expansion anchors in high-performance steel fiber reinforced concrete(HPSFRC)

Past research on the pull-out performance of anchors mainly focuses on normal concrete(NC) concretes. New design methods are needed for the pull-out performance of anchors in the concretes of new cementitious materials with high strength and toughness. Accordingly, the pull-out behavior of torque-controlled expansion anchor(TCE) in high-performance steel fiber reinforced concrete(HPSFRC) concrete with different fiber content and installation conditions(embedment depth and anchor diameter) was investigated. The focus was on the failure modes, crack morphology, and load-displacement behavior(including pull-out load-bearing capacity, anchorage stiffness, and anchorage toughness). The addition of fibers leads to increased load-bearing capacity and toughness, reduced stiffness, and all failure modes exhibited ductile cracking and sufficient tensile ductility. Both diameter and depth had a positive impact on load-bearing capacity. A broader database based on literature and this study was analyzed for further exploration of the effects of fibers. The accuracy of predicting load-bearing capacity was compared between two empirical models(concrete capacity design-CCD and Toth models) and the proposed modified model. The CCD model greatly underestimates capacity, and the Toth model is unsuitable for high fiber content(exceeds 2.0 %) HPSFRC scenarios. The modified model showed the best bearing capacity prediction for anchors on HPSFRC concretes, with a mean ratio of predicted values to experimental values reaching 1.01–1.08 and a coefficient of dispersion below 15.0 %.

Enhancing the Mechanical Properties of Ultra-High-Performance Concrete (UHPC) Through Silica Sand Replacement with Steel Slag

In modern construction, increasing the sustainability of materials without sacrificing performance is crucial. Ultra-High-Performance Concrete (UHPC) is known for its exceptional strength and durability. However, incorporating waste and optimizing the mix is still a key focus. The main goal of this article is to evaluate the enhancement of the mechanical properties of UHPC by replacing silica sand with steel slag at various percentages (25%, 50%, 75%, and 100%). With this purpose, we measured the compressive, tensile, and flexural strengths, as well as relative density and water absorption. It was found that the best mechanical performance of UHPC occurs at 50% replacement, exhibiting a maximum compressive strength of 126 MPa (+13.5%), a bending strength of 11.6 MPa (+20.8%), and a tensile strength of 7.2 MPa (+6.5%). Moreover, for the same steel slag replacement, 5.1% decrease in the CO2 eq. emissions was found. However, exceeding the 50% threshold led to a deterioration of UHPC’s mechanical properties, and the SEM images revealed that this was mainly caused by the weakened bond between the cement matrix and the aggregates. Thus, it was concluded that the use of steel slag may significantly improve the structural integrity of UHPC when the adequate replacement percentage is adopted (around 50%), being a viable alternative to traditional aggregates that also has environmental advantages (e.g., reduced carbon emissions).

Experimental studies on strength and workability of mineral admixture modified cement-based fibre-reinforced self-compacting concrete

ABSTRACT Mineral admixtures such as fly ash (FA), ground granulated blast furnace slag (GGBS), metakaolin (MK), and silica fumes (SF) derived from industries are often referred to as secondary cementitious materials, as partial replacements for cement. Also, the use of fibres significantly enhances the flexural behaviour of concrete. Various kinds of literature highlight the performance of concrete with one or two types of admixtures. In this study, an attempt is made to explore the effect of the use of more than two admixtures viz. FA, GGBS and MK as a partial replacement to cement and fibrofor fibre (FF) on workability and strength properties of based Fibre-Reinforced Self-Compacting Concrete (FRSCC). The FF in Self-Compacting Concrete (SCC) is varied from 1.0 to 2.0 kg/cum. The SCC samples are tested for three curing durations. Based on the experimental investigations, the workability of all the mixes is found to be within the EFNARC limits. The variation in the compressive strength of SCC for various fibre dosages is within 10%, after 28 days of the curing period. It is noted that A-10 mix with fibre dosage of 1.0 Kg/cum yielded the highest compressive, split tensile, and flexural strengths after 56 days of curing, as compared to that of all other variations including conventional SCC mix.

Numerical simulation of strengthening/deterioration and damage development of cementitious materials under sulfate attack environment

Cementitious materials exposed to sulfate environments often suffer from the combined effects of external sulfate attack and dry wet cycling. In order to predict the long-term performance of cement-based materials in sulfur rich environments, this paper aims to establish a numerical model that can reasonably characterize the degradation process of cementitious materials in sulfate environments. Using this model, we can address durability problems common to cementitious materials in real sulphate environments, such as determining the degree of corrosion, predicting the durability life of materials, and calculating the time to failure. The model consists of three parts: transportation, chemical reactions, and material damage. We establish the degradation model for cement-based materials in sulfate environments by considering ion diffusion, water convection, chemical reactions, accumulation of corrosion products, and the development of material strengthening/degradation. Compared with existing sulfate corrosion models, this model not only considers ettringite, but also takes into account the volume changes of gypsum formation, calcium leaching, and salt crystallization precipitation, which can more reasonably simulate the sulfate corrosion process in real environments. The model can reasonably simulate the distribution pattern of ion concentration, hydration products and corrosion products in the cementitious material, and on this basis calculate the porosity of the cementitious material. In order to make the simulation results more applicable to experimental and non-destructive testing results, the model uses easily obtainable relative dynamic elastic modulus to evaluate the degree of material strengthening/degradation and predict the durability life of the material.

Research Progress on the Activity Stimulation of Lithium Slag in Concrete

Lithium slag (LS), an industrial waste byproduct generated during lithium salt production, is characterized by its harmful trace elements, significant stockpiles and low pozzolanic activity. By 2003, the annual discharge of lithium slag in China surpassed 15 million tons, creating an urgent need for established large-scale disposal technologies. One of the primary strategies for the effective utilization of LS is its application as an auxiliary cementitious material in concrete. However, the low reactivity of LS and challenges associated with its large-scale application impede its effective utilization. Enhancing the pozzolanic activity of LS is pivotal for its substantial incorporation into concrete. This study begins by analyzing the physicochemical properties and volcanic ash reactivity of LS derived from various lithium extraction techniques. It subsequently explores the diverse activation techniques aimed at improving the reactivity of LS within concrete. Ultimately, this paper highlights the significance of synergistic activation strategies, particularly physicochemical co-excitation and multi-exciter composite excitation. These approaches are identified as critical pathways for enhancing the activity of LS. Through this exploration, this study aims to unveil innovative strategies that bolster the resource utilization efficiency of LS, thereby facilitating its effective application in the concrete domain.

Effect of carbonation curing on the characterization and properties of steel slag-based cementitious materials

Steel slag (SS)-based cementitious materials usually exhibit poor bulk stability, poor early activity and low mechanical strength, which greatly limits the consumption of SS in construction materials. Carbonation curing can not only control volume expansion but also improve the mechanical properties and durability of SS-based cementitious materials. First, the physicochemical properties of the SS were summarized. Then, the reaction mechanism of carbonation curing was analyzed. Next, the mineral composition, microstructure, morphology and CO2 uptake of the SS-based materials during carbonation curing were discussed, and the effects of carbonation curing on the mechanical properties, volume stability and durability of the SS-based materials were investigated. Finally, some suggestions for the application of carbonation curing in SS-based materials were given. The development and application of carbonation curing in SS-based materials can achieve the large-scale utilization of SS in cementitious materials and the effective reduction of CO2 emissions.

Investigation on the mechanical and microstructure properties of masonry cement-red mud-carbide slag-based paste

The high alkalinity and complex phase composition of red mud pose significant challenges for its direct utilization. The construction industry is widely regarded as the most viable option for large-scale consumption of red mud to mitigate its continuous accumulation globally. Activation treatment is a crucial prerequisite for preparing cementitious materials from red mud, but traditional methods either require high-temperature calcination of red mud or the use of substantial amounts of strong alkaline substances as alkaline activators, thereby increasing costs and hindering the large-scale application of red mud. This paper presents an alternative method where 4% carbide slag is used as an activator to prepare cement-red mud-carbide slag-based composite pastes, substituting 10%-90% of masonry cement with red mud. As the red mud content increases, the compressive and flexural strengths of the hydrated pastes significantly decrease; the compressive strength of the material with 10% red mud is 13.4 times that of the material with 90% red mud. The addition of 4% carbide slag enhances the compressive and flexural strengths of the red mud-based cementitious material, with increases of 1.67%, 17.9%, and 34.6% in compressive strength at 3d, 7d, and 28d, respectively, and increases of 2.38%, 6.67%, and 7.36% in flexural strength. This indicates that carbide slag is beneficial for activating the reactivity of red mud. There is an incremental relationship between the flexural and compressive strengths of the cementitious material, and a fitting formula can be used to quantify the relationship between red mud content and these strengths. Microstructural analysis confirms that the addition of carbide slag significantly optimizes the pore structure, promoting the formation of Ca(OH)2 and C-S-H gel, which leads to improved mechanical properties of the red mud-containing composites. This study provides a feasible solution for the large-scale application of red mud in the cement industry.

New impulse-based test method for early-age elastic modulus measurement in cementitious materials

Accurate monitoring of the elastic modulus evolution during the early-age fluid-solid transition in cementitious materials is crucial for understanding their mechanical behavior under early stresses. While existing methods, such as EMM-ARM, have proven effective, they are often associated with high costs or complex setups. This study presents the development of a low-cost, easy-to-implement system that employs impulse excitation applied to a composite beam, introducing the EMM-IRM method for the effective assessment of the elastic modulus of cement paste from the earliest stages of hydration. The use of impulse excitation is particularly advantageous in low-cost systems with accelerometers of lower sensitivity, as it enhances signal clarity and reduces interference from background noise, thereby improving measurement reliability. The system was validated through experimental comparisons with conventional EMM-ARM, cyclic compression, and traditional impulse excitation techniques, using Portland cement paste as the test material. The results show that EMM-IRM consistently estimates the elastic modulus, with a maximum deviation of 6.33% from other methods. Moreover, despite its cost-effectiveness, EMM-IRM demonstrates a higher signal-to-noise ratio compared to conventional EMM-ARM. This approach offers a practical solution for early-age characterization of cementitious materials, balancing cost, simplicity, and measurement accuracy.

3d Mapping Of Stiffness Evolution Of Hardening Concrete With Saps Using Elastic Wave Tomography

Phenomena occurring during the delicate phase of concrete curing can have a strong influence on the final mechanical properties. Therefore, monitoring the changes during hydration can provide meaningful information on the material properties. Lately, non-destructive techniques have received great attention for monitoring earlyage concrete. This paper aims to assess the ultrasonic velocity and stiffness development of hardening concrete during various curing stages using the Elastic Wave Tomography (EWT) technique. The monitoring of the curing process starts as soon as seven hours after casting and lasts up to seventy hours. A three-dimensional (3D) wave velocity map is created, and conventional concrete is compared to concrete containing SuperAbsorbent Polymers (SAPs), a novel admixture used for shrinkage mitigation by providing internal curing in the cementitious matrix. However, SAPs have been proven to reduce compressive strength when added to concrete, due to the increased porosity they induce. This porosity may also result in the reduction of the wave velocity. However, the internal curing provided by the SAPs can promote the formation of new hydration products in the matrix and thus (partly) compensate for the strength loss making the uniformity of the internal curing another important point of concern. EWT can provide global information on the homogeneity of the influence of the SAPs in the cementitious matrix as opposed to the wave velocity of a single wave path that is usually examined in practice. In addition, the determination of the early-age stiffness evolution can be connected to the final mechanical properties of the material. The dynamic Young’s Modulus is calculated and compared to the static Young’s modulus at 28 days. Predictions towards the static Young’s modulus are also made, showing good agreement.

Nitric acid-modified amorphous alloy fiber and its effects on mechanical properties of ultra-high performance concrete (UHPC)

The traditional steel fiber UHPC has the phenomenon of low strength and poor durability, which can not give full play to the practical value of UHPC. Nevertheless, amorphous alloy fibres possess notable strength, flexibility and corrosion resistance. The incorporation of amorphous alloy fibres into ultra-high performance concrete (UHPC) has been demonstrated to enhance the strength and toughness of UHPC. However, the surface of amorphous alloy fibres is characterised by a smooth and hydrophobic quality, which presents a challenge in terms of the interface bond with the cement matrix. In order to address this issue, three concentrations of nitric acid (HNO3, 2 mol/L, 4 mol/L and 6 mol/L) were employed to modify the surface of amorphous alloy fibres, and then the amorphous alloy fibres were incorporated into the cement matrix for fiber pull-out test, compression, flexural strength and impact testing. The changes in the physical and chemical properties of the amorphous alloy fibres before and after modification were analysed, and the effects on the interface bond strength and dynamic and static mechanical properties of UHPC were studied by means of SEM. The results demonstrate that the adhesion strength of the modified amorphous alloy fibre with 4 mol/L HNO3 is the most robust, with an increase of 18.7 % in compressive strength, 13.8 % in flexural strength, and 5.4 % in impact resistance. The method has been demonstrated to be effective in strengthening and toughening the cement matrix with HNO3-modified amorphous alloy fibres.

Blast response and protection level of concrete composite wall panels made with recycled tyre fibres in a cement matrix

This paper investigates the blast response and protection level of a new blast-resistance wall panels made of Recycled Tyre Fibres Concrete (RTFC) as an exterior protective layer compositely connected to a concrete wall through experiments and numerical modelling. RTFC is a novel sustainable cement-based versatile composite, made with recycled non-biodegradable material (tyre rubber particles) in the form of composite fibres in a cement matrix, with applications in blast and ballistic protection that features high dynamic properties. Three composite wall panels were constructed and subjected to blast loads generated by Advanced Blast Simulator (ABS). Three different loading scenarios, each with an intensity capable of causing complete structural failure, were applied. The blast wave characteristics, such as the imposed overpressure and impulse, were measured alongside the deflection of the specimens. The wall specimens could withstand the blast loads with minimal damage. No cracks were observed in the RTFC layer, with only minor cracks appearing on the concrete side of the wall. The protection performance of the wall specimens was examined following UFC guidelines, revealing their outstanding resistance to blast loads. Moreover, in line with these guidelines, the composite wall panel is eligible for a High Level of Protection (HLoP) classification. Finally, a Single Degree of Freedom (SDOF) analytical model was developed for the wall panel to determine the Dynamic Increase Factor (DIF) of RTFC. The analysis resulted in a DIF value of 1.5, which was then incorporated into the numerical models of the walls. The accuracy of the DIF was validated by comparing the numerical results with experimental data, confirming its reliability.

Effect of cementitious capillary crystalline waterproof material on the mechanical behavior of concrete

Cementitious capillary crystalline waterproof material (CCCW) is a material that can react with substances inside the concrete, generating crystals that fill the pores and cracks in the concrete. This chemical reaction is expected to improve the mechanical properties of the concrete. This study investigated the effects of CCCW content and water-cement ratio (W/C) on the compressive behavior of cementitious capillary crystalline waterproof concrete (CCCWC). The results indicated that as the CCCW content increased from 0% to 1.5% for W/C of 0.4, the compressive and tensile strength values of concrete slightly decreased. This is because excessive CCCW generates too many crystals within the concrete, leading to internal matrix expansion and crack formations. However, in the cases of W/C of 0.45 and 0.5, the compressive and tensile strength values of the CCCWC increased wit increasing CCCW content from 0% to 0.5%, but declined with 1.5% CCCWC addition. The reaction between CCCW and concrete generates numerous crystals, which densify the concrete matrix and enhance its strength. Moreover, with increasing W/C, the CCCWC's compressive strength and tensile strength decreased due to the increased porosity of the concrete matrix and the reduced availability of the concrete constituents that react with CCCW. Furthermore, the appropriate choice of CCCW content and W/C can significantly enhance the slope and peak stress of the stress-strain curve. Based on this, a compressive constitutive model of CCCWC was established. The findings showed that the optimal CCCW content varied with W/C. For instance, for a W/C of 0.4, the maximun compressive strength of 54.82 MPa was achieved without any CCCW addition. In contrast, the addition of 0.5% CCCW to concrete produced with W/C of 0.45 and 0.5 resulted in the highest compressive strengths of 50.98 MPa and 44.90 MPa, respectively.

Effect of N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt and triethanolamine on the hydration and compressive strength of steel slag-cement composite systems: A comparative study

To solve the problem of low cementitious activity of steel slag (SS), N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt (BES-Na) and triethanolamine (TEA) were used in this study to improve the hydration activity of SS. However, there are no comparative studies on the effects of BES-Na and TEA on the hydration of SS-Portland cement (PC) systems. This study compared the hydration process and strength development of SS-PC systems in the presence of BES-Na and TEA, as well as the complexing ability of BES-Na and TEA. The results showed that both BES-Na and TEA improved the early compressive strength of SS-PC mortar, but TEA did not contribute to the late compressive strength, while BES-Na still improved the late compressive strength. At the same dosage, TEA accelerated aluminates hydration more than BES-Na and retarded/inhibited silicates hydration more than BES-Na. This difference in effect on hydration can be attributed to the difference in their complexing ability. TEA has a stronger complexing ability with metal ions than BES-Na, which is beneficial for accelerating aluminates hydration, but this not only prolonged the hydration induction period but also inhibited silicates hydration. BES-Na has a weaker complexing ability relative to TEA. Although BES-Na has a weaker accelerating effect on aluminates hydration, it has a lesser effect on silicates hydration and even accelerates silicates hydration at low dosage. This study also showed that BES-Na is an alternative additive to TEA, which could help expand the application of BES-Na in cementitious materials.

Recycling and optimum utilization of CRT glass as building materials: An application of low CO2 based circular economy for sustainable construction

The construction industry is the major contributor of CO2 emission around the globe. The rapid advances in the electronics industry have transformed the disposal of cathode ray tube glass waste (CRT-WG) into a prominent environmental concern. Recycling of CRT glasses as building materials can help in the production of sustainable construction. Numerous previous studies have documented that CRT-WG can be utilized either as a component of fine aggregate or binder material as it provides a cleaner solution and reduce carbon emission. Under this cleaner production and low CO2 emission perspective, this paper provides a thorough review of the previous studies on the utilization of CRT glass as a partially and fully substitute of sand and cementitious material in mortar production and propose an application of CO2 based circular economy model for reduce carbon emissions. This paper summarized the fresh, mechanical and durability properties of mortar incorporating treated and un-treated CRT-WG with different mineral additives and w/b ratios. Furthermore, this research explores the optimal proportions of CRT glass that can be use as replacements for sand and cement powder to make eco-friendly and sustainable low carbon mortar suitable for both structural and non-structural applications. More particularly, this review emphasizes the benefits, the need for additional research, and the drawbacks of CRT-WG use in construction building. Overall, this study proposes that incorporating CRT glass into building materials through a low CO2 based circular economy offers significant potential advantages. This study will help in optimization of CRT glass in concrete mix design in combination with waste materials for sustainable construction.

Improved mechanical and microscopic properties of ultra-high-performance concrete with the addition of hybrid alkali-resistant glass fibers

Ultra-high-performance fiber-reinforced concrete (UHPFRC), wherein steel fibers are a primary component, is a new cementitious material with high tensile strength and impact resistance. However, steel fibers are susceptible to corrosion in the alkaline environment of concrete matrices. By contrast, alkali-resistant glass fiber (ARGF) exhibits better corrosion resistance. However, few studies have explored the effects of ARGF on UHPFRC, leaving the optimum ARGF content and its enhancement mechanism unclear. Therefore, this study proposes a UHPFRC design that utilizes AR-GF in place of steel fibers. The effects of different types, lengths, and admixtures of AR-GF are investigated using mechanical tests, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that the splitting tensile strength and flexural strength of the UHPFRC increase with fiber length and fiber dosage. The optimum fiber mixing ratio is 30 kg/m3 of 12 mm-long Anti-Crak® 62.4 combined with 0.05 kg/m3 of 6 mm long Anti-Crak® HD, leading to a 23.3 % increase in splitting tensile strength and 15.8 % increase in flexural strength compared to those of undoped concrete. By analyzing the ARGF dispersion pattern at the fracture surface of the flexural test, the ARGF dispersion analysis method was proposed. SEM shows that the ARGF is coated with C-S-H, which increases its adhesion to the concrete matrix. XRD confirms that ARGF does not affect the hydration reaction of the cement in the UHPFRC. Finally, a model of ARGF-reinforced UHPFRC is established to elucidate the reinforcing mechanism. This study provides guidance and a reference for the application of UHPFRC in engineering projects.

Exploring effects of supplementary cementitious materials on setting time, strength, and microscale properties of mortar

The concept of sustainability has become a crucial concern for safeguarding the planet. The current research has focused on developing affordable and eco-friendly mortar by using industrial wastes. This study explores the use of fly ash (FA) and ground granulated blast furnace slag (GGBFS), byproducts of steelmaking and coal burning, in mortar production. It examines their impacts on the compressive strength and setting times, when utilizing varying proportions of the materials. The study also evaluates water requirements for the workability, thus demonstrating the sustainability of these waste products in construction. The cementitious materials were employed in finely ground form and were replaced with further tertiary mixes including both supplements at 10%, 30%, and 50% of each. The mixtures were allowed to cure for 7, 14, and 28 days by immersion in water. The results showed improvements in the compressive strength of mortar samples incorporating FA and GGBFS at various curing ages. However, the water requirement and workability of mortar samples were altered as a result of utilizing these supplementary cementitious materials (SCMs). These findings will serve as a standard for environmentally responsible mortar using GGBFS and/or FA as SCMs.

Self-healing and wave-absorbing functional coupling of nano-Fe3O4 hybridized microcapsules

As a common high-performance wave absorber, the application prospect of nano-Fe3O4 in cementitious materials is limited due to its defects such as easy agglomeration and possible hydration reaction with cement clinker. In this study, self-healing and wave-absorbing functional coupling materials were synthesized by nano-Fe3O4 hybridized microcapsules. The physical and chemical properties of nano-Fe3O4 hybridized microcapsules were characterized by ESEM (Environmental scanning electron microscopy), XRD (X-ray diffractometer) and FTIR (Fourier transform infrared spectrum), etc. The self-healing properties of microcapsules were assessed. The electromagnetic parameters of microcapsules were measured, and the wave-absorbing performance of microcapsules with different matching thicknesses was assessed. The function coupling mechanism of self-healing and wave-absorbing of microcapsules hybridized by nano-Fe3O4 was revealed. The findings revealed that the residual weights of FM0 and FM40 were 1.28 % and 16.44 %, respectively. The hybrid microcapsules demonstrated the amorphous structure of self-healing microcapsules and the crystal structure characteristics of nano-Fe3O4. The highest strength healing rate of cement mortar mixed with microcapsules was 34.2 %. The minimum reflection loss and the corresponding effective bandwidth of the nano-Fe3O4 hybridized microcapsules with a thickness of 3 mm were −20.32 dB and 7.07 GHz, respectively. The nano-Fe3O4 hybridized microcapsules with core–shell structure exhibit excellent wave-absorbing performance through the functional coupling of dielectric loss and magnetic loss.

A cohesive fracture-enhanced phase-field approach for modeling the damage behavior of steel fiber-reinforced concrete

This study introduces a novel computational framework based on the phase-field fracture/damage model (PFM), providing rapid and accurate predictions of the damage behavior of Steel Fiber Reinforced Concrete (SFRC) material. The framework integrates the interfacial cohesive fracture model with the PFM to depict the interaction between the cementitious matrix and fibers, marking the first demonstration that this model adequately captures both local fracture phenomena between fibers and concrete (such as fiber bridging and interfacial debonding) and mesoscopic stress–strain behavior. Additionally, an enhanced geometric approximation is established based on the spatial distribution density function of fibers and particles, allowing for the transformation of the three-dimensions (3-D) fiber-reinforced material structure into an equivalent two-dimensions (2-D) material. This approach enables the reduction of computational time, a significant limitation of the phase-field method, thereby allowing an in-house code to perform various computations with complex material structures such as SFRC. The effectiveness of the approach is demonstrated through four examples involving variations in the microgeometry and material properties of SFRC structures, ranging from the simplest configurations to real experimental material structures. Extensive Monte Carlo simulations of the model are also employed to provide results closer to reality, which are then compared with recent experimental data and numerical models, demonstrating the efficacy of the proposed computational model.

LC3 cementitious binder incorporating microencapsulated phase change materials for self-defrosting traffic surfaces

Exposed surfaces of bridge decks, viaducts and pavements incur ice formation and accumulation of snow in cold seasons, which threatens traffic safety. Mitigating this problem using traditional methods such as deicing salts have caused ecosystem damage and inflicted substantial reinforcement corrosion and surface scaling to bridge decks and pavements, thus compromising their service life and causing colossal economic loss. This paper presents an alternative solution to overcome this problem through the development of a sustainable LC3 cementitious material incorporating micro-encapsulated phase change material (MEPCM) with low phase transition temperature to delay the surface temperature drop and mitigate snow accumulation and ice formation. MEPCM was incorporated in the cementitious matrix at 0 %, 10 % and 20 % by binder mass. Paste and mortar mixtures were prepared to investigate the microstructural, mechanical, physical, and thermal properties. Test results showed that incorporating MEPCM in the LC3 matrix achieved adequate compressive strength. Thermal simulations and visual observations conducted on mortar samples in the laboratory and outdoor exposure showed that MEPCM can effectively regulate the surface temperature of the LC3 matrix and mitigate temperature drops as well as snow accumulation. Analysis of temperature data in the 2023–2024 winter season of Hamilton, Ontario, Canada indicated that the MEPCM incorporated in mortar samples could effectively regulate 40 % of the total days considered and mitigate surface ice formation and snow accumulation, which provides both economic and environmental benefits.