Search Results (290)

Ambient-temperature asphalt binders have emerged as a sustainable alternative to traditional hot-mix asphalt, offering significant advantages in energy conservation and emission reduction. This review systematically examines the research progress and development trends of high-performance reactive asphalt binders designed for ambient-temperature application, which achieve enhanced performance through chemical cross-linking reactions. The study focuses on three core material systems: epoxy resin, waterborne epoxy emulsified asphalt, and polyurethane. For each system, we comprehensively summarize the material composition, strength formation mechanisms, and mix design methodologies. Key evaluation methods for critical pavement performance—including strength characteristics, water stability, and high-temperature performance—are critically reviewed. Furthermore, microscopic characterization techniques including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) are discussed to elucidate the underlying mechanisms governing performance evolution. Analysis reveals that epoxy-based binders exhibit superior strength and stiffness, rendering them suitable for heavy-traffic pavements; waterborne epoxy emulsified asphalt binders combine environmental compatibility with construction convenience for thin-layer rehabilitation, while polyurethane-based binders demonstrate exceptional elasticity and rapid curing characteristics for quick-traffic-opening scenarios. Although current research has established a preliminary performance evaluation framework, the absence of unified technical standards constrains widespread engineering implementation. Future research priorities should focus on developing water-triggered curing systems, intelligent responsive materials, and comprehensive standardization systems to fully harness the engineering potential of these sustainable binders. Full article

Low-lime calcium silicate cement develops strength mainly through carbonation curing. However, long curing times can limit precast productivity. This study examined whether recycled coarse aggregates promote carbonation in CSC concrete via porous adhered mortar, which facilitates CO₂ transport. Two mixes (CSC replacement 50%, W/B 0.45) were prepared: NCA-CSC50 and RCA-CSC50 (100% NCA replacement). After steam curing, the specimens were carbonated in 20% CO₂ at 20 °C and 60% RH for 1–14 days. The carbonation degree was quantified from phenolphthalein-sprayed cross-sections by image binarization, and depth-dependent phase evolution and ITZ changes were assessed by XRD and SEM–EDS. RCA-CSC50 exhibited a higher carbonation degree and coefficient and achieved higher compressive strength, exceeding those of NCA-CSC50 after 3 days. XRD analysis performed after 14 days of carbonation curing revealed that portlandite peaks remained in NCA-CSC50 at depths of 35–50 mm, whereas they were not detected at the same depths in RCA-CSC50, indicating more extensive carbonation penetration in the RCA-containing mixture. This result is consistent with the quantitatively higher carbonation degree and carbonation coefficient of RCA-CSC50 compared with NCA-CSC50. SEM–EDS observations further revealed multiple ITZs around the recycled aggregate. Although the ITZs were not directly quantified as CO₂ diffusion paths, their presence is likely associated with the enhanced carbonation observed in RCA-CSC50 by providing additional connected zones for CO₂ ingress. These findings suggest that RCA can be considered not only as a recycled aggregate source but also as a potential means of facilitating CO₂ transport in carbonation-cured CSC concrete. Furthermore, the combined use of carbonation-reactive binders and recycled aggregates is expected to contribute to the broader application of low-carbon concrete technologies by reducing construction waste and expanding the implementation of CCUS-based approaches. Full article

In this article, binders containing 0, 40 and 80 wt% calcined common clay are investigated in pastes, mortars and concretes. The investigation covers heat flow, microstructural aspects, compressive strengths, carbonation and sustainability calculations. The initially slow pozzolanic reactivity of the calcined common clay causes a decline of the 2-day strength exceeding its replacement level. As the pozzolanic reaction develops with time, concretes with 40 wt% binder replacement achieve up to 10% higher strengths than their reference at day 90. A further increase in the replacement to 80 wt% calcined clay yields concrete strengths that are at least 30% lower than the reference, because portlandite lacks for a complete pozzolanic reaction of the calcined common clay. This is counteracted by adding hydrated lime, which improves strength by up to 10 MPa. Microstructural investigations substantiate the strength findings. As the amount of hydrated phases declines and porosity rises, strength decreases, and vice versa. Replacing 40 or 80 wt% of Portland cement by calcined clay reduces the Global Warming Potential of concretes by nearly a quarter or half. The concretes with 40 wt% replacement exhibit the best strength eco-efficiency from day 28 onwards, while the concretes with 80 wt% replacements achieve a strength eco-efficiency comparable to that of the reference concretes. Full article

The cement industry plays a critical role in infrastructure development, but is a major contributor to CO₂ emissions, driving the search for low-carbon binders that can also valorize industrial wastes. This review examines the engineering performance of red mud (RM)-based binder systems, highlighting the relationships between mixture design, processing, fresh-state behavior, mechanical properties, durability, and microstructural evolution. Special attention is given to how RM’s particle characteristics and mineralogical/chemical composition influence reactivity during geopolymerization, thereby affecting strength development and pore structure. Across the literature, moderate RM incorporation (commonly ≤15–20%) generally preserves workable fresh properties and adequate compressive strength, whereas higher RM contents (≥30%) often increase total porosity and pore connectivity, resulting in reductions in strength and durability. To mitigate these drawbacks, effective strategies such as thermal activation of RM and synergistic blending with supplementary cementitious materials like ground granulated blast-furnace slag and phosphogypsum are consistently reported to enhance reaction extent, densify the gel matrix, refine pore structure, and improve long-term durability. Overall, RM-based cementitious binders demonstrate considerable potential for both structural and non-structural applications; however, further research is needed on long-term performance under realistic exposure conditions, scale-up and quality control to address RM variability, and performance-based mix design guidelines to support reliable field implementation. Full article

Current antibacterial sprays face major limitations, including rapid evaporation, short-lived efficacy, skin irritation, and poor adhesion to surfaces, highlighting an urgent need for a durable and biocompatible alternative. To address these challenges, we developed a ZIF-8-based spray (ZNS-WO20) composed of ZIF-8 nanoparticles dispersed in 50% ethanol and 20% OTES. OTES acts as a dispersant and binder, enabling wash-resistant coatings on gauze and glass. ZIF-8 exhibits pH-responsive Zn²⁺ release, achieving nearly 100% killing of S. aureus, E. coli, and methicillin-resistant S. aureus (MRSA) at 160 μg/mL through intracellular reactive oxygen species (ROS) generation. The spray maintains >95% antibacterial efficacy against S. aureus after five washing cycles and seven days of outdoor exposure, and causes no dermal irritation in rats. This work fills the gap for a long-lasting, skin-friendly antibacterial spray, showing promise for healthcare disinfection and surface protection. Full article

To promote the synergistic utilization of phosphogypsum (PG), steel slag (SS), and fly ash (FA), a ternary all-solid-waste binder, namely PG-SS-FA cementitious material (PSA), was prepared. The effects of SS content on workability, setting behavior, mechanical properties, hydration products, pore structure, and microstructure were systematically investigated. The results showed that increasing SS content continuously reduced the fluidity of PSA, while the setting time first shortened and then increased. The fastest setting was observed at 40% SS, with initial and final setting times of 126 and 321 min, respectively. Increasing SS from 20% to 40% enhanced the hydration reaction, promoted the formation of AFt and C-(A)-S-H gel, reduced residual unreacted phases, and refined the pore structure, resulting in the highest compressive and flexural strengths for M40. However, further increasing SS to 60% and 80% reduced the fly ash proportion and limited the sustained supply of reactive Si/Al species, despite increasing Ca²⁺ availability and alkalinity, thereby restricting later-age gel accumulation and pore refinement and ultimately weakening mechanical performance. Overall, the performance evolution of PSA is governed by the coupled effects of alkali/Ca supply from SS, sulfate supply from PG, and reactive Si/Al supply from FA. The optimal performance at 40% SS is attributed to the synergistic construction of an AFt framework and continuous pore filling by C-(A)-S-H gel. Full article

Magnesium oxychloride cement (MOC), produced from reactive MgO and MgCl₂, has re-emerged as a promising low-carbon binder due to its rapid setting and high early-age strength. Yet its limited resistance to moisture and immersion remains the principal barrier to broader construction deployment. This review synthesizes the MOC evidence base using a structured approach that combines PRISMA-informed study identification and screening with bibliometric mapping to contextualize research evolution and thematic development. The review follows a structured data extraction of mix design, curing conditions, characterization methods, and performance outcomes. The synthesis confirms that MOC performance is strongly system-dependent. MgO reactivity, MgCl₂ concentration, mixture ratios, and curing regime govern hydration products, microstructure, and durability, accounting for the apparent variation across studies. Comparative assessment shows that improvements in water resistance are most consistently reported for phosphate-based modification, SCM incorporation, and polymer/hybrid strategies. However, benefits are frequently accompanied by trade-offs in workability, setting, strength development, and cost, and reinforcement compatibility and corrosion risk remain insufficiently resolved for structural applications. The review highlights gaps in reporting and durability testing that currently limit cross-study comparability and translation, and it consolidates priority research directions toward standardized protocols, mechanism-based durability design, scale-up validation, and robust sustainability assessment. Full article

Population growth and rapid urbanization have significantly increased construction activities and the demand for building materials. It is estimated that approximately 39% of global CO₂ emissions are associated with the construction sector, with nearly 8% directly attributed to Portland cement production. In addition to greenhouse gas emissions, the cement industry is responsible for substantial environmental impacts, including natural resource depletion, soil degradation, and air and water pollution. In this context, the development of alternative and more sustainable binder systems has become a global research priority. Geopolymers have emerged as promising materials produced through either alkaline or acid activation routes, offering advantages such as a reduced carbon footprint, high durability, and rapid strength development. Among these systems, acid-activated materials, particularly phosphate-based geopolymers, differ fundamentally from conventional alkali-activated binders in terms of reaction chemistry and binding phases. The formation of aluminum phosphate (AlPO₄) networks plays a key role in governing the mechanical performance and microstructural stability of these materials. This mini-review provides a critical overview of the fundamental principles of acid activation applied to alternative cementitious materials, with emphasis on dissolution mechanisms, polycondensation reactions, and the nature of binding phases in phosphate-based systems. Unlike previous reviews, this study integrates recent findings on reaction mechanisms with a comparative analysis between acid and alkaline activation routes, highlighting underexplored aspects of precursor reactivity and binder formation. The main types of acids used as activators, the influence of precursor chemical composition, and the conceptual differences between acid and alkaline activation are discussed. In addition, recent advances, current challenges, and future perspectives of acid activation are addressed, highlighting its potential as a viable low-carbon binder route for sustainable construction materials, with strong prospects for partially replacing Portland cement, particularly in high-performance applications requiring enhanced chemical resistance and thermal stability. Full article

This study provides new experimental evidence indicating that powdered mineral wool waste traditionally classified as a non-reactive, non-recyclable insulation residue can function as a genuinely pozzolanic supplementary cementitious material when incorporated into Portland cement systems. Unlike previous work that has treated mineral wool exclusively as an inert filler, this research demonstrates that its amorphous silicate–aluminate phase becomes chemically active under high-alkalinity conditions. A combined experimental programme, including mechanical testing, assessment and SEM/EDS microstructural analysis, was used to evaluate replacement levels of 20%, 25%, and 40% in CEM I mortars, with CSA cement employed as a contrasting binder system. The results indicate a potential contribution of powdered mineral wool to strength development; however, this effect cannot be unequivocally attributed to pozzolanic activity alone. It may also be partially related to physical effects such as filler action and particle packing. SEM/EDS observations confirm the formation of secondary C–S–H and C–A–S–H gels, can function as a genuinely pozzolanic supplementary cementitious material. Therefore, the applied assessment approach should be treated as indicative, and further verification using complementary methods is required. This study provides new experimental evidence indicating mineral wool can potentially contribute to cementitious performance as a Supplementary Cementitious Material (SCM). However, these observations should be treated as qualitative and indicative rather than definitive proof of pozzolanic reaction. The study provides an environmentally relevant valorisation pathway for a problematic waste stream, showing that mineral wool residues containing only trace levels of immobilizable formaldehyde can be safely and effectively integrated into low-carbon binder technologies. These findings position powdered mineral wool as a previously overlooked, yet technically viable SCM, offering new opportunities for clinker reduction, waste circularity and sustainable cementitious material design. Full article

The transition toward low-carbon and resource-efficient construction materials has intensified interest in geopolymer binders incorporating industrial and post-consumer wastes. Waste glass powder (WGP), a silica-rich component of the global glass waste stream, has emerged as a promising circular-economy precursor in alkali-activated systems; however, reported durability trends remain inconsistent and are often interpreted without mechanistic integration. This review synthesises current knowledge of WGP reactivity, gel chemistry, and long-term performance through an explicit reaction–transport–ageing (R–T–A) framework that links dissolution behaviour and phase assemblage development to pore connectivity, ion ingress, and time-dependent degradation. Under alkaline activation, the amorphous structure of WGP promotes silica release, modifying Si/Al ratios and governing the formation of N-A-S-H or hybrid N-A-S-H/C-(A)-S-H gels. These reaction products determine transport characteristics and ageing evolution, which collectively control chemical resistance, chloride ingress, alkali–silica reaction-type instability, and dimensional stability. Variability across studies is shown to arise from imbalances in particle fineness, replacement level, precursor chemistry, and activator design rather than intrinsic inconsistency in WGP behaviour. The R–T–A framework clarifies how reaction completeness, pore network architecture, and long-term phase stability interact to produce system-dependent durability outcomes. WGP demonstrates strong potential as a circular-economy precursor in alkali-activated binders; however, reliable structural application requires durability-informed mix design grounded in coupled reaction–transport–ageing mechanisms and supported by extended exposure testing under realistic service conditions. Full article

Calcium silicate hydrate (C(-A)-S-H) and its aluminosilicate counterpart (C-A-S-H) constitute the principal binding phases in Portland cement and blended systems, governing mechanical strength and durability. This paper presents a summary of the work related to dehydration of C(-A)-S-H and rehydration of dehydrated C(-A)-S-H. Their thermal dehydration, a key process for cement recycling, induces profound multi-scale transformations: at the atomic level, it alters calcium and aluminum coordination environments and disrupts chemical bonding; at the chain-structure level, it causes depolymerization of the silicate/aluminosilicate networks; and at the microstructural level, it leads to changes in nanoscale particle morphology, aggregation state, and pore structure, creating a metastable, defect-rich, high-energy state distinct from the original C(-A)-S-H. The subsequent rehydration of this dehydrated C(-A)-S-H, which is not a simple reversal but a distinct dissolution–precipitation process, enables microstructural reconstruction and restored reactivity upon contact with water. This rehydration capacity is fundamentally exploited in thermally activated recycled cement—a novel binder concept that leverages dehydration-induced metastability for renewed strength development. Understanding these interconnected processes, influenced by factors like temperature, humidity, rate, and aluminum content, is critical for advancing sustainable cement technology, enabling the design of high-performance recycled cement and concrete, and facilitating the recycling of cementitious materials. Full article

Organic coatings are used as one of the most effective strategies for the corrosion protection of metals. Nowadays, due to environmental regulations, the use of water-based coatings has become essential compared to solvent-based ones. However, their application to magnesium alloys remains largely unexplored due to their high reactivity with water. In the present work, a phosphate-functionalized waterborne binder is applied to AZ31B magnesium alloy. The surface has been modified by four different pre-treatments, respectively: (i) mechanical grinding, (ii) pickling, (iii) conventional conversion treatment, and (iv) a novel conversion treatment based on layered double hydroxides (LDH). The most promising pre-treatments are selected to explore their synergy with a biobased waterborne binder, containing CeO₂ nanoparticles as a corrosion inhibitor. The morphology and composition of the different systems are studied, prior to and after corrosion tests in NaCl solution, by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results obtained by electrochemical impedance spectroscopy (EIS) in NaCl solution have revealed not only that LDH performs better than the conventional conversion treatment but also the synergy between LDH pre-treatment and CeO₂ nanoparticles when two organic layers are used. Full article

Peptidyl arginine deiminase 4 (PAD4) is a Ca²⁺-dependent enzyme that catalyzes histone citrullination and plays a central role in chromatin decondensation during neutrophil extracellular trap (NET) formation. Dysregulated PAD4-mediated NETosis contributes to the pathogenesis of diverse inflammatory and immune-related diseases, including autoimmune disorders, cancer, and thrombosis. Although several synthetic PAD4 inhibitors have been developed, their therapeutic application has been limited by issues related to selectivity, irreversible covalent reactivity, and suboptimal pharmacokinetic properties, prompting growing interest in natural products as alternative modulators of PAD4 activity and NETosis. This article presents a structural and mechanistic overview of natural products that target PAD4 and regulate NETosis. Based on enzyme kinetics, structural analyses, and functional validation, natural PAD4 modulators are classified into four categories: (i) active-site-directed inhibitors that bind within the U-shaped substrate tunnel, (ii) mixed and active-site-adjacent inhibitors that engage surface pockets flanking the catalytic site, (iii) allosteric and hybrid modulators that bind to regulatory regions distinct from the active site, and (iv) functionally validated PAD4 binders supported by biophysical and cellular evidence. Integration of structural, biochemical, and cellular data highlights that indirect or noncanonical modes of PAD4 regulation represent biologically coherent strategies for controlling pathological NETosis. Full article

The large-scale accumulation of titanium-extraction tailing slag (TS) poses environmental concerns, while its application is constrained by high impurity contents and low hydraulic reactivity, which is further exacerbated by the necessary dechlorination process. This study aims to evaluate the effectiveness of synthetic calcium silicate hydrate (C-S-H) nanocrystals in improving the performance of cement pastes incorporating deeply dechlorinated TS (DD-TS). To ensure uniform dispersion and activity, C-S-H seeds with varying crystallinities (55–94%) were prepared via a dynamic hydrothermal method (180 °C for 1–3 h) and incorporated into the composite binder in a wet-powder form at dosages of 0.5–2.0%. Results indicate that C-S-H-1, with the lowest crystallinity, offered the highest efficiency. At 1.5% dosage, the 1 d compressive strength increased by 64.6% to 18.6 MPa, while the initial setting time decreased by approximately 40%. Microstructural analyses reveal that poorly crystalline C-S-H provides abundant nucleation sites, accelerating early hydration and densifying the matrix to levels comparable to 7 d control pastes. These findings demonstrate the potential of C-S-H seeding for enhancing the utilization of DD-TS in cement-based materials. Full article

This study aims to systematically synthesize and critically evaluate the characteristics of electric arc furnace slag (EAFS) and ladle furnace slag (LFS) when applied as an alternative paving material. A systematic literature review was conducted following the PRISMA methodology, with research published between 2000 and 2024. Three major databases were searched, considering only Q1–Q2 and English articles. After independent, blinded screening by two reviewers, a total of 177 papers met the selection criteria. The results were qualitatively synthesized through bibliometric analysis, slag characteristics, and application type. Results show that asphalt concrete (AC) is the most common application of EAFS, representing 61% of studies, with many studies exploring 100% substitution of natural aggregates. Overall, EAFS and LFS demonstrate favorable mechanical properties, including high toughness, hardness, and adequate soundness, largely attributed to their iron-rich composition, supporting their use in base layers, AC, and Portland cement concrete (PCC). However, significant chemical and mineralogical variability influences swelling potential and reactivity, highlighting the need for case-specific characterization. While swelling concerns limit its use as an unbound base material, these issues are reduced when EAFS and LFS are used as a soil binder or encapsulated within AC or PCC matrices. Environmental assessments show that most EAFS and LFS samples meet the regulatory thresholds for their respective local leaching limits, though behavior varies with steel type (low-alloy vs. stainless), particle size and pH. Significant gaps remain in long-term performance and testing standards. This review proposes guidelines for selecting appropriate tests according to the intended pavement application, aiming to facilitate the safe and effective use of EAFS and LFS in road infrastructure. Full article