The incorporation of locally available supplementary cementitious materials (SCMs) in cement blends is essential for reducing the environmental impact of construction. However, assessing the pozzolanic kinetics, and thus the pozzolanic contribution at a given age, is challenging due to temperature differences between the two main evaluation methods: ASTM C1897 (40 °C, continuous heat release) and ASTM

Superhydrophobic cementitious composites are potential candidates to effectively mitigate long-term performance deterioration of concrete buildings due to external water infiltration. However, traditional superhydrophobic modification leads to a significant reduction in compressive strength. To address this, a carbon sequestered superhydrophobic mortar with a water contact angle of 153°–162° and an

Current research on recycled concrete powder (RCP) influencing the cement-based material's rheology primarily focuses on the initial rheology, with limited attention given to long-term rheology (rest time over 60 min). This work investigates RCP influencing the paste's static yield stress evolving with time (10–120 min). Results show that RCP significantly influences the cement paste's static yield

MgO-based cement offers a promising solution to lower the carbon footprint compared to that of Portland cement, where MgO is sourced from fossil-free minerals. The hydration of MgO plays a key role in these cements. However, MgO required higher water demand to achieve a workable mix, which poses drawbacks in microstructure and strength development. In this work, we investigated the effects of 7 polycarboxylate-based

Polyvinyl alcohol (PVA) has shown potential in developing cost-effective anti-freezing technologies for concrete. However, its effectiveness in reducing scaling and performance stability under combined salt freeze-thaw conditions and the involved mechanism remains unclear. This investigation systematically evaluates the salt freeze-thaw resistance of cementitious systems modified with PVA variants

Understanding the chloride threshold value (CTV) under various environmental conditions is essential for condition assessment and service life estimation of reinforced concrete (RC) structures susceptible to corrosion damage. This study investigates the influence of three exposure temperatures (25 ˚C, 35 ˚C and 45 ˚C) on the passivation and depassivation (i.e., corrosion initiation) of steel bars in

In this study, the spatial and temporal evolution of mineralized steel slag compacts (MSSCs) in terms of mineral composition, microstructure, and micromechanical properties is systematically investigated to characterize and quantify their inhomogeneity. Furthermore, the impact of the inhomogeneity in MSSC on its mechanical behavior and damage mechanisms is explored to uncover the intrinsic connection

The construction methods of Engineered Cementitious Composites (ECC) are crucial for ensuring the structural performance of ECC pavements, which have demonstrated superior fatigue life and heavy traffic capacity. However, the commonly used rolling compacted (RC) method for pavement has never been explored for RC-ECC pavement. In this study, RC-ECC was developed via theoretical and experimental methods

As a promising sustainable alternative to ordinary Portland cement (OPC), there are still doubts about the protective properties of belitic calcium sulfoaluminate (BCSA) cement to the embedded steel, especially for its low pore solution alkalinity and high sulfate concentration. To guarantee the corrosion resistance of steel reinforcement in BCSA cement, using corrosion-resistant steels, such as stainless

Soda residue, a by-product of the Na2CO3 industry, is recognized for its high alkalinity, which can lead to corrosion and the deposition of iron oxide (Fe2O3) from industrial procedures and lab infrastructure. This study delves into the effects of incorporating Fe2O3-rich soda residue (FSR) into alkali-activated materials (AAMs), specifically alkali-activated fly ash (FA) and/or slag powder (SP), on

Engineered Cementitious Composites (ECC) are high-performance cementitious materials that exhibit multiple cracking and self-controlled width under uniaxial loading, which can lead to a low permeability. Quantifying the water flow behavior of an ECC crack is a precondition for its practical application. However, the lack of characterization for internal crack profiles and advanced modeling for water

Fly ash, a by-product of coal combustion, is a pozzolanic solid waste with annual production of 1.63 billion tonnes, which has been widely used to replace cement clinker to develop sustainable concrete. However, the incorporation of high volumes of inert fly ash significantly reduces the early mechanical strength of concrete due to its low pozzolanic activity. This study presents an innovative strategy

Matrix strength and interfacial bonding between aggregate and matrix are critical factors influencing the performance of lightweight cementitious composites (LCC). This study proposes an environmentally friendly and efficient strategy for developing high-performance fly ash cenospheres (FAC)-containing LCC by combining sodium sulfate (SS) and calcium-silicate-hydrate (C-S-H) seeds. Moreover, the roles

Limestone calcined clay cement (LC3), a low-carbon cementitious material, has demonstrated outstanding resistance to chloride ion penetration. However, the real environment is rich in many harmful ions beyond chloride ions, including sulfate and magnesium ions, making the interactions among these ions highly complex. This study systematically explores the impact of sulfate ions and the synergistic

The performance of low-carbon cements prepared from different neat calcined clays (CCs) can be very inconsistent due to substantial variations in the composition of the CC samples. To gain a better understanding and further promote the practical application of such low-carbon cements incorporating CCs, the influence of calcined clays possessing different mineralogical compositions on the rheological

The percolation threshold plays a significant role in influencing the yield stress of cement-based materials. However, this crucial parameter has not been well understood given the absence of robust and reliable experimental methods and computing models. This study estimates the percolation threshold through regression analysis of yield stress and reveals its physical implications from the microscopic

Alkali-activated aluminosilicates (AAA) are considered a potential environmentally friendly alternative to traditional concrete. Previous studies also showed their better high-temperature performance as compared with cement-based composites. In this paper, a comprehensive assessment of AAA's behavior at high temperatures is presented. A detailed analysis of physical and chemical processes taking place

Phosphogypsum (PG)-based cementitious materials often suffer from low strength and poor water resistance, especially when incorporating a high volume of PG. This issue arises mainly from the high solubility of CaSO4·2H2O. This study develops a novel CO2-assisted alkali activation method for phosphogypsum-based cementitious materials (HPCM), improving compressive strength to 49.3 MPa (+50.83 %) and

Bacteria-based self-healing concrete is promising in sustainable constructions, while the germination of carbonate precipitating bacterial spores in crack zone is the start of the healing process, and hence has great impact on crack healing efficiency. In this study, the Ca-alginate hydrogel sheets encapsulated spores were pre-embedded at specific crack depths, and the in-situ germination behavior

This study aimed to investigate the phase assemblages of Portland cement (PC) samples and eluate compositions for various water compositions and liquid/solid (L/S) ratios using thermodynamic equilibrium calculations. Specifically, diverse groundwater and seawater compositions were selected as eluates to represent practical leaching conditions. Samples made of PC with carbonation degrees of 0, 10, 20

Steel slag with high aluminum (Al) content significantly delays the early hydration of cement when used as a supplementary cementitious material (SCM). To address this challenge, this study investigates the effects of gypsum (Gy) and sodium sulfate (SS) additions on the performance of cement pastes with 30 % high-Al ladle metallurgy furnace (LMF) slag. The mechanical properties, hydration kinetics

The development of not-toxic retarders with a high retardation efficiency is crucial for a sustainable development of high-performance magnesium potassium phosphate (MKP) cement-based materials. Zinc acetate is such a promising new set retarder for MKP cements. The impact of zinc acetate on the properties and hydration of the MKP cements at a Mg/PO4 molar ratio of 8 was investigated up to 5 years.

The integration of ultra-high-performance concrete (UHPC) with 3D printing technology introduces the revolutionary potential, offering exceptional mechanical properties, enhanced design flexibility, and automated construction processes. However, without additional reinforcement, the fracture performance of 3D-printed UHPC (3DP-UHPC) becomes critical to the crack resistance structures. To address the

In order to improve the high temperature resistance of building materials and develop a material that does not need to be repaired after fire, this paper develops a novel high temperature resistant geopolymer with metakaolin-fly ash blended precursor and corundum aggregates, characterized by thermal enhanced ultra-high residual strength. The surface morphology, mass loss, volume shrinkage, compressive

Incorporating construction and demolition waste aggregate (DW) into concrete addresses environmental concerns by reducing the demand for virgin materials and diverting waste from landfills. However, the high porosity of DW negatively impacts the durability of concrete. In this work, DW was functionalized by impregnating it with paraffin to fill its inherent pores. Additionally, the phase change characteristics

To address the complexity of using multiple binders in a single system, the present study was designed as part of an initiative to blend commercially available Portland cement (PC) and calcium sulfoaluminate (CSA) clinker with supplementary cementitious materials (SCMs). Blast furnace slag and limestone or gypsum were selected as the SCMs in the experimental program to study the compound effect of

The post-heating flexural performance of carbon fiber-reinforced polymer (CFRP) bars after thermal exposure plays a critical role in determining whether concrete members should be demolished or strengthened. This study investigates post-heating flexural performance of a CFRP bar in ultra-high-performance fiber-reinforced concrete (UHPFRC) after thermal exposure. A total of six UHPFRC members were prepared

Alkali-activated materials offer a low-carbon and cost-effective approach for heavy metal immobilization. In this study, alkali-activated phosphorus slag (AA-PS) mixtures were designed to immobilize Cr(VI). This research integrates thermodynamic modelling and experiments to investigate the reaction processes, immobilization mechanisms, and leaching behaviors. The results show that the hydration products

This paper presents an approach to enhance the interlayer properties of 3D-printed concrete (3DPC) by synchronously spraying CO2-activated interface enhancer (CIE) onto the surface of printed concrete filament during the printing process, thus overcoming the inherent limitation of weak interlayer properties and unlocking new possibilities for automation construction. The CIE was developed by using

The real-time control of concrete's stiffening allows users to better control pumping and extrusion during 3D-printing processes. Here, a portlandite-based cementitious formulation (i.e., slurry or suspension) that features the potential for rapid CO2 uptake is adapted for 3D-printing applications. In particular, we showcase a portlandite-fly ash binder system combined with a thermoresponsive polymer

Elastic modulus is one of the key parameters of recycled concrete for its application as structural concrete. The effect of recycled coarse aggregate characteristics on concrete elastic modulus needs to be clarified to enhance concrete performance. This study investigated the effect of the properties of recycled coarse aggregate, new mortar, and interfacial transition zone (ITZ) on concrete elastic

The aggregate distribution in concrete significantly influences the location of Interfacial Transition Zones (ITZs), impacting the initiation and propagation paths of cracks and complicating the prediction of concrete's cracking behavior. To figure out the effects of aggregate distribution on concrete crack features, this study constructs a porosity-based heterogeneous model using the Discrete Element

With the growing interest in utilizing metallurgical slag for mineral carbonation, there is an urgent need to explore the application of flue gas-carbonated slag. This study investigated the microstructure of steel slag powder (SSP) carbonated under 10 % CO2 concentration and its impact on the hydration, rheological behavior and compressive strength of cement pastes. The primary carbonation products

Cement clinker production is a major contributor to CO2-intensive emissions and high energy consumption in the cement industry, necessitating urgent development of sustainable alternatives. In this study, thus, a CO2-activation recycled cement paste powder (ca-RCPP) with pozzolanic activity and aragonite whisker was synthesized by enhancing recycled cement paste powder (RCPP) through CO2. Meantime

Galvanized steel can be passivated in ordinary Portland cement (OPC) due to the formation of a protective calcium hydroxyzincate (CHZ) layer. However, it is rarely concerned about the corrosion resistance of galvanized steel in alkali-activated fly ash (AAFA). Accordingly, this study evaluated the passivation performance and chloride-induced corrosion behavior of galvanized steel in OPC and AAFA mortars

This study investigated the self-healing capability of two fibre reinforced cementitious mortars, with and without crystalline admixture, which were specifically developed for 3D concrete printing. Four-point bending tests were carried out to assess the recovery of mechanical properties, focusing on resistance and stiffness recovery indexes. Two residual crack opening displacements of 50 μm and 500 μm

A clinker-free, one-part alkali-activated materials (AAM) using calcined marine clay (CMC) and Ca(OH)2 (CH) was developed in this study. The influence of mechanical activation on the mechanical properties, morphology, and the microstructure of one-part AAM was explored. Chemical dissolution test elucidates the relationship between reacted SiO2/Al2O3 content, CH content, and pH values throughout the

Using chemically foamed geopolymers in 3D-printed building applications offers multifunctionality to the construction sector and enhances environmental sustainability; however, this topic remains virtually unexplored. To this end, the first part of this paper focuses on the fundamental stabilisation mechanism of chemically foamed geopolymers. In the second part, the most promising compositions were

The environmental impact of Portland cement production has intensified the search for alternative low-carbon cement. Reactive magnesium oxide cement has emerged as a promising option. The current study investigates the hydration behavior, strength development, and phase evolution of MgO and MgO-RHA blends cured under sealed and carbonation conditions. Two RHA sources with differing amorphous content

X-ray computed tomography (CT) is a valuable tool for investigating the microstructure of concrete. This study introduces a method for analyzing the pore structures and microcracks of self-healing concrete after 300 rapid freeze/thaw (F/T) cycles using CT images with a relatively low resolution of 18.08 μm. Urea-formaldehyde microcapsules alone and in combination with polyvinyl alcohol microfibers

Fiber-reinforced cementitious composites (FRCC) exhibit enhanced mechanical properties when fibers are uniformly dispersed and aligned parallel to the principal stress direction. This study introduces a novel fiber-ball vibration method to improve fiber orientation in FRCC. The fracture performance of FRCC prepared with this method was evaluated, and the fiber distribution within the matrix was analyzed

The European Unions goal of climate neutrality by 2050 and the associated switch in pig iron production from the CO2-intensive blast furnace process to the direct reduction process means that blast furnace slag is becoming increasingly scarce and will no longer be available in some regions in the foreseeable future. This applies to its use in classic cements as well as in alkali-activated binders.

During the sulfate attack process, the expansion of CaSO4 formation in dense cement matrix resulted in the mechanical deterioration of cementitious materials. In this research, a novel expansion-tolerant strategy was proposed to mitigate the expansion pressure by guiding the formation of CaSO4 within the preset pores introduced by superabsorbent polymers (SAPs). The experimental results showed that

The integration of energy storage capabilities into building materials represents a revolutionary advancement in sustainable energy solutions. This study introduces and explores a carbon-fiber-reinforced cementitious supercapacitor, marking a pioneering step in leveraging construction materials for dual structural and energy storage purposes. Employing geopolymer cement (GC) as a solid electrolyte

Limestone calcined clay cements (LC3) are a promising class of low-clinker cementitious binders. While LC3 concrete is typically formulated with a water-to-solid (w/s) ratio of 0.40 or higher, more recent research has explored using a low w/s ratio. Many advanced cementitious systems like ultra-high-performance concrete (UHPC) and engineered cementitious composites (ECC) require lower w/s for optimal

This study investigated mechanical properties, including the negative Poisson's ratio (NPR) effect and energy absorption capacity, of single-cell unit rotation rigid body (SCRR) structures fabricated using 3D-printed engineering cementitious composites (ECC). Printable ECC mixtures were optimised for extrudability, buildability, and workability, achieving a compressive strength exceeding 40 MPa, tensile

Water penetration is the leading cause of durability deterioration of cementitious materials, and the rapid in-situ visualization and quantification of water penetration process is important for evaluating water absorption behavior and durability of material. This study proposed a novel method to rapidly visualize and quantify the water penetration into cementitious materials using near-infrared hyperspectral

Portland Cement in the well construction provides zonal isolation, preventing unwanted fluid migration to shallow aquifers or the surface. Despite its widespread application for well sealing, the evolution of cement sheath stress state during curing is not well-known. The radial stress in the cement sheath is the key parameter behind the formation of microannuli, a continuous fracture-like feature

This study prepared a low-carbon and economical high-strength artificial aggregates (HSAs) using sulfur-aluminum-ferric cementitious materials (SAF), fluorine gypsum (FG), and gold tailings (GT). Furthermore, HSAs were used to prepare concrete by replacing gravel and sand. The results show that at 80% GT, 17% SAF, and 3% FG, HSA has a high cylinder compressive strength of up to 12.57 MPa, a loose bulk

Alkali-activated slag (AAS) mortar has substantial limitations owing to its autogenous shrinkage, which leads to crack formation, and the self-healing property presents a promising solution to maintain its integrity and durability. Based on this, the self-healing efficiency of AAS mortar under a stable alkaline environment was assessed, with exogenous calcium ions introduced via a Ca(OH)2 solution

The poor dispersion of nano-TiO2 adversely affects the photocatalytic performance of photocatalytic cementitious materials (PCMs). In this study, a supported composite photocatalyst TiO2/montmorillonite (TiO2/Mt) was employed to prepare PCMs, aiming to improve the dispersion behavior of nano-TiO2. The impact of TiO2/Mt on the photocatalytic and mechanical properties of cementitious materials was also

This paper studies the time dependence of corrosion resistance in belitic calcium sulfoaluminate (BCSA) cement concrete. BCSA is a hydraulic cement that sets rapidly and has a lower carbon footprint than portland cement (PC). Some studies suggest that BCSA concrete is highly susceptible to chloride-induced corrosion, but these claims are based on testing at 28 days. No later-age results have been reported

New low-carbon concrete materials and technologies are urgently needed to reduce CO2 emissions and achieve sustainable development in the cement industry. Hybrid alkaline cement (HAC) is a new cement-based material that combines the advantages of ordinary Portland cement and alkali-activated cement. This study introduces a solid CO2 mixing method and investigated its impact on the performance and sustainability

The flow resistance of modern high-workable concrete during pumping is usually considered linearly related to the flow rate, but some studies have found a non-linear relationship. An accurate assessment model of concrete flow resistance at different flow rates remains unclear. This study presents a methodology for calculating the boundary resistance of high-workable concrete based on other flow velocity

High strain rate loadings lead to fundamental modifications in the tensile stress-strain response of steel fiber-reinforced concrete (SFRC). These modifications include higher tensile strength and corresponding strain and fracture energy. This paper investigates the effect of strain rate on the tensile behavior of SFRC, covering ranges from quasi-static (10−6 to 10−1 s−1) to impact (10–50 s−1). For