International Concrete Abstracts Portal

Engineered cementitious composites (ECC) represent a significant innovation in construction materials due to their exceptional flexibility, tensile strength, and durability, surpassing traditional concrete. This review systematically examines the composition, mechanical behaviour, and real-world applications of ECC, with a focus on how fiber reinforcement, mineral additives, and micromechanical design improve its structural performance. The present study reports on the effects of various factors, including different types of mineral admixtures, aggregate sizes, fiber hybridization, and specimen dimensions. Key topics include ECC’s strain-hardening properties, its sustainability, and its capacity to resist crack development, making it ideal for high-performance infrastructure projects. Additionally, the review discusses recent advancements in ECC technology, such as hybrid fibre reinforcement and the material’s growing use in seismic structures. The paper also addresses the primary obstacles, including high initial costs and the absence of standardized specifications, while proposing future research paths aimed at optimizing ECC’s efficiency and economic viability.

This study investigates the impact of air-entraining admixtures (AEAs) on mortar performance, focusing on fresh-state and hardened-state properties critical to durability and engineering applications. Ten distinct mortar mixtures were analyzed, following guidelines established by the European Federation of National Associations Representing Producers and Applicators of Specialist Building Products for Concrete (EFNARC). AEAs were introduced at varying proportions (0.01 to 0.5% of cement weight) to evaluate their effects on intrinsic properties (density, void ratio, and water absorption), rheological parameters (plastic viscosity and yield stress), and mechanical characteristics (compressive strength, ultrasonic velocity, and modulus of elasticity). Regression models were developed and yielded high predictive accuracy, with R2 values exceeding 0.98. Notably, ultrasonic velocity and modulus of elasticity demonstrated strong correlations with intrinsic properties across all curing ages. Similarly, compressive strength showed significant associations with rheological parameters, highlighting the influence of air content and flow behavior on structural performance. These findings offer precise quantitative models for predicting mortar behavior and optimizing formulations for enhanced performance.

The weakness of concrete in tension can be mitigated by developing fiber-reinforced concrete (FRC) to induce pseudoductility. However, enhancing the intrinsic tensile strength of the matrix in FRC has received little attention. In this regard, nanofibers, which can improve the intrinsic tensile properties of the matrix, were used in conjunction with microfibers to enhance intrinsic tensile strength. Different volumes of nanofibers (0.0 to 0.6%) and microfibers (0.0 to 2.0%) were tested, and various fresh and hardened properties were analyzed. Test results show that the high-range water-reducing admixture dosage increased with both nanofiber and microfiber volume and that strength increased with microfiber volume, reaching an optimum point at a certain nanofiber dosage. Moreover, incorporating nanofibers and microfibers to develop multiscale FRC (MSFRC) significantly improved direct tensile strength and energy absorption. The synergy between nanofibers and microfibers was revealed both qualitatively and quantitatively, contributing to the advancement of FRC.

In this study, low-carbon ultra-high-performance concrete (UHPC) was designed by adding fly ash-based mineral admixtures (SD-FA). The improved Andreasen & Andersen model was used to obtain SD-FA, which was then used to replace part of UHPC cement, to achieve the effect of low-carbon emission reduction. The effects of the composition and dosage of cement-based materials, the water-cement ratio, the composition of sand, the steel fiber content, and the lime-sand ratio on the properties of UHPC were studied, and the design of the batches was optimized. On this basis, the performance changes were analyzed at the micro level. The results show that when the 1~3 grade fly ash content after screening treatment is quantitative, the densest stacking is theoretically reached. The SD-FA optimized design improves the bulk density of UHPC and realizes the dense microstructure of UHPC. Under the optimal mixing ratio, its processability is guaranteed and the mechanical properties are enhanced.

A comprehensive laboratory testing program, field-testing program, numerical analysis, and life-cycle cost analysis were conducted to evaluate the beneficial effects of incorporating shrinkage-reducing admixture (SRA), polymeric microfibers (PMFs), and optimized aggregate gradation (OAG) into internally cured concrete (ICC) mixtures for rigid pavement applications. Results from the laboratory program indicate that all the ICC mixtures outperformed the standard concrete (SC) mixture. All the ICC mixtures showed a decrease in drying shrinkage compared to the SC mixture. Based on the laboratory program, three ICC mixtures and one SC mixture were selected for the full-scale test and subjected to a heavy vehicle simulator for accelerated fatigue testing. Extensive testing and analysis have shown that ICC mixtures incorporating SRA, PMFs, and OAG can be beneficially used in pavement applications to achieve increased pavement life.