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The World Bank study predicts that 4 °C warming will bring high temperatures, sea-level rise, and saltwater intrusion to coastal areas, damaging coastal concrete structures. Increased CO2 from industrialization exacerbates this, necessitating durable, low-carbon concrete. Combined use of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as high-volume OPC replacements boosts performance while reducing concrete's carbon footprint. In this perspective current study examines the durability of concrete against aggressive agents (H2SO4, MgSO4, NaCl, and CO2) causing premature deterioration of concrete structures. Initially, three cost-effective sustainable concrete mix designs were developed, incorporating 50% replacement of OPC with locally available supplementary cementitious materials, specifically FA and GGBFS. These mixes were then evaluated for their mechanical and durability performances. The impact of aggressive ions (SO42−, Cl−, and CO32−) was studied by examining the changes in mechanical performance and phase assemblages. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques were used to estimate the phase compositions. Ternary blended concrete having 50% OPC+ 30% GGBFS + 20% FA exhibited optimal synergistic performance, enhancing pozzolanic and hydraulic reactions for better resistance to harmful ions. The sorptivity test confirmed that as the GGBFS content increased, the sorption rate decreased, indicating the higher reactive nature of GGBFS to that of FA. Deleterious compounds formed due to the action of SO42-, Cl-, and CO32- were identified to be ettringite (Ca6Al2(SO4)3(OH)12.32H2O, AFt) and gypsum (CaSO4.2H2O, Gy), Friedel's salt (Ca4Al2(OH)12Cl2.4H2O, Fs) and polymorphs of calcium carbonate (CaCO3), respectively through TG mass loss curve. These results were corroborated by FTIR analysis, which showed predominant characteristic bands at 662 cm−1 for SO42−, 459 cm−1 for Mg–O stretching, 790 cm−1 for Al–OH bending, and 1431-1443 cm−1 for C–O, confirming the presence of the deleterious compounds. [ABSTRACT FROM AUTHOR]

This review paper provides a comprehensive analysis of radiation shielding concrete, covering its properties, design, evaluation, and applications. It begins with an introduction, stating the objective and scope. The paper explores radiation shielding basics, including ionizing radiation, shielding principles, and materials used for shielding. Concrete's properties relevant to shielding, radiation attenuation mechanisms, and factors affecting its efficiency are discussed. Different types of radiation shielding concrete are examined, along with their applications. The design and formulation of shielding concrete, including mix proportions, optimization techniques, and quality control, are presented. Evaluation methods and standards are discussed. Lastly, challenges, future directions, and emerging technologies are outlined. This review paper serves as a valuable resource for professionals involved in radiation shielding. The review on radiation shielding concrete highlighted its effectiveness in attenuating ionizing radiation, emphasizing material composition, density, and thickness as key design factors. Evaluation methods, such as gamma spectroscopy and Monte Carlo simulations, are discussed, demonstrating its versatile applications in nuclear facilities, healthcare, and space exploration. [ABSTRACT FROM AUTHOR]

Engineered cementitious composites (ECCs) have garnered significant attention within the construction industry, owing to their exceptional mechanical properties and durability. This thorough review presents a meticulous analysis of the progress and prospects in ECC research. It begins by introducing the background and rationale for investigating ECCs, while outlining the objectives of the review. The review provides an encompassing overview of ECCs, encompassing their definition, characteristics, historical development, composition and constituent materials. Emphasis is placed on the examination of ECCs' mechanical properties, specifically their flexural behaviour, tensile behaviour, compressive strength and resistance to environmental factors. Furthermore, the rheological properties of ECCs, including workability, flowability, self-healing, crack mitigation, viscosity and thixotropy, are discussed in detail. The review delves into the influence of fibre reinforcement on ECCs, encompassing the types of fibres utilised and their impact on mechanical and structural properties, as well as fibre dispersion and orientation. Additionally, it explores the diverse applications of ECCs across various fields, such as structural applications and sustainable building practices. The challenges and limitations associated with ECCs, such as cost and availability, are addressed, alongside an exploration of future trends and research directions. [ABSTRACT FROM AUTHOR]

This research aims to examine the effects of multistage processing on reducing the old cement fractions and enhancing the quality of concrete recycled aggregate (CRA). The investigation involves the use of demolished concrete debris and subsequent treatments in both single and multistage processes. The recycled aggregates (RAs) were obtained using a multistage jaw crushing process followed by utilizing natural aggregate, untreated RA, RA treated with hydrochloric acid (HCl) and sodium silicate (SS) immersion (single-stage treatment), and RA treated with mechanical scrubbing and SS immersion in two separate stages (multistage treatment). The subsequent phase of the experimental inquiry involves assessing the physical attributes of both treated and untreated RA. This is followed by conducting microstructural examinations utilizing techniques such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and thermogravimetry-differential thermal analysis. The findings indicate that employing a two-step process, involving mechanical abrasion followed by immersion in SS, yields high-quality CRA. This conclusion is reinforced by the favorable physical performance observed. The water absorption values of CRA were lowered by 78 % through single-stage treatments such as immersion in HCl. The similar treatment is found to show densest concrete with calcium/silicon ratio reduced to around 81 % to that of untreated CRA. Additionally, for single-stage treated CRA samples, microstructural study using FTIR verified the creation of additional hydration products, whereas for two-stage treated CRA specimens, thermogravimetric analysis demonstrated the formation of stable CSH. According to the findings, it is advised to use a multistage process of jaw crushing, then treating it with mechanical abrasion and SS. This has the ability to improve the physical, chemical, and microstructural properties of CRA. [ABSTRACT FROM AUTHOR]

A comprehensive overview of fracture propagation in concrete, covering various aspects ranging from fundamentals to applications and future directions, is presented. The introduction presents an overview of fracture propagation in concrete, emphasising its importance in understanding the behaviour of concrete structures. The fundamentals of fracture propagation are then explored, including concrete as a composite material, crack initiation and propagation mechanisms, types of fractures and the factors that influence fracture propagation. Next, experimental techniques for studying fracture propagation are discussed, encompassing both destructive and non-destructive testing methods, such as acoustic emission, ultrasonic testing, digital image correlation and advanced imaging techniques like X-ray computed tomography and scanning electron microscopy. Modelling approaches, including continuum damage mechanics, the finite-element method, the discrete-element method, the lattice discrete particle model and hybrid models, for simulating and predicting fracture propagation behaviour are then reviewed. The applications of fracture propagation in concrete are highlighted, including structural health monitoring, design optimisation, failure analysis and repair and rehabilitation strategies. Research opportunities for further improvement are addressed. This article should serve as a valuable resource for researchers, engineers and professionals in the field, providing a comprehensive understanding of fracture propagation in concrete and guiding future research endeavours. [ABSTRACT FROM AUTHOR]