Strength and Microstructure of Geopolymer Based on Fly Ash and Metakaolin

The production of Portland cement is widely regarded as a major source of greenhouse gas emissions. This contributes to 6–7% of total CO₂ emissions, according to the International Energy Agency. As a result, several efforts have been made in recent decades to limit or eliminate the usage of Portland cement in concrete. Geopolymer has garnered a lot of attention among the numerous alternatives due to its early compressive strength, low permeability, high chemical resistance, and great fire-resistant behaviour. This study looks at the strength and microstructure of geopolymer based on fly ash and a combination of metakaolin and fly ash. Compressive strengths were measured at 7, 14, and 28 days, and microstructure was examined using SEM and XRD

Molecular dynamics simulation in concrete research: A systematic review of techniques, models and future directions

This paper presents a comprehensive review of the application of molecular dynamics simulation in concrete research. The study addresses the background and significance of the topic, providing an overview of the principles, applications, and types of molecular dynamics simulation, with a particular focus on its role in enhancing the understanding of concrete properties. Moreover, it critically examines existing research studies that employ molecular dynamics simulation in concrete research, highlighting the associated benefits and limitations. The paper further investigates various simulation techniques and models employed in concrete research, offering a comparative analysis of their effectiveness. Additionally, the study explores future directions and identifies research needs in the field of molecular dynamics simulation in concrete, while also discussing the potential impact of this approach on the sustainability of the construction industry. By providing a comprehensive overview and critical analysis, this review serves as a valuable resource for researchers and practitioners interested in leveraging molecular dynamics simulation for advancing concrete science and engineering

Adaptation to the Future Climate: A Low Carbon Building Design Challenge

In this paper an attempt has been made to assess the performance of an office building located in London (one of the case study buildings in CIBSE TM36: 2005) in relation to energy consumption, carbon emissions and potential for adaptability to the 2050s climate. Overheating is a particular issue in office buildings due to internal heat gains from computers and other electrical equipment. In addition, buildings in London are affected by the urban heat island, which is likely to intensify with warmer summer temperatures, reducing the capacity for night-time cooling of buildings. This paper proposes various passive design strategies which aim to address both mitigation (by reducing carbon emissions) and adaptation (by improving human comfort and reducing energy consumption)

Life Cycle Assessment of construction materials: Methodologies, applications and future directions for sustainable decision-making

This review paper presents a comprehensive analysis of Life Cycle Assessment (LCA) methodologies applied to construction materials. It begins with an introduction highlighting the significance of LCA in the construction industry, followed by an overview of LCA principles, phases and key parameters specific to construction materials. The methodological approaches utilised in LCA, including inventory analysis, impact assessment, normalisation, allocation methods and uncertainty analysis, are discussed in detail. The paper then provides a thorough review of LCA studies on various construction materials, such as cement, concrete, steel and wood, examining their life cycle stages and environmental considerations. The review also explores recent advances in LCA for construction materials, including circular economy principles, renewable alternatives, technological innovations and policy implications. The challenges and future directions in LCA implementation for construction materials are discussed, emphasising the need for data quality, standardisation, social aspects integration and industry-research collaboration. The provides valuable insights for researchers, policymakers and industry professionals to enhance sustainability in the construction sector through informed decision-making based on LCA

Water-soluble polymers in cementitious materials: A comprehensive review of roles, mechanisms and applications

This review paper provides an extensive assessment of the diverse roles played by water-soluble polymers in cementitious materials. It commences with an introduction that provides a thorough overview of the background, objectives and limitations of the review. Subsequently, the various types of water-soluble polymers, encompassing natural, semi-synthetic and synthetic variants, are examined in detail, alongside an exploration of their working mechanisms within cementitious materials. Mechanisms discussed include entanglement and association, adsorption and complexation, as well as bridging. Furthermore, this review delves into the influence of watersoluble polymers on the microstructure, fresh properties, mechanical properties and durability of cementitious materials. A comprehensive analysis of the challenges and opportunities associated with the implementation of water-soluble polymers in cementitious materials is also presented, followed by a summary of the key findings and recommendations for both practical applications and future research endeavors. Overall, this review provides invaluable insights for researchers and practitioners, shedding light on the multifaceted functions of water-soluble polymers in cementitious materials

A review of fracture propagation in concrete: fundamentals, experimental techniques, modelling and applications

This paper provides a comprehensive overview of fracture propagation in concrete, covering various aspects ranging from fundamentals to applications and future directions. The introduction section presents an overview of fracture propagation in concrete, emphasising its importance in understanding the behaviour of concrete structures. The fundamentals of fracture propagation are explored, including concrete as a composite material, crack initiation and propagation mechanisms, types of fractures and factors influencing fracture propagation. Experimental techniques for studying fracture propagation are discussed, encompassing both non-destructive and destructive testing methods, such as acoustic emission, ultrasonic testing, digital image correlation and advanced imaging techniques like X-ray tomography and scanning electron microscopy. Modelling approaches, including continuum damage mechanics, finite element method, discrete element method, lattice discrete particle model and hybrid modelling approaches, are reviewed for simulating and predicting fracture propagation behaviour. The applications of fracture propagation in concrete are highlighted, including structural health monitoring, design optimisation, failure analysis and repair and rehabilitation strategies. The research opportunities for further improvement are addressed. The paper serves 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

Thermal energy storage in concrete: A comprehensive review on fundamentals, technology and sustainability

This comprehensive review paper delves into the advancements and applications of thermal energy storage (TES) in concrete. It covers the fundamental concepts of TES, delving into various storage systems, advantages, and challenges associated with the technology. The paper extensively explores the potential of concrete as a medium for thermal energy storage, analysing its properties and different storage methods. Additionally, it sheds light on the latest developments in concrete technology specifically geared towards thermal energy storage. The evaluation section discusses measurement techniques, experimental evaluations and performance metrics. Environmental and economic aspects, including sustainability and cost analysis, are thoughtfully addressed. The review concludes by underlining the significance of thermal energy storage in concrete, emphasizing its role in efficient energy management and the promotion of sustainable practices

Roadmap to a net-zero carbon cement sector: Strategies, innovations and policy imperatives

The cement industry plays a significant role in global carbon emissions, underscoring the urgent need for measures to transition it toward a net-zero carbon footprint. This paper presents a detailed plan to this end, examining the current state of the cement sector, its carbon output, and the imperative for emission reduction. It delves into various low-CO2 technologies and emerging innovations such as alkali-activated cements, calcium looping, electrification, and bio-inspired materials. Economic and policy factors, including cost assessments and governmental regulations, are considered alongside challenges and potential solutions. Concluding with future prospects, the paper offers recommendations for policymakers, industry players, and researchers, highlighting the roadmap's critical role in achieving a carbon-neutral cement sector

Combined Effect of Multistage Processing and Treatment Methods on the Physical, Chemical, and Microstructure Properties of Recycled Concrete Aggregates

This research aims to examine the effects of multi-stage processing on reducing the old cement fractions and enhancing the quality of CRA (concrete recycled aggregate). The investigation involves the use of demolished concrete debris and subsequent treatments in both single and multi-stage processes. The recycled aggregates (RA) were obtained using a multi-stage jaw crushing process followed by utilising natural aggregate, untreated RA, RA treated with hydrochloric acid and sodium silicate immersion (single stage treatment) and RA treated with mechanical scrubbing and sodium silicate immersion in two separate stages (multi-stage 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 utilising techniques such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry-differential thermal analysis (TG-DTA). The findings indicate that employing a two-step process, involving mechanical abrasion followed by immersion in sodium silicate, yields high-quality CRA. This conclusion is reinforced by the favourable physical performance observed. The water absorption values of CRA were lowered by 78% through single-stage treatments such as immersion in hydrochloric acid. The similar treatment is found to show densest concrete with Ca/Si 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 stages treated CRA specimens, TGA analysis demonstrated the formation of stable CSH. According to the findings, it is advised to use a multi-stage process of jaw crushing, then treating it with mechanical abrasion and sodium silicate. This has the ability to improve the physical, chemical, and microstructural properties of CRA