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Utilisation of unused industrial wastes and the need for rapid volumetric construction led to the evolution of sustainable prefabricated housing elements, particularly for urban slums. An agro-industrial by-product as raw material and waste expanded polystyrene beads as the insulation material are chosen to develop a lightweight prefabricated construction element. This bio-ash is used as a partial replacement, 20 and 10%, for fine aggregates to prepare concrete and a lightweight mix, respectively. A small-scale model of one-third scale is conceptualised according to standards. This model includes precast columns and beams as framed structure and prefab panels as walling and roofing elements. These elements are developed according to the desired mix proportions of the identified raw materials. The respective laboratory specimens are evaluated for physico-mechanical, durability and thermal properties. The developed walling end product is found to be 27% lighter, 8% stronger, 24% less water absorbent and 62% less conductive when compared with the properties of commercially available fly-ash brick. A solar photovoltaic panel embedded into the pitch roof of the model can provide 71% of its generated energy to necessary electrical appliances. The material properties are found to be satisfactory for its on-site application. Also, the model's erection is 20% faster than the conventional method. [ABSTRACT FROM AUTHOR]

Economic growth and rapid urbanization have resulted in the increase in demand for infrastructure development. To meet this ever increasing demand, conventional construction materials such as concrete are used, which requires an energy intensive process that in turn impacts the environment adversely. Ordinary Portland Cement, being the dominant binder in the industry, contributes around 8% of worldwide annual carbon emissions, and this is expected to reach around 20% by 2050. Population growth has resulted in the significant increase in agro-industrial waste generation during recent years. Inadequate waste management raises a number of environmental concerns. With the growing economy and rising living standards, global raw material consumption is expected to double by 2060. The reutilization of waste materials will aid in their management, while conserving the available resources. Alkali-activated materials (AAM) have recently been introduced as an eco-friendly alternative to conventional binders with fewer environmental impacts. AAM reduce the need for Ordinary Portland Cement (OPC) by substituting it with supplementary cementitious materials (SCM), and therefore, reducing the amount of subsequent carbon emissions. Alkali activation is a complex chemical process between the precursors (alumino-silicate materials) and their dissolution in the activators. Different materials react to alkali activators in different ways depending on their properties. The current study aims to provide a critical review of potential agro-industrial wastes on the fresh and hardened properties of alkali-activated concrete (AAC). To understand the design and development of AAC, influencing the parameters such as the molarity of NaOH, alkali activators, and the ratio of the activators have been discussed in detail. The curing regime and its effect on the behavior of alkali-activated concrete are mentioned. The different admixtures used to regulate the properties of AAC are highlighted. AAC exhibited optimized embodied energy, operational energy, life cycle cost, CO2 emission, and raw material consumption rates than the conventional concrete did. However, these results varied based on the precursors used in them. This paper focuses on the design and development of AAC, and it should be viewed as an important contribution towards the adoption of AAC in practical applications. The study presents the potential of AAM as a net zero binder in the making of sustainable concrete with enhanced properties. [ABSTRACT FROM AUTHOR]