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This study investigates a sustainable coating method for modified expanded polystyrene (MEPS) beads to improve the thermal insulation of lightweight concrete intended for wall application. The method employed in this study is based on a novel coating technique that represents a significant advancement in modifying Expanded Polystyrene (EPS) beads for enhanced lightweight concrete. This study experimentally assessed the energy-saving capabilities of MEPS concrete in comparison to control groups of uncoated EPS beads and normal concrete by analysing early-stage temperature, thermal conductivity, specific heat capacity, heat flux, and thermal diffusivity. The thermal conductivity of MEPS concrete is approximately 40% lower than that of normal concrete, demonstrating its usefulness in enhancing insulation. The heat flux calculated for MEPS concrete is significantly reduced (approximately 35%), and it has a 20% lower specific heat capacity than ordinary concrete, indicating a reduction in energy transfer through the material and, thus, potential energy-efficiency benefits. Furthermore, the study discovered that all test objects have very low thermal diffusivity values (less than 0.5 × 10−6 m2/s), indicating a slower heat transport through the material. The sustainable coating method utilized fly ash-enhanced thermal efficiency and employed recycled materials, hence decreasing the environmental impact. MEPS concrete provides a practical option for creating sustainable and comfortable buildings through the promotion of energy-efficient wall construction. Concrete incorporating coated EPS can be a viable option for constructing walls where there is a need to balance structural integrity and adequate insulation.

The availability of some supplementary cementitious materials, especially fly ash, is of imminent concern in Europe due to the projected closure of several coal-fired power generation plants. Pure kaolinitic clays, which arguably have the potential to replace fly ash, are also scarce and expensive due to their use in other industrial applications. This paper examines the potential utilisation of low-grade kaolinitic clays for construction purposes. The clay sample was heat-treated at a temperature of 800 °C and evenly blended with Portland cement in substitutions of 10–30% by weight. The physical, chemical, mineralogical and mechanical characteristics of the blended calcined clay cement were determined. The Frattini test proved the pozzolanic potential of the calcined impure clay, as a plot of its CaO and OH− was found below the lime solubility curve. The 28 days compressive strengths trailed the reference cement by 5.1%, 12.3% and 21.7%, respectively, at all replacement levels. The optimum replacement level between the three blends was found to be 20 wt.%.