In the context of the mounting crisis of waste management and environmental sustainability, coal bottom ash (CBA) emerges as a pioneering solution in the field of construction. This study, which is a pioneering investigation, delves into the transformative impact of integrating CBA into the fabric of various concrete compositions, which range from traditional mortar to avant-garde geopolymer concrete. A comprehensive evaluation of mechanical properties, including compressive strength, flexural strength, and modulus of elasticity, is conducted alongside a spectrum of durability indicators such as water absorption, chloride ion resistance, and sulfate fortitude. Benchmarks set by global standards such as ASTM and EN serve as our yardstick, revealing that a strategic substitution of up to 10% of sand with CBA not only aligns with these rigorous norms but occasionally surpasses them. For cement, concrete, and geopolymer, the optimal replacement levels of CBA are between 10 and 30%. This enhances mechanical properties and promotes environmental sustainability. Our findings demonstrate the dual benefits of CBA: enhancing the structural integrity and durability of concrete while promoting ecological stewardship. This study not only validates the suitability of CBA as a superior construction material but also encourages the construction industry to pursue a more sustainable and waste-minimizing future.

This paper examines the compressive, flexural and tensile strength, ultrasonic pulse velocity, unit weight, water absorption, freeze-thawing, thermal and abrasion resistance, and microstructural properties of Interlocking Concrete Block Paving (ICBP) containing major industrial and agricultural wastes along with an assessment of their environmental effects, with a specific focus on recent work. The color, shape, and patterns of the blocks, their advantages, and their relationship with sustainability are discussed in this study. In addition, a limited number of studies that investigated the use of other byproducts are presented. Based on a review of the existing studies in the literature, recommendations are made for future studies. It has been determined that up to 30% inclusion of waste evaluated in ICBP provides optimal performance in terms of the evaluated properties. Moreover, as ICBP provides opportunities for low-energy concrete block production, the environmental burden and total cost of concrete and concrete block pavements can be reduced. Considering these benefits, studies performed on this subject seem promising. However, one of the missing points in ICBP is that the surface layer is not homogeneous due to the presence of various material types due to the coating design and analysis method. Therefore, modified slab analysis, layered elastic analysis, and finite element analysis can be used to analyze ICBP in detail.

This paper presents the microwave curing method as an alternative to conventional thermal curing of hybrid (fly ash-slag) geopolymer mortars (GMs) to achieve comparable performance with significantly reduced curing times. This study aimed to ascertain the impact of varying nano-silica contents (0.5%, 0.75%, and 1%) on the geopolymer matrix to identify the optimal dosage for enhancing densification and bond improvement phases. Mixture proportions were designed to achieve high mechanical and durability performances. The activator/binder (A/B) ratio was set at 0.71, the sodium silicate to sodium hydroxide ratio at 1.5, and the sand/binder (S/B) ratio at 2.5. This study considered two curing methods: thermal curing at 80 °C for 24 hours and microwave curing at 119 W for 3 minutes. The latter method produces equivalent thermal effects in a significantly shorter time. Physical properties tested after seven days included water absorption, porosity, and mechanical properties related to compressive and flexural strength. The results demonstrated that incorporating NS markedly enhanced the physical and mechanical characteristics. Moreover, microwave curing has been identified as a promising approach for producing hybrid geopolymers, offering a low-energy and high-performance alternative.