Mechanical and microstructural properties of structural and non-structural lightweight foamed concrete with coal bottom ash as cement and sand replacement material

Abstract

This study aims to assess the feasibility of including coal-bottom ash (CBA) as a substitute for cement and fine aggregate, with a replacement ratio of 20%, and 75%, respectively, in the production of lightweight foamed concrete (LWFC) at two different densities: 1300 kg/m3 and 1700 kg/m3. The study provided data on both its fresh and hardened states. These include water absorption, density, compressive, splitting tensile strength, rupture modules, modulus of elasticity, X-ray Diffraction, and Field Emission Scanning Electron Microscope. The findings indicated that including CBA as a substitute for cement and fine aggregate can yield environmentally friendly foamed concrete suitable for structural applications, exhibiting a compressive strength of up to 25.5 MPa. In addition, decreasing the CBA aggregate size in specimens with a density of 1300 kg/m3 resulted in increased strength. The mixes that included CBA contained additional C-S-H gels, which led to a more compact structure.