Assessing the mechanical, durability, thermal and microstructural properties of sea shell ash based lightweight foamed concrete

The comprehensive properties of waste seashell ash (Oyster shell ash (OSA), Scallop shell ash (SSA), and Mussel shell ash (MSA)) in lightweight foamed concrete (LFC) are needed to explore for using these aquaculture wastes in light-weight building structures. Therefore, this study's aim is to investigate the fresh, transport, mechanical, pore structure, and thermal properties of OSA, SSA and MSA-based LFC. The seven LFC mixes have been prepared to evaluate the effect of 5, 10, 15, 20, 25, and 30% cement replacement by seashell ash and compared with the control mix. The test findings show that mixes' initial and final setting times increase with the seashell ash substitutions; however, the spreadability and density properties of the fresh test decrease. The MSA ash-based LFC exhibits 0.29-1% lower water absorption than the OSA and SSA ash-based specimens. It was further observed that the 15% MSA replacement in LFC exhibited a maximum of 12.41%, 15.89% and 17.95% enhancement in compressive, flexural and splitting tensile strength compared to the reference mix. Moreover, SEM assessment and pores distribution indicated that up to 15% replacement, the seashell as-based concrete performed better as a pore filler than the rest of the substitutions. The thermal conductivity and specific heat capacity exhibited better performance for all sea shell-based specimens; however, a 15% replacement of MSA seashell-based concrete can be the optimum solution for eco-friendly concrete production considering the overall assessment.