Role of Bivalve Shell Powder as a Partial Replacement in Mortar: A Case Study from the Yadayanthittu Estuarian Meretrix casta shells

Bivalve shells are covered with a hard part which is made up of calcium carbonate (CaCO3). The bivalve shells  have wide applications among one is a partial replacement of mortar. In this study, Yadayanthittu estuarian Meretix casta shells have experimented for partial replacement in the mortar. A variety of experiments were conducted and the results are discussed in details. The estuarian M.casta (bivalve) shells chemical constituents were measured by XRF instrument. The analytical results demonstrate that the Meretrix casta shells having a loss on ignition (LOI) about 44.00%; the calcium oxide (CaO) occupy 54.47%, and the other reported oxides accumulated to 1.5287 %. For mortar replacement study,  a total of seven experiments (E1-E7) was performed with different combinations. The first combination (E1) without any replacement in mortar and the second (E2) with 12.5% of fly ash replacement and the remaining experiments (E3-E7) consist of  Meretrix casta shell powder (MCSP) with various proportions of 12.5%, 8.75%, 8.33%, along with fine aggregates. Each combination was mixed with water and casted separately. After 07 and 28 days of curing, they cubes were removed, dried and measured the compressive strength. The compressive strength results indicate that the E7 combination exhibits higher strength by 41.80 and 56.8 Pa respectively. This could be due to the C-S-H gel formation in the mortar. The lowest results are observed in E4 combination, with the compressive strength of 32.42 and 47.42 at the age 07 and 28 days. These experiments show not enough binding capacity may be due to inadequate C-S-H gel formation.