Performance improvement of waste oyster-shell powder–cement binary system via carbonation curing

The dumping of significant amounts of industrial waste oyster shells causes marine pollution and economic loss. Grinding and processing waste oyster shells into oyster shell powder (OSP) to substitute a portion of cement can potentially reduce marine pollution and greenhouse gas emissions. Herein, 0, 15, and 30% OSP were added to cement and cured by employing different methods with and without CO2. The dilution effect of the OSP reduced the heat of hydration. The compressive strength and electrical resistivity of all the mixtures increased after carbonation curing compared to the seal cured specimens. The CO2 absorption contents and rate of carbonation increased with an increase in the OSP content. During carbonation curing, OSP contributes to the carbonation of the cement material, forming large amounts of carbonation products (calcite, aragonite, and vaterite). The precipitation of carbonation products acts as a pore filler, significantly increasing the mixture's performance more than seal curing. Therefore, OSP has significant potential as a replacement material for cement via carbonation curing, and its promising CO2 capture and storage capacities provide a viable solution for greenhouse gas reduction.