Designation of a new strategy to produce high-strength calcium carbonate-raw bentonite-based mortar via the remineralization process under elevated temperatures

This study focused on the developement of an innovative calcium carbonate (CC)-raw bentonite (RB) mortar for high temperature purposes. The main strategy proposed in this work relies on the synergistic thermal and chemical activation of CC/RB-based mortar to produce a hardened material with optimal engineering properties. Instead of calcining RB before alkali-activation, thermochemical activation was applied to the CC/RB-based mortar to produce a thermally stable hardened material. This process resulted in the formation of stable minerals, such as wollastonite and gehlenite, alongside the formation of solidified melt at high temperatures, leading to the densification of the microstructure and the creation of a hardened material with higher performance and stability compared to cured samples. The hardened mortar with the highest compressive strength value (∼ 57 MPa) was obtained by adjusting the CC/RB weight ratio at 50 wt.% /50 wt.%, Na 2 O concentration of 7.5 wt.%, sand / waste glass (WG) aggregate weight ratio of 25 wt.%,/75 wt.%, and exposure temperature of 1000 °C. Surprisingly, the proposed strategy produced a hardened material with a considerable compressive strength of ∼ 23 MPa without adding Na 2 O. Accordingly, the proposed approach can resolve the economic and environmental shortcomings of using a chemical alkali-activator. • A new strategy was applied to produce high-strength mortar-based calcium carbonate. • The remineralization process was performed at a temperature higher than 800 °C. • The remineralization process includes the transformation of calcium carbonate and bentonite into ghelenite and wollastonite. • Waste glass provides the system with solidified melt with high mechanical properties. • The applied strategy can be used to produce solidified materials with no need for an alkali-activator.