Fabrication of Energy-Efficient Carbonate-Based Cementitious Material Using Sodium Meta-Aluminate Activated Limestone Powder

Limestone powder (LP) and sodium meta-aluminate (SMA) were used to fabricate calcium carbonate-based cementitious material, as a solution to address the solid waste problem. The effects of SMA doses and curing conditions on the hydration properties and mechanical performance of paste were investigated. The results show that the 28-day unconfined compressive strength and flexural strength of the paste with an LP/SMA ratio of 2/1 were 49.7 and 15.9 MPa, respectively. The characterization by scanning electron microscopy, X-ray diffraction, and thermal gravimetry shows that the calcium aluminum carbonate hydroxide hydrate (CACHH) was the predominant hydrated product and had a dense layered double hydroxide structure (LDHs). The microbridge effect developed by LDHs significantly increases the flexural strength of the paste. Meanwhile, the developed paste exhibited an extremely low carbon emission and energy consumption. This study also reveals the mechanism of LP incorporated with SMA to form CACHH. Overall, this work provides an approach of high value-added utilization for LP as a binder without tedious operation, which could address carbon emission reduction and circular economy of LP.