Optimization of ternary OPC mortar incorporating termite hill soil and thermoactivated recycled concrete cement

Abstract

The construction industry now faces significant environmental pressures, driven by cement production's high greenhouse gas output and the vast volumes of construction and demolition waste (CDW). Innovative strategies are emerging to manage materials sustainably and minimize waste. Notably, using recycled concrete as alternative binders-like Thermo-Activated Recycled Concrete Cement (TARC)-and incorporating Termite Hill Soil (THS) shows great promise. Hence, this study evaluates the synergistic effect of TARC and THS in ternary Ordinary Portland Cement (OPC) blends to further optimize the TARC-OPC mix and promote sustainability. The complementary properties of TARC and THS, such as improved pozzolanic reactivity and particle packing, are harnessed to enhance mechanical performance and durability. In this regard, a comprehensive set of material characterizations, performance assessments, and microstructural analyses were conducted. The ternary blend TATH10 (10% THS + 20% TARC) achieved the highest compressive strength at 28 days (31.50 MPa) and 56 days (38.50 MPa), outperforming the binary blend TATH0 (30% TARC + 0% THS), which recorded 26.43 MPa and 32.01 MPa, respectively. The combination also enhanced durability and refined the microstructure, confirming a clear synergistic effect. This investigation demonstrate the combined benefits of TARC and THS in OPC blends, offering a novel, sustainable approach to reducing cement emissions while improving mortar performance and supporting global sustainability goals.