Evaluating the Performance of Low-Carbon Mortars for Sustainable Construction

The use of Recycled Fine Aggregate (RFA) combined with limestone calcined clay cement (LC³) shows a potential to reduce the environmental impacts of the ordinary Portland cement (OPC) production process, while also providing a viable alternative to the depletion of natural resources for building materials. This study was carried out to examine the mechanical and physical properties of LC³–based mortar integrated with high dosages of recycled fine aggregates. An affordable, eco-friendly, and sustainable alternative binder has been prepared by substituting 50 wt% of the clinker in CEM I with a blend of calcined clay (CC) and limestone (LS) powder with CC:LS of 2:1 in mass. The mortar was produced with RFA from construction and demolition waste as a substitute for natural sand with different replacement ratios of 50 vol% and 100 vol%. The fresh state behaviour of mortars was evaluated by the flow table test. The 28-days mechanical properties (compressive strength) were evaluated, and similarly, water absorption, capillary water absorption rate, and porosity were investigated after 28 days of curing for the durability assessment. The LC³ binder showed better mechanical strength than CEM II at all levels of fine aggregate replacement and improved the 28-days compressive strength by 12% for natural sand, 9% for 50% RFA, and 23% for 100% RFA, respectively. Similarly, the LC³ binder compensates negative impact of recycled sand porosity and reduces the capillary water absorption coefficient by 39, 47, and 42% for natural sand, 50%, and 100% RFA respectively. Employment of LC³ binder with RFA for the production of mortar with superior mechanical properties is useful for the reduction of environmental depletion and waste management.