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.