Development and standardization of sustainable dry mix mortars with supplementary cementitious materials

Eco-friendly mortars are produced by replacing Ordinary Portland Cement (OPC) partially with Fly Ash, Rice Husk Ash (RHA), Ground Granulated Blast Furnace Slag (GGBFS) etc. in different proportions. Additionally, dense impermeable mortar is produced by including these supplementary cementitious materials (SCM) resulting in much lesser chloride/carbonation ingress, with reduced risks of reinforcement corrosion. The improper mortar mix proportions with ill-followed w/c ratio leads to poor strength, unsightly cracks and other durability problems. This study presents experimental investigations, in Indian context, to explore the feasibility of developing dry mix mortars with SCM- GGBFS and fly ash in different proportions. The studies were limited to water cement ratio of 0.4 to 0.6. The strength parameters of dry mix mortar and its fluctuations have been investigated for different shelf lives of dry mixes. Studies show that standard consistency for composite cement is slightly greater than that of 100% OPC. The delayed pozzolanic activity results in prolonged initial and final setting periods with a minor reduction in compressive strength. The strength of dry mix composite cement mortar remains constant across its 15, 30, and 60-day shelf lives. Better structural integrity with fewer voids and an improved C-S–H gel distribution is confirmed by through FTIR and SEM analysis. The utilization of dry mix mortar has reduced cement consumption, incorporated the wastes and produced almost impermeable mortar with reduced ingress of moisture and subsequent corrosion. This will be financially viable due to mechanization by bulk and specific production at specialized facilities to ensure long term performance of structures.