Combined effect of synthesized waterproofing and accelerating admixture on performance of ordinary Portland cement

Abstract The effect of a synthesized waterproofing and accelerating admixture on the properties of Ordinary Portland Cement (OPC) mortar cube was investigated, focusing on compressive strength, setting time, bulk density, apparent porosity, and water absorption. The study employed advanced characterization techniques such as FT-IR, XRF, XRD, TG/DTG, and DSC to analyze the chemical and structural changes within the cement matrix. It was demonstrated that the admixture significantly enhances compressive strength, with a 25% increase observed within the first three days of curing. Additionally, the admixture reduces setting time and apparent porosity while increasing bulk density and resistance to water absorption. The most effective concentration was found to be 2%, which provided optimal improvements in mechanical properties and durability. The results show a 25% increase in compressive strength after 3 days, a 35% increase after 7 days, and a 37% increase after 28 days with an optimized combined 2% admixture. XRD confirmed enhanced C–S–H formation and reduced portlandite at the optimal 2% admixture. TG/DTG and DSC results indicated increased bound water and accelerated hydration. These findings correlate with higher compressive strength, reduced porosity, and increased bulk density, confirming the admixture’s role in refining the microstructure and improving cement mortar performance.