New Materials, Compounds and Applications

This study evaluates the physico-chemical performance of Ordinary Portland Cement (OPC) when partially replaced with stone-cutting dust (SCD), limestone (LS) and natural pozzolana (NP), both individually and in ternary combinations. Blends were formulated with SCD and NP at 10-40% and LS at 5-20%, including optimized ternary mixtures. Tests focused on normal consistency, setting time and water sorptivity. Results showed that all supplementary cementitious materials (SCMs) increased normal consistency, from 28.0% in OPC to 35.0% at 40% substitution. Setting time was significantly extended in SCM-rich blends, with initial and final setting times reaching up to 250-260 minutes, compared to 100 and 180 minutes for OPC. This delay, especially in NP and SCD-rich mixtures, reflects reduced reactivity and higher water requirements. Water sorptivity improved in optimized ternary blends, with Mix H (10% SCD + 10% LS + 15% NP) showing the lowest sorptivity coefficient of 0.1666 g/cm²/hr^0.5, compared to 0.1908 for OPC. These findings demonstrate that carefully balanced combinations of NP, LS and SCD enhance workability, provide longer setting windows and reduce water ingress, leading to improved durability. The results support the use of locally available materials in Kenya as sustainable and cost-effective alternatives for blended cement production.