Blast Furnace Slag and Rice Husk Ash as sustainable materials in ternary blended concrete

This study investigated creating a sustainable M25 grade ternary blended concrete by replacing Ordinary Portland Cement (OPC) with 30% Blast Furnace Slag (BFS) and different amounts (0%, 5%, 10%, and 15%) of Rice Husk Ash (RHA). The fresh and hardened properties (slump, compressive strength (CS), density, and water absorption (WA)) of these concrete mixes are evaluated to determine the best blend. Overall the results indicate that the blend that contains 30% BFS and 10% RHA (SR2) is the most optimum: it had an acceptable slump of 78 mm that gave it a reasonable workability and worked effectively with curial material properties; it had the highest 28-day CS of 36.5 MPa which surpassed the control mix (32 MPa) due to whole material effects of pozzolanic and filler synergy; it had a hardened density of 2220 kg/m3, which is moderate, a reasonable 5.13% decrease from the control; and it had a water absorption of 2.25% which indicated a manageable increase in porosity, balanced with high gains in strength. The control mix achieved a higher density and overall workability with less WA. However, mixes with greater (10–15%) RHA developed a lower density, lower workability and greater WA. The 10% RHA mix indicated the appropriate compromise between promoting better mechanical performance with acceptable durability, confirming to be a structurally appropriate and environmentally sustainable concrete mixture.