Long-term mechanical and statistical characteristics of binary- and ternary-blended concrete containing rice husk ash, metakaolin and silica fume

An experimental study has been executed to examine long-term strength and durability characteristics of concrete mixes incorporating three types of supplementary cementitious materials (SCMs), namely rice husk ash (RHA); metakaolin (MK); and silica fume (SF) as substitution to cement content. These SCMs were mixed in binary- and/or ternary-blended form in the cement-bound composites having percentages of replacement in range between 5 and 10%. Seven different types of mixes were prepared and assessed for workability, compressive strength, splitting tensile strength and water absorption. For evaluating short- and long-term strengths, the concrete specimens were tested at curing age of 3, 7, 28, 56 and 180 days, whereas 28, 56 and 180 days of curing age were chosen to assess the water absorption value. Results revealed that considered SCMs decrease the strength of matrix up to 28 days of curing but aids in restoring it in later ages. For all mixes, experimental results indicate that the substitution of RHA and MK, or RHA and SF while altering cement content increases the composite potential in resisting higher loads in compression as well in tension, while on other side, degrades the water absorption capacity. A multivariable nonlinear regression model having higher order of accuracy has also been proposed for estimating compression strength, tension strengths and the water absorption capacity along with analysing cost and economic benefits of utilising SCM concrete.