Combined Metakaolin and Ground Granulated Blast-Furnace Slag-Induced Concrete for Marine Environment

Incorporating extra materials called admixtures is one of the major ways researchers have been using to produce concrete that can overcome adverse exposure conditions. In this light, this study experimented with the combined usage of Metakaolin (MK) and Ground Granulated Blast-furnace Slag (GGBS) by partially replacing cement at 40%, 50% and 60% and maintaining water to cementitious content (w/cm) at 0.45 to know to what extent can cement be replaced by this blend to give better durability performance without compromising the strength. The experimental program included tests on concrete durability properties such as water absorption, permeable void and sorptivity as well as compressive and flexural strength of concrete exposed to artificial saline water. This study found out that samples with 40% cement replacement by 30% GGBS and 10% MK performed better than other partial replacement levels in regards to compressive strength (31.56 MPa) and the overall durability properties investigated (5.73%, 16.86%, 0.0209, 0.00243 for water absorption, permeable void, primary sorptivity and secondary sorptivity, respectively). The samples with 60% cement replacement having 40% GGBS and 20% MK gave the best resistance to primary sorptivity (0.01801) but had the worst performance for compressive strength (16.14 MPa) in saline water. It is concluded that replacing cement by combining MK and GGBS can give satisfactory performance for durable concrete in Marine Environment, however, the partial replacement of cement should not be more than 40%. Incorporating GGBS and MK has environmental benefit as they are waste materials and their usage should be encouraged.