The main objective of this thesis was to determine the optimal mixing ratio of concrete suitable for field placement in order to achieve early strength development, ensuring a minimum compressive strength of 21 MPa and a minimum flexural strength of 1.5 MPa after 5 days of curing. To achieve this, a Compressive set of tests was conducted to evaluate the performance of three concrete types: blast furnace slag cement (BFC), early strength Portland cement (EPC), and a blend of EPC and BFC in a ratio of 7:3 termed MBE.
All three concrete types successfully achieved the desired compressive strength of 21 MPa or higher and flexural strength of 1.5 MPa ratio or higher after 5 days of curing. Notably, BFC exhibited lower compressive strength than EPC and MBE during the initial 5 days but demonstrated higher compressive strength after 28 days. This observation can be attributed to the delayed hydration reaction resulting from the latent water hardness characteristic inherent in blast furnace slag cement.
In contrast, EPC exhibited significantly higher compressive strength than BFC and MBE during the first 5 days of curing. However, its compressive strength at 28 days was comparatively lower due to its early strength development characteristic. Moreover, for all three concrete types, the splitting tensile strength and flexural strength exhibited higher values in proportion to the compressive strength compared to the results predicted by the general formula within the initial 5-day curing period.
When considering the economic feasibility, it was found that EPC incurred a cost 10.4% higher than BFC, while MBE incurred a cost 6.3% higher than BFC. Taking into account the compressive strength, splitting tensile strength, flexural strength, and economic aspects, it can be concluded that the mixing ratio utilizing early strength Portland cement (EPC) proves to be the most suitable option for achieving early strength in concrete applications.