ABSTRACT

The role of concrete in construction industry for buildings and other structures is very important. Concrete composes of coarse aggregate, fine aggregate, binder and other admixtures. It is a versatile building material, hence its utilization is more than other construction materials. This has made researchers to continue to make more research on the constituents ofconcrete for improvement in the properties of concrete. One ofthe constituents of concrete is cement (binder), which has attracted continuity in research every time. The use of chemical activators to cement or cement paste (cement and water) has caught a lot of attention to the researchers and global world. The materials utilized as chemical activator in this research work is Nickel II Sulphate Hexahydrate, to find the potential in modifying one of the properties of concrete, which is the compressive strength.This experimental study presents the mix proportion of Nickel II Sulphate hexahydrate with Ordinary Portland Cement (OPC). The mix was prepared by adding 0, 1, 3, 6 and 9% Nickel II Sulphate hexahydrate of OPC in the concrete mix. The compressive strengths ofthe prepared concretes were determined on 3, 7, 14 and 28lb day of curing. The compression was a destructive method using compression machine in the laboratory. The samples were concrete cubes of 150mm X 150mm X 150mm by dimension. It was discovered from the research that 1% to 6% range in addition is the recommended value for compressive strength, with 3% as the optimum value, as seen that all the concrete samples exceeded the target strength of 48.25MPa for the mix proportion except 9% addition at 28th day of curing. The values are 62.5, 63.0, 59.8 and 39.0MPa for 1, 3, 6 and 9% respectively, while the value of control concrete cube (0% addition of Nickel II Sulphate hexahydrate) was 62.45MPa. It was also discovered that the early strength was very high, with values of 23.2, 23.73, 24.17, 22.94 and 22.75MPa for 0, 1, 3, 6 and 9% at day3 of curing , which means Nickel II Sulphate hexahydrate can act as accelerating agent of strength in concrete. The results ofthe research shows that Nickel II Sulphate hexahydrate can be utilized as chemical activator in accelerating the early strength of concrete. In addition, Nickel II Sulphate hexahydrate addition in concrete can be used to produce high strength concrete. Keywords: Nickel II Sulphate hexahydrate, Concrete, Compressive Strength, Chemical activator. Early Strength