Abstract

The paper investigates the differences in the chemical composition of the selected Cem 1 cement brands in Kenya and their effect on mechanical properties of concrete. It also investigates if the differentiation in mechanical properties of concrete prepared from different cement brands affects its service life. Currently, there are nine cement manufacturers in Kenya, the majority of whom produce Cem 1 cement along with other grades. To achieve the desired objective, three cement brands; Cem A, Cem B and Cem C of Cem 1 were used in preparation of concrete samples for testing. Other concrete constituent materials; fine and coarse aggregates and steel were obtained from the local Kenyan market suppliers. The physical and chemical properties of the materials were investigated to ensure compliance with relevant applicable standards. Concrete of characteristic strength of 25N/mm2 derived from the DOE method was used. Concrete materials were batched by weight and mixed by a lab electric pan concrete mixer in batches of 0.009 m3 . The concrete batches were tested for consistency by the slump and compaction factor tests. For each brand of cement 9 cubes of 150mmx 150mm x 150mm for compression test, 9 cylinders of 150mm x 300mm for tensile strength were cast. After 24 hours the cast specimens were demolded and immersed in curing tanks for 27 days. Specimens for compression and tensile test were tested at 7,14 and 28 days. From the results in the research, the different Kenyan selected cement brands affect the compressive strength which influences the rate of infiltration of corrosion agents affecting the service life of reinforced concrete. The variation in chemical composition must be taken into account when formulating the concrete mix design for specific structural purposes.

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