| dc.description.abstract | In the past decade Kenya has experienced an increased demand of cement for construction of
infrastructure projects including the Mega standard gauge railway and the Lamu Port South Sudan-Ethiopia
Transport Corridor. The cement production and consumption increased from 154,781 tonnes per year in January
2005 to 564,000 tonnes per year in January 2017 an average of 22% increment per annum.
Attracted by this growth and to meet the demand, the existing manufacturers have expanded while new cement
manufacturers have ventured into the Kenyan market bringing the total number of manufacturers to six. Each of the
manufacturers produces his own brand of ordinary Portland cement with specific constituents but meeting the
requirements of the Kenya Bureau of Standards. The constituents of the brands of cement react differently when
mixed with other constituents of concrete resulting into varying hardened properties that affect corrosion.
In this research three brands of ordinary Portland cement in the Kenyan market: Cem A, Cem B and Cem C were
used to investigate their effect on the properties of concrete that affect the rate of corrosion.
The main objective of this research was to investigate the effect of using different Kenyan brands of ordinary
Portland cement of the same strength on the rate of corrosion. The physical and chemical properties of the materials
were investigated for compliance to applicable British and Kenyan standards. The DOE method was used to derive
the mix design for a design strength of 25N/mm2. Concrete materials were batched by weight and mixed by using a
lab electric pan concrete mixer in batches of 0.009 m3. For each brand of cement 9 cubes of 150mmx 150mm x
150mm for compression test, 9 cylinders of 150mm x 300mm for tensile strength and 9 cylinders of 150mm x
300mm for accelerated corrosion test were cast. After 24 hours the cast specimens were demoulded and immersed in
curing tanks for 28 days.
Specimens for compression and tensile test were tested at 7, 14 and 28 days while the specimens for impressed
corrosion were immersed in a 3.5% industrial sodium chloride solution under a voltage and current of 6V and 2A
respectively. The applied current and voltage were monitored on a biweekly basis until corrosion induced cracking
appeared on the concrete surface. The impressed corrosion specimens were monitored visually using a 1000x optical
magnification glass for onset of cracks and stopped when the crack width were approximately 0.1mm in width. The
duration to approximated width of crack were 107days, 115 days and 111 days for Cem A,Cem B and Cem C
respectively.From the results in the research, different Kenyan cement brands of the same compressive strength have
a significant effect on the rate of corrosion of reinforced concrete structures.
ention the abstract for the article. An abstract is a brief summary of a research article, thesis, review, conference
proceeding or any in-depth analysis of a particular subject or discipline, and is often used to help the reader quickly
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point-of-entry for any given scientific paper or patent application. | en_US |
