Determination of Appropriate Mix Proportions for the Kenyan Blended Portland Cement Concrete Production
The Kenya’s vision 2030 seeks to address the rising needs of its population through infrastructure development. Reinforced concrete being the most commonly used construction material forms an integral part of this development strategy. The direct substitution of the ordinary Portland cements with the cheaper, lower strength, locally available blended Portland cements could be responsible for the production of poor quality concrete and contribute to the failure of several concrete buildings in the country. This paper presents findings of an experimental investigation on the appropriate mix proportions for the Kenyan blended Portland cement concrete. Key variables used in this study included the water/ cement ratio (x1), the cement/ total aggregates ratio (x2) and the fine aggregates/ coarse aggregates ratio (x3). The response was measured in terms of slump, compressive strengths at 7days, 14days and 28 days and density. Minitab 17 software was used in the design of experiments and results analysis based on Central Composite Design method. The investigation revealed that for a workable concrete with slump of ≥ 30mm, the appropriate mix ratios for the Kenyan blended Portland cement concrete are: 1:2.2:3.4 (w/c 0.6) for strength class C15 and 1:1.3:2.2 (w/c 0.5) for strength class C20. It was further noted that the different brands of blended Portland cement in the country had varying properties and thus produced concrete with different wet and hardened properties. None of the brands achieved the target design strength for strength class C25 and above. Therefore, the blended Portland cements may not be suitable for producing structural concrete strength class C 25 and above.
Government of Kenya, Kenya Vision 2030; A Globally Competitive and Prosperous Kenya, Government printer, Nairobi: Ministry of Planning and National Economic and Social Council (NESC), 2007.
K. K. Adewole, W. O. Ajagbe, & I. A. Arasi, “Determination of appropriate mix ratios for concrete grades using Nigerian cements”, Leonardo Electronic Journal of Practices and Technologies, Vol. 26, pp. 79-88, 2015.
V. A. Okumu, W. O. Oyawa & S. M. Shitote, “The Effect of the Properties of Constituent Materials on the Quality of Concrete in Kenya”, Proceedings of the 2016 Annual Conference on Sustainable Research and Innovation (SRI), 4th- 6th May, 2016. Nairobi, Kenya. pp. 225-230, 2016.
P. D. Kumbhar & P. B. Murnal, “Assesment of suitability of existing mix design methods of normal concrete for designing high performance concrete”, International Journal of Civil and Structural Engineering , Vol. 3 (1), pp. 158-167, 2012.
H. N. Ngugi, R.N. Mutuku, & Z.A. Gariy, “Effects of Sand Quality on Compressive Strength of Concrete: A Case of Nairobi County and Its Environs, Kenya”, Open Journal of Civil Engineering, Vol. 4, pp. 255-273, 2014.
R. Maciulaitis, M. Vaiciene, & R. Zurauskiene, “The effects of concrete composition and aggregates properties on performance of concrete”, Journal of civil engineering and management, Vol. 15 (3), pp. 317-324, 2009.
S. Ahmad, “Optimum concrete mixture design using locally available ingredients”, The Arabian Journal of Science and Engineering , vol. 31 (1B), pp. 27-33, 2007.
M. J. Mohamed, “Effect of Curing Method and Insoluble Residue in Cement On The Compressive Strength of Portland Cement Mortar”, Al-Qadisiya Journal for Engineering Sciences, Vol. 6, No. 1, pp. 74-80, 2013.
R. K. Dhir, M. C. Limbachiya, M. J. Mc Carthy & A. Chaipanic, “Evaluation of Portland Limestone Cements for Use in Concrete Construction”, Materials and Structures, Vol 40, pp 459-473, 2007.
K. Marar and Ö. Eren, “Effect of cement content and water/cement ratio on fresh concrete properties without admixtures”, International Journal of the Physical Sciences, Vol. 6(24), pp. 5752-5765, 16 October, 2011.
I. B. Muhit, S. Haque, and M. R Alam, “Influence of Crushed Coarse Aggregates on Properties of Concrete”, American Journal of Civil Engineering and Architecture, Vol 1 (5), pp. 103-106, 2013.
C. GONG, J. ZHANG, S.WANG & L. LU, “Effect of Aggregate Gradation with Fuller Distribution on Properties of Sulpho aluminate Cement Concrete”, Journal of Wuhan University of Technology-Mater. Sci. Ed. Vol 30, pp. 1029- 1035, 2015.
J. M Chi, R Huang , C. C Yang and J. J Chang, “Effect of Aggregate Properties on the Strength and Stiffness of Lightweight Concrete”, Cement and Concrete Composites, Vol 25 (2) pp. 197–205, 2003.
H. Donza, O. Cabrera & E. F. Irassar, “High Strength Concrete With Different Fine Aggregates”, Cement and Concrete Research, Vol 32(11), pp. 1755-1761, 2002.
W. Ke-Ru, B. Chen, W. Yao & D. Zhang, “Effect Of Coarse Aggregates Type on Mechanical Properties of High Performance Concrete”, Cement and Concrete Research. Vol 31(10), pp. 1421-1425, 2001.
M. S. Meddah, S. Zitouni & S. Belaabes, “Effect of Content and Particle Size Distribution of Coarse Aggregate on the Compressive Strength of Concrete”, Construction and Building Materials. Vol 24 (4) pp. 505-512, 2010.
A. Katz and H. Baum, “Effect of High Levels of Fines Content on Concrete Properties”, ACI Materials Journal. Technical Paper. Vol 103 (6) pp 476-482, 2006.
W. O. Oyawa, N. K. Githimba, & G. N. Mang'urio. “Structural response of composite concrete Filled plastic tubes in compression”, Steel and Composite Structures, Vol. 21, No. 3, pp. 589-604, 2016.
J. Dils, D. Schutter , & V. Boel, “Influence of Mixing Procedure and Mixture type on Fresh and Hardened Properties of Concrete A Review”, Materials and Structures Journal. 2012.
N. B. Singh, K. N. Bhattacharjee, & S. Rai, “Hydraulic Behaviour of Ternry and Quaternary Blended Cements”, Transactions of the Indian Ceramic Society, 57(3), pp. 81-84, 2014.
F. M. Wegian, “Effects of seawater for mixing and curing on structural concrete”, The IES J ournal Part A: Civil & Structural Engineering, vol. 3 (4), pp. 235-243, 2010.
C. N. Aginam, S. N. Umenwaliri, & C. Nwakire, “Influence of mix design methods on the compressive strength of concrete”. ARPN Journal of Engineering and Applied Sciences, vol. 8(6), pp. 438-444, 2013.
Kenya Bureau of Standards. KS EAS 18-1:2001- Cement Part 1: Composition, Specification and Conformity Criteria for Common Cements. Nairobi, Kenya Bureau of Standards, 2005.
D. O. Koteng', “Concrete use for Sustainable Development”, Presented at the 20th Engineers International Conference., The Institution of Engineers of Kenya., Kisumu, 2013.
D. C. Montgomery, Design and Analysis of Experiments (8th Ed.), John Willey and Sons. 2013.
S. Coruh, & S. Elevli, “Optimization Study of Dye Removal by Cement Kiln Dust Using The Central Composite Design of Experiments”, Global NEST Journal, vol. 17 (1), pp. 93-102, 2015.
M. Barbuta, E. Marin, S. M. Cimpeanu, G. Paraschir, D. Lepadatu, & R. D. Bucur, “Statistical Analysis of the Tensile Strength of Coal Flyash Concrete with Fibres using Central Composite Design”, Journal of Advances in Material Science and Engineering , pp. 1-7, 2015.
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