Experimental Investigation of the Physical and Mechanical Properties of Cassava Starch Modified Concrete
Daniel Oluwabusayo ONI1, *, John Mwero2, Charles Kabubo3
1 Department of Civil Engineering, Pan African University Institute of Basic Science, Technology and Innovation Hosted at Jomo Kenyatta University of Agriculture and Technology, Nairobi 62000-00200, Kenya
2 Department of Civil Engineering, University of Nairobi, Nairobi 30197-00100, Kenya
3 Department of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology, Juja, Kenya
Concrete is a widely used material in construction, which has given rise to innovations in terms of modifying some of its properties to meet desired requirements. The use of chemical admixtures is important in this regard, which has necessitated the search for new materials which can serve as a substitute.
This research work investigates the use of Cassava Starch (CS) as an admixture for improving the physical and mechanical properties of concrete.
The physical and mechanical properties of concrete were studied by adding CS by weight of cement at 0.4, 0.8, 1.2, 1.6 and 2.0%, respectively. Concrete cubes and cylinders were cast and cured for a test period of 7, 14, 28, 56 and 90 days, respectively. Unreinforced beams of size 150 x 150 x 530 were cast and cured for 28 days. A total of 6 mix proportion was used, five out of which were used to examine the effect of CS on the properties of concrete.
The workability of concrete reduced as the percentage of CS increased due to its viscosity modifying properties. CS increased the initial and final setting time of concrete for every increase in percentage addition. An improvement in the compressive strength, split tensile strength, flexural strength and elastic modulus of concrete were noticed for cassava starch-modified concrete over the control for some of the mixes at all days of curing. The density of concrete was found to decrease at 1.6 and 2.0% addition of CS in concrete.
From the results of this investigation, CS improved the compressive, split tensile, flexural and elastic modulus of concrete at an optimum of 0.8 percentage addition of CS. The setting time of concrete was also increased, which makes CS suitable to be used as a retarding admixture in hot weather concreting. Based on the findings of the work, CS can be considered as an admixture to be used as a substitute for retarders and viscosity modifying admixtures for improved concrete properties.
Keywords: Cassava starch, Setting time, Workability, Compressive strength, Split tensile strength, Flexural strength, Density, Static modulus of elasticity.
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* Address correspondence to this author at the Department of Civil Engineering, Pan African University Institute of Basic Sciences, Technology and Innovation, JKUAT – Juja Campus, PAU Building Block B, Nairobi 62000-00200, Kenya Tel: +254 743607787; E-mail: firstname.lastname@example.org