Browsing by Author "Kumaran, Senthil G."

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    Analyses of Deteriorating Old Masonry Buildings; Characterisation of Materials for Establishment of their Compatible Repairs
    (2015) Makunza, John K.; Kumaran, Senthil G.
    Most of the Governmental and religious building structures in Rungwe district are masonry structures built during the German East Africa period. These structures are deteriorating despite of various efforts on their repair intervention using modern cements and paints. This paper studies the types of mineral binders used, composition and physical characteristics of these in-situ mortar materials for the purpose of deciding on their appropriate compatible repair materials. Field observations and investigations, laboratory materials testing and review of the literature showed that the in-situ mortar materials constituted of sub-hydraulic lime mineral binders to natural sand (1:3) mortars. Currently there are no producers of hydraulic lime in Africa and a limited production worldwide. Mix design and analysis of locally available hydrated lime plus pozzolana natural sand (1:3) mortar material have shown compatibility in chemical and major physical properties and characteristics with the substrate in-situ hardened sub-hydraulic masonry mortars. Therefore use of these repair mortars is recommended for compatible repairs to these masonry structures and as a regional alternative to cement based materials for low rise masonry structures.
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    An Investigation on the Behaviour of Concrete with Waste Tyre Rubber Fibres as a Partial Replacement of Coarse Aggregate
    (Trans Tech Publications, 2012) Kumaran, Senthil G.; Lakshmipathy, M.; Mushule, Nurdin K.
    Concrete is an excellent structural material and considered as essential for the modern civilization and human society. Now, use of waste tyres in concrete has become technically feasible and the concrete is being considered as light weight concrete. The composites were formed with 0%, 5%, 10%, 15%, 20% and 25% of fibers replaced by coarse aggregate weight. The fibers were of different lengths (L) such as 25mm, 50mm and 75mm had holes of diameters (D) 4mm, 5mm and 6mm. The holes functioned as anchors in the cement matrix so that the tyre fibres shall not be separated while placing in the mould. The 3rd, 7th and 28th day’s compression strength and crack patterns were observed on cubes. Split tensile strength on 14th and 28th day were tested on cylindrical specimens. Test results have shown that the increase in rubber content decreases the compressive strength, but, increases the strain energy while conducting the split tensile tests. The composite with fiber specimen L50-D5 and L50-D6 with 10% replacement of coarse aggregate had shown better results than other specimens. However, further studies are needed to reveal the hidden properties of tyre fiber modified concrete.