The aim of the study was to determine the effect of different sizes of coarse aggregates on the splitting tensile strength of
concrete. Preliminary investigations using ACI mix design method for test such as splitting tensile strength of the different
aggregates sizes were conducted. The aggregates (fine and coarse) used for the concrete were collected from gneiss rock
deposits from L-Adisa, along Ojoo-Moniya Road, Ibadan. The aggregates were sun-dried and sieved to different sizes
with the set of sieves: BS sieve 19mm, BS sieve 13.2mm, BS sieve 9.5mm, BS sieve 4.75mm, and were classified based on
aggregates passing the aforementioned sieves in the Department of Civil Engineering. Splitting strength test were
conducted after duly checking ages of curing to ascertain its relatedness to structural failures. The result was an increase
in splitting tensile strength of concrete at 7days (with 5.71Mpa for concrete of coarse aggregate size of 19mm), rising to
splitting tensile strength of 6.94Mpa after 28days. There was increase in splitting tensile strength of concrete made from
different sizes of coarse aggregates based on progressive increase in curing age. Similarly, there was corresponding
decrease in the splitting tensile strength of concrete as coarse aggregate sizes decreased. So, from these results it was
deduced that, generally, the bigger the mean size of aggregates (MSA), the greater the splitting tensile strength of
concrete, so long the coarse aggregates are properly graded and the maximum size of aggregates used doesn’t exceed
1/5th of the least dimension of the concrete work.
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