Effect of aggregate type on Compressive strength of concrete

The utilisation of three types of aggregate for concrete work is investigated in this paper. Normal concrete is being produced from different types of aggregate and this imparts different property to the resulting concrete. The most important property of concrete is its compressive strength. For the purpose of this work, three types of coarse aggregates, quartzite, granite, and river gravel, were used. The fine aggregate is normal sand obtained from a borrow pit. Preliminary laboratory investigation was conducted to ascertain the suitability of using the aggregates for construction work. Tests conducted include sieve analysis, bulk density, and specific gravity. Nominal mix (1:2:4) was adopted for this work and mix compositions were calculated by absolute volume method. For each type of coarse aggregate 75 cubes (150x150mm) were cast to allow the compressive strength to be monitored at 3, 7, 14, 21, and 28 days. Test result show that concrete made from river gravel has the highest workability followed by crushed quartzite and crushed granite aggregates. Highest compressive strength at all ages was noted with concrete made from quartzite aggregate followed by river gravel and then granite aggregate. Compressive strength models were proposed as a function of age at curing. Where concrete practitioners have options, aggregate made from quartzite is advisable to be used for concrete work.