Elastic Modulus of Concrete Produced from Selected Coarse Aggregates

Frequent building collapses in Nigeria, often due to low-quality concrete with poor elasticity, have led to severe loss of lives and properties. In addition, the disposal of palm kernel shells (PKS), which is in abundant supply in some parts of the country, creates pollution and groundwater contamination. Many rural people living in the southern part of Nigeria use palm kernel shell in concrete production since it is a cheaper and very available alternative source of coarse aggregate. However, they have little or no understanding of its structural implications. This study is aimed at providing insight into the elastic modulus of concrete produced using contemporary granite aggregates and the PKS. This will aid in providing additional knowledge for the development of sustainable and green infrastructure. In this work, concrete was manufactured from Portland cement, river sand, coarse aggregates, and water. Coarse aggregates experimented were flaky granites (GC1), elongated granite (GC2), and the palm kernel shell (PKS) correspondingly. The water-cement ration (w/c) adopted were 0.45 and 0.5 for mix proportions 1: 1.5: 3, 1: 2: 3, and 1: 2: 4 respectively. Overall, the elastic modulus (EM) of the concrete produced using GC1 generated highest values for all categories of mix proportions tested. While those produced using PKS gave minimum results. The highest EM of concrete obtained was 29.12GPa at mix 1: 2: 4. 0.5 w/c. While the lowest was at 12.88GPa for 1: 1.5: 3 mix with 0.45w/c for PKS aggregates. Increase in w/c ratio slightly improved the EM of concrete produced from PKS except at mix 1: 2: 4. However, this led to a drop of EM for concrete produced using GC1 except at mix 1: 2: 4. ANOVA 2-way test showed that the choice of coarse aggregate played a major role in determining the EM of concrete, rather than the specific mix proportions. In conclusion, PKS can be used in making concrete for non-structural purposes, but the mix and water-cement ratios must be properly designed to achieve reasonable strength.