A holistic review on the structural performance of concrete incorporating palm kernell and coconut shells: an approach to waste management and production of sustainable green composite

The wrong disposal of agricultural residues constitutes environmental pollution and climate challenges to the world. Amongst the consequences of environmental pollution is frequent emission of greenhouse gases (GHGs) from waste, most especially carbon dioxide (CO2) which usually affects the Ozone layer. One of the ways in managing these wastes is by incorporating them into cement composites thus contributing to the nation’s building and infrastructures sustainability. This approach reduces environmental pollution by 50% which has positive influence on global economics and also complements the performance of concrete. The use of Coconut and Palm Kernel Shells (CS & PKS) in concrete has been aging, their holistic reinforcing influence on concrete structural properties should be given a critical evaluation. This study reviews the structural properties of concrete incorporating CS and PKS. The focus is to highlight the potential of CS and PKS and their ashes for the production of cement composites. The review shows that CS and PKS ashes (CSA & PKSA) consist of about 77.5 and 85% of pozzolans respectively making good supplementary construction material in cement and concrete industries. Also, as reviewed, the 0–5% of CSA and 8–25% of PKS / PKSA were found suitable for the production of sustainable green concrete with good strength and low CO2 emission which perform better than that of conventional concrete in service. In addition, the density, compressive, flexural and tensile strengths of CSA – concrete are by 1.12, 27.65, 52.24 and 28.54% more than that of normal concrete at 30, 5, 1, and 5% of CSA while that of PKS – concrete are by 1.89, 3.92, 5.89, and 60.34% better at 10, 25, 8 and 9% of PKS accordingly. Also, concrete produced with 20% of CSA and PKSA are less porous, have good microstructure and hydration mechanism with high water resistance capacity. Thus, CSA and PKS are recommended for the production of sustainable light—normal weight concrete and future studies should focus on the ternary or quaternary utilization of these wastes. Also, since incorporation of CS and PKSA in concrete increased the concrete’s mechanical, microstructural, hydration and durability properties; blending them with other highly pozzolanic materials will advance their good performance in concrete. Future research and construction practice should also work on this.