Behaviour of Coconut Shell Aggregate (CSA) Concrete at Elevated Temperature

This paper attempts to study the mechanical behaviour of coconut shell aggregate (CSA) concrete subjected to elevated temperatures when coconut shell (CS) is used to replace coarse aggregate at 0, 10, 20 and 40% in concrete. The coconut shell used was obtained by breaking the shells into smaller sizes of less than 20mm after the fibres were removed. In order to produce control concrete samples with a minimum compressive strength of 15N/mm2 at 28 days curing age, mix ratio of 1:2:4 and water-cement ratio of 0.55 were adopted alongside Absolute Volume Method (AVM) to prepare the concrete mix proportions for this research. The specific gravity of the concrete materials were determined as well as the workability of the fresh coconut shell aggregate concrete at various replacement using slump tests. Compressive strength of 48 samples prepared at various CSA replacements using 100mm x 100mm x 100mm cube mould and cured for 28 days was determined after 30 minutes exposure to temperatures of 100, 300 and 500oC. Splitting tensile strength of 18 samples prepared at various CSA replacements using 200mm x 300mm cylinder mould and cured for 28 days was also determined after 30 minutes exposure to 500oC temperature. The results of this study showed that at 10% replacement and 500oC temperature, CSA concrete exhibits good behaviour in compressive strength and splitting tensile strength as it retained 67.3% and 53.7% of its strength respectively; as well as having a higher strength reduction coefficient (Kc(θ)) of 0.673 in compressive strength compared to the 0.60 allowed for siliceous aggregates in BS EN 1992-1-2 [26]. However, slump results showed that CSA concrete has a very low workability. So, CSA can be used up to 10% to replace coarse aggregate in concrete to serve in non-load primary application areas.