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.