Plastic shrinkage and deflection characteristics of coconut shell concrete slab

Plastic shrinkage cracking and deflection characteristics of coconut shell concrete are studied and compared with conventional concrete. Five concrete mixes S1–S5 were considered with different percentage of coconut shell and crushed stone aggregate as coarse aggregate. Forty-five cube (nine cubes for each mixes) and five slabs (one slab for each mix) were tested. Study includes 7, 14 and 28 days density, compressive strength, total plastic shrinkage crack area, and the deflection characteristics. As expected, when the percentage of coconut shell decreases, the density and compressive strength of concrete are increased and vice versa. Plastic shrinkage crack area decreases and the deflection increases when the percentages of coconut shell aggregate increases. It shows that coconut shell concrete led to reduce plastic shrinkage cracking and more deflection compared to conventional concrete. Also coconut shell concrete gives warning before its failure compared to conventional concrete and satisfies the IS 456: 2000 code requirement of span to effective depth ratio. Hence, this investigation gives encouraging results for coconut shell to be used as coarse aggregate in concrete.