Statistical variations in impact resistance of polypropylene fibre-reinforced concrete

The impact resistance of polypropylene fibre-reinforced concrete (FRC) was investigated using the repeated drop-weight impact test recommended by ACI Committee 544. The results were analysed based on a statistical approach. The variation in results was examined within the same batch and between different batches. Statistical parameters were compared with reported variations in impact resistance of concrete composites reinforced with other types of fibres such as carbon and steel fibres. Statistical analysis indicated that the results obtained from this test had large variations and it is necessary to increase the number of replications to at least 40 specimens per concrete mix to assure an error below 10%. It is concluded that this test with its current procedures and recommendations should not be considered as a reliable impact test. This study has highlighted the need for modifying this test in such a way as to increase its accuracy and reduce the large variation in results.