Properties of high-performance cementitious composites containing recycled rubber crumb

It was observed that the drying shrinkage is neglectable after hot water curing at either 90 °C or 60 °C for HPCC-R. Under normal curing condition, drying shrinkage development follows the similar trend as the base material but end up with approximately 20% higher shrinkage at 28 days' age. The compressive strength and flexural strength of both HPCC-R and HPFRCC-R decrease significantly with the increase of the amount of rubber crumb. Applying hot water curing at 90 °C and pre-treatment of rubber crumb using Na(OH) were identified as effective approaches to compensate the compressive strength loss. However, it was observed that impacts of different curing conditions are insignificant on the flexural strength development. The rapid chloride permeability test (RCPT) results of HPFRCC-R material under different curing conditions were at the same level, and as good as that of the base material. Mixing scheme of using rubber crumb as filler material instead of replacement of fine sand lead to better material performance regarding its compressive strength versus density ratio at a relatively high replacement ratio of 40% by volume. It is recommended to use “Addition” mixing scheme when a large amount of rubber crumb being used in HPFRCC in the future.