Effect of SAPs and polypropylene fibres on the freeze-thaw resistance of low carbon roller compacted concrete pavement

Most concrete currently used in pavement is based on Portland cement (PC), being responsible for 8-10% of total CO2 emission. Moreover, external pavements are subjected to exposure classes XF4 and XD3 which are related to corrosion and freeze-thaw. Freeze-thaw resistance is an important durability property of concrete, especially for concrete pavements that are subjected to the de-icing salts. This study was designed to explore the freeze-thaw resistance and mass scaling resistance of low carbon Roller Compacted Concrete (RCC) in the presence of water and de-icing salts. Four different RCC mixes were used with a water/binder ratio of 0.45. PC was replaced with 80% ground granulated blast-furnace slag (GGBS) in all mixes to develop low carbon concrete and move towards a more sustainable cementitious composite. To assess the effectiveness of smart engineered additives, superabsorbent polymers (SAPs) were used at 0.3% by weight of total binder, and Polypropylene (PP) fibre with 12-mm length at fibre volume fractions of 0.3% for the mitigation of freeze-thaw damage. The compressive strength, freeze-thaw resistance, and mass scaling resistance of concrete specimens were evaluated. The results indicate that both additives improved the compressive strength and freeze-thaw resistance of concrete with and without de-icing salts. The inclusion of PP fibre was more effective compared to the addition of SAPs to mitigate the extent of internal structural damage and mass scaling of self-healing concrete mixes with respect to the reference concrete after 56 freeze-thaw cycles.