Study of the Effect of Plastic Aggregates on Drying Shrinkage and Expansion of Concrete

Abstract

The aim of this work was to propose a possibility of using plastic aggregates from waste to reduce the shrinkage and expansion observed in concrete. The process of obtaining plastic aggregates was presented. Natural aggregates were partially substituted by plastic aggregates in the percentages: 0%, 5%, 10%, 20% and 30%. Drying shrinkage, water absorption and expansion tests were carried out on three families of concrete: control concrete (BT), concrete with addition of BAgP-PEHD high-density polyethylene plastic aggregate and with polyvinyl chloride BAgP-PVC. Given the slow appearance of the internal sulfate attack (ISA), an experimental technique was proposed to accelerate the appearance of this pathology. This technique involves heat treatment which stimulates the heating of the concrete at a young age, followed by a cycle of drying and cooling and ends with total immersion in water. The method of measuring expansions through sample image correlation was also proposed. The results showed an increased skrinkage of BAgP-HDPE compared to BT. On the other hand, a significant decrease in shrinkage was observed in BAgP-PVC samples. Water absorption increased in BAgP-HDPE and BAgP-PVC compared to BT. Greater expansion was observed at the cement paste-plastic aggregate interface than at the cement paste-natural aggregate interface. Given these properties, BAgP-PVC can be recommended for paving surfaces exposed to the hard weather conditions.