An investigation of the shrinkage, concrete shrinkage reversibility and permeability of CO2-treated concrete

The uptake of CO2 gas into recycled aggregate to create CO2 Concrete both improves the properties of recycled aggregate and traps the greenhouse gas. This paper aims to investigate and compare the performance of CO2 Concrete against that of the ordinary virgin aggregate concrete in terms of shrinkage, concrete shrinkage reversibility and permeability. To complete the objective CO2 Concrete is compared to virgin aggregate concrete in examinations such as drying shrinkage, its shrinkage reversibility and water permeability. Whilst utilising optimal carbonation variables with a 120-minute duration and a 25 kPa pressure CO2 Concrete is able to consistently achieve similar to greater performance than the virgin aggregate concrete for both the drying shrinkage and permeability. The CO2 Concrete always surpassed the performance of the untreated recycled aggregate concrete. CO2 Concrete with 30 % and 50 % recycled aggregate content surpassed the virgin aggregate concrete in many cases whilst the 100 % replacement could provide a similar performance with optimised carbonation variables. The employment of various cements can also be utilised within CO2 Concrete whilst still appreciating an enhancement. The concrete shrinkage reversibility of the concrete largely did not correspond to aggregate quality and therefore the injection of CO2 is negligible for the parameter.

Automated summary

This paper investigates and compares the performance of CO2 Concrete and ordinary virgin aggregate concrete in terms of shrinkage, concrete shrinkage reversibility, and permeability. The results show that CO2 Concrete consistently achieves similar to better performance than virgin aggregate concrete for drying shrinkage and permeability. CO2 Concrete with 30% and 50% recycled aggregate content outperforms virgin aggregate concrete in many cases. The injection of CO2 does not significantly affect the concrete shrinkage reversibility.