Investigation Properties of Pervious and Water-Retaining Recycled Concrete to Mitigate Urban Heat Island Phenomena

The urban heat island (UHI) effect poses significant challenges to urban environmental
quality and public health. Over the decades, research efforts have been made to develop various UHI
mitigation strategies, including pavement materials, such as, water-retentive pavement, reflective
pavement, and pervious concrete. This paper focuses on the improvement of the hygric and water
retention properties of pervious concrete to mitigate UHI phenomena. The hydric and hygroscopic
tests were carried out under dry and wet conditions on four different pervious concretes, where
natural aggregates were replaced with recycled aggregates at different mass percentages. The results
show a significant improvement in these properties by increasing the amount of recycled aggregates
incorporated in the mixtures. The mixes made from recycled aggregates alone showed an absorption
that reached 75 L more than the control in one cubic meter under wet condition. With an upwelling
capacity of up to 30 kg of retained water in a square meter under dry condition, these improvements
in water performance represent this permeable concrete as a water retention pavement solution for
UHI mitigation. Regarding the mechanical properties, a decrease of 50% in compressive strength
was noted only when 100% of the recycled aggregate was incorporated, remaining at 20 MPa for
other mixtures.