Influence of different curing conditions on the transport, durability and microstructural properties of concrete paver block mixes containing RAP aggregates

Recycling of extracted asphalt pavement materials, also known as reclaimed asphalt pavement (RAP), is gaining tremendous interest among researchers globally due to the depletion of good quality natural aggregate reserves and has been successfully employed for various pavement applications. However, an integrated curing condition-based performance assessment is necessary to understand the possible utilisation of these recycled aggregates for precast units like concrete paver blocks (CPBs), which fail to adhere to the standard curing procedures to support mass production. Therefore, the present study attempts to examine the suitability of RAP fractions (coarse, fine, and combined in volumetric proportions of 50% and 100%) for CPB mixes considering the effectiveness of five different curing conditions. The CPB specimens were fabricated implementing a pragmatic design methodology to cater to the need for agglomerated RAP particle refinement and promote maximum utilisation of RAP. The performance assessment mainly focussed on the transport, durability and microstructural properties of hardened CPB specimens subjected to prolonged water curing, air curing, water and air curing, water spray and air curing, and heat curing conditions. Similar to conventional precast concrete mixes, an initial 7 days of water curing or water spraying followed by air curing could be suggested as an alternative curing method to continuous water curing for RAP-based CPB mixes, thereby promoting RAP utilisations in the precast concrete industry from an economic viewpoint. Large voids or pore spaces and micro cracks for the heat cured counterparts make heat curing unsuitable for RAP-based CPB mixes.