Mahmoud Malakouti Olounabadi

Roller-compacted concrete, a type of concrete with zero slump, is being used in road pavement construction. The use of recycled asphalt in roller-compacted concrete is an enviromental approach for reducing emissions. This study examines the impact of recycled asphalt aggregate and nano-silica on the strength behavior of roller-compacted concrete. Cylindrical samples were fabricated to determine optimal moisture content and maxi-mum dry density. The compressive strength, along with stress and strain curves at optimal moisture, were evaluated. Additionally, the surface area under the stress-strain curve and energy absorption were measured. Results indicate that adding asphalt aggregates decreases the optimal moisture con-tent in roller-compacted concrete. Conversely, nano-silica increases the op-timal moisture content and enhances the maximum dry density of the sam-ples. Replacing recycled asphalt with coarse aggregate revealed a decrease in compressive strength of roller-compacted concrete samples at both 7 and 90 days. Moreover, nano-silica did not improve the reduced compressive strength, with its negative impact being more pronounced at 90 days than at 7 days. The study also found that recycled asphalt increases the area under the stress-strain curve and enhances energy absorption. However, adding nano-silica to control samples and those with recycled asphalt does not im-prove ductility or energy absorption.