Flexural behavior of RC beams incorporating recycled concrete aggregate and reclaimed asphalt pavement exposed to elevated temperatures

Reducing the environmental footprint of concrete is one of the most effective methods to mitigate climate change since cement production contributes to about 8% of global CO2 emissions. This paper presents an experimental investigation into the strength and flexural performance of reinforced concrete (RC) beams incorporating natural aggregate (NA), recycled concrete aggregate (RCA), and reclaimed asphalt pavement concrete (RAP) at normal and elevated temperatures. The NA was replaced by RAP at three replacement ratios of 40%, 60% and 80%. Additionally, there were four mixes of 80% RCA-20% RAP, 60% RCA-40% RAP, 40% RCA-60% RAP, and 20% RCA-80% RAP. A total of 16 beams (L: 1400 mm, W: 150 mm, H: 250 mm) and 128 cylinders (H: 200 m, D: 100 mm) were tested to evaluate the flexural capacity and material strength. Eight RC beams were tested after exposure to a temperature of 600°C for 3 hours. The compressive strength, ultimate flexural load, and mid-span deflection were measured. The results showed that temperature has an adverse effect on the s compressive strength, flexural load capacity, and deflection of RC beams. Specimens made with the RAP and RCA combination showed a significant loss in their load-carrying capacity under elevated temperature by (55% to 65%), while the temperature effect was relatively less severe in specimens made with high RAP replacement of NA. Increasing the RAP percentage increased the reduction of flexural capacity in RCA-RAP mixes by (3% to10%), while in NA-RAP mixes, the effect is similar except for 60% RAP, which has a smaller reduction compared to 40% and 80% RAP.