Value-added utilisation of recycled concrete in hot-mix asphalt.
The feasibility of partial substitution of granite aggregate in hot-mix asphalt (HMA) with waste concrete aggregate was investigated. Three hybrid HMA mixes incorporating substitutions of granite fillers/fines with 6%, 45% untreated, and 45% heat-treated concrete were evaluated by the Marshall mix design method; the optimum binder contents were found to be 5.3%, 6.5% and 7.0% of grade Pen 60/70 bitumen, respectively. All three hybrid mixes satisfied the Marshall criteria of the Singapore Land Transport Authority (LTA) W3B wearing course specification. The hybrid mix with 6% concrete fillers gave comparable resilient modulus and creep resistance as the conventional W3B mix, while hybrid mixes with higher concrete substitutions achieved better performance. X-ray diffraction (XRD) showed the distinct presence of free lime in the heat-treated concrete, while the scanning electron microscope (SEM) provided an in-depth perspective of the concrete grains in the HMA matrix. The results suggest feasible use of waste concrete as partial aggregate substitution in HMA.
School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Yiik Diew
YD
Wong
Darren Delai
DD
Sun
Dickson
D
Lai
D017610:Calcium Compounds; D003247:Conservation of Natural Resources; D003252:Construction Materials; D006838:Hydrocarbons; D010087:Oxides; D014961:X-Ray Diffraction
D017610:Calcium Compounds; D006838:Hydrocarbons; D010087:Oxides; C006647:asphalt; C016538:lime