CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractThe increased scarcity of natural quarry material has resulted in increases in the cost and burden on the environment. Pavement materials comprising asphalt coated aggregates that can be reused are called reclaimed asphalt pavement (RAP). RAP is crushed and screened, and then blended with one or more stabilization agents to produce a stabilized base or subbase aggregate. In the present study, the influences of fly ash dosage, lime dosage, and curing period on the strength, stiffness, and durability characteristics of RAP fly ash–lime (RFL) mixes were studied for utilization as a base layer material in flexible pavements. The dry density and moisture content relationship were determined by conducting a modified proctor test on all RFL mixes. Unconfined compression tests were conducted on specimens with different dry weight percentages of fly ash (10%–25%) and lime (5%–10%) content for different curing periods (0, 7, and 28 days). The optimum mix obtained as RFL2 had the proportions 70% RAP:22.5% fly ash:7.5% lime. A resilient modulus of 540 MPa at 28 days was observed for RFL2. The durability of RFL2 tested using the resistance index and a wet–dry cycle (weight loss) was observed to be 0.88% and 7.3%, respectively. Pavement analyses were performed for a pavement system with three layers using the KENLAYER program. The RFL2 mix as the base layer material was found to be superior to conventional wet mix macadam, hence the service life of an RFL2 pavement would be higher. Trial sections of the stabilized base and conventional pavement were constructed on a major district road. The falling weight deflectometer showed a better modulus (286 MPa) in RFL2. An RFL mix could therefore be used in a stabilized base layer to replace a conventional base layer.



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