The recycled road: A field study showcasing the use of recycled aggregate concrete pavements

Virgin aggregate is being used faster than it is being made available creating a foreseeable shortage in the future. Despite this trend, the availability of demolished concrete for use as recycled concrete aggregate (RCA) is increasing. Using this waste concrete as a replacement aggregate source, reduces the impact on landfills, decreases energy consumption and can provide cost savings. Four test sections containing 0%, 15%, 30% and 50% coarse RCA were constructed in June 2007. The test sections had identical cross sections consisting of 250 mm Portland cement concrete, 100 mm asphalt-stabilized open graded drainage layer (OGDL) and a 450 mm granular base. For each coarse RCA content, one slab was instrumented with six vibrating wire concrete embedment strain gages to measure long-term longitudinal and transverse strain due to environmental changes, two vibrating wire vertical extensometers to monitor slab curling and warping, two vibrating wire inter-panel extensometers to monitor joint movement, and two maturity meters to measure maturity and temperature. Quality assurance and quality control testing showed that the mixes containing RCA exhibited similar or improved performance when compared to the conventional concrete for compressive and flexural strength, freeze-thaw durability and coefficient of thermal expansion. Pavement performance was evaluated using visual surveys following the Ontario Ministry of Transportation's Manual for Condition Rating of Rigid Pavements. All test sections are in excellent condition with pavement condition index values greater than 85 after two years in-service. Sensor data from the strain gauges, and vertical and inter-panel extensometers are providing consistent results between the test sections.