Hydraulic and Leaching Characteristics of Recycled Materials Used in Pavement Construction.

Generation of waste in household, industry, and highway reconstruction has spurred recycling nationwide. One of the venues for use of recycled materials is in pavement construction. However, there is limited information on hydraulic, strength, stiffness, and leaching properties of these materials when mixed with granular aggregates often used for base construction. In this study, we characterized water retention, hydraulic conductivity, and leaching characteristics of 4 recycled materials mixed in with class 5 granular aggregates. The recycled materials were reclaimed asphalt, reclaimed concrete, fly ash, and foundry sand. The recycled materials were mixed with granular aggregates at various ratios to produce seventeen mixtures. Hydraulic and leaching measurements were made after the mixtures have been brought to optimum water contents and then packed to maximum densities using a gyratory compactor. Water retention characteristics were characterized from near saturation to –1000 kPa matric potential. Hydraulic conductivity and breakthrough curves were characterized at saturation and -5 kPa matric potential. Samples from the breakthrough experiment were characterized for heavy metal leaching. In this presentation, we discuss the differences in hydraulic and leaching characteristics between various recyclable materials as well as between various mixtures of the same material with granular aggregates.