Long-Term Performance of Recycled Concrete Aggregate for Subsurface Drainage

Abstract

Recycled concrete aggregate (RCA) is one of many sustainable construction materials, and its use in drainage systems by replacing virgin aggregate is beneficial from both economic and environmental perspectives. However, the use of RCA as pipe backfill material may cause a long-term performance issue such as clogging due to fine accumulation and calcite precipitation on filter fabric. Therefore, this study investigated long-term performance of RCA regarding flow rate and calcite precipitation. Long-term permeability testing was conducted to measure the reduction of flow rate with time, and the effect of filter fabric’s opening size on the flow was also evaluated. Additionally, an accelerated calcite precipitation (ACP) procedure was devised and used to estimate lifetime calcite precipitation of RCA. Two key findings are: (1) excessive RCA fine accumulation can cause significant reduction in RCA’s drainage performance; and (2) the clogging due to calcite precipitation of RCA may not be as significant as the existing and/or accumulated RCA fine.