Evaluation of the Use of Recycled Concrete Aggregate in French Drain Systems

摘要

Recycled concrete aggregate (RCA) is often used as a replacement for virgin aggregate in road foundations (base course), embankments, hot-mix asphalt, and Portland cement concrete. However, the use of RCA in exfiltration drainage systems, such as French drains, is still uncommon. The primary concerns with using RCA as drainage media are excessive fines and calcite precipitation that can cause a reduction in permeability performance. This study investigates the potential benefits of RCA as drainage material. This paper presents and discusses: (1) the results of a nationwide survey on current practices and policies, (2) physical and chemical properties, (3) effective fine-removing methods, (4) re-cementation potential, (4) permeability (under varied fine content), and (5) long-term drainage performance of RCA as drainage material. Test results indicate that RCA No. 4 gradation does not restrict the flow of water, but the RCA fines being generated during aggregate handling process (e.g., stockpiling, placing and transporting) may cause clogging buildup over time.