A Field Study on the Utilization of Recycled Concrete Aggregate in Drainage Systems

A field study of the exfiltration behavior of French drain system built with recycled concrete aggregate (RCA) as a pipe backfill material was conducted. This study was designed to evaluate the long-term exfiltration performance of four types of French drain systems in the field test. Each French drain system was constructed with different aggregate type and condition, which involve limestone, RCA ‘as is’, RCA with 2% and 4% additional fines. To evaluate the exfiltration performance of RCA French drain systems, field and laboratory tests were employed. From the field test, the flow rate and discharge rate of French drain systems were monitored and measured for 12 months to estimate an average permittivity of each trench in the field. Two laboratory tests of this study included exfiltration test of nonwoven geotextiles and material characterization of RCA fines were conducted. Geotextiles were excavated and taken from the four RCA French drain systems after 12 months and tested to measure the average permittivity. The results of field and laboratory tests show that major factors affecting the exfiltration performance of French drain system are permeability of surrounding soil condition and groundwater table in the field. The aggregate type (RCA or limestone), on the other hand, is a minor factor affecting the exfiltration performance of French drain system. In conclusion, the utilization of RCA as a pipe backfill material in a drainage system causes no significant reduction in exfiltration performance of a drainage system in comparison with the natural aggregate (limestone).