Use of recycled aggregates for cementitious backfill Available to Purchase

Laboratory and field trials were conducted to assess the performance of cementitious backfill material for reinstatement of trenches and excavations in roads. Backfill material was produced using recycled granular aggregates, pulverised fuel ash and cement. A conventional compacted recycled granular material was used as a control to compare the performance of cementitious backfill. The results showed that recycled granular materials, with a particle size ranging from 5 to 38 mm, could be used to form a cementitious backfill with strengths that comply with the Highway Authorities and Utilities Committee's Specifications for the Reinstatement of Openings in Highways (SROH) for cementitious backfill. This backfill was prepared using conventional mixing plant and was straightforward to install on site. Settlements of trenches with granular backfill up to 1 year of monitoring were found to be higher than the corresponding ones with cementitious backfill. However, settlements for both types of backfill were within the limits of the SROH and did not require any subsequent intervention measures. Although the stiffness of the granular backfill was initially lower than that of the surrounding ground, within a year it had increased to the same level. The cementitious backfill was stiffer than the adjacent ground, but no detrimental effects were observed over the period of monitoring.