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Self-Compacting Materials for Trench Backfilling

To minimize inconvenience to the public due to road excavation works, we strive to explore innovative self-compacting materials to improve efficiency and quality of trench backfilling such that duration of temporary closure of public road for underground utility installations and maintenance can be shortened.

Road excavations for utility installations and maintenance with substantial volume of trench excavation are commonly carried out in order to improve the living quality in Hong Kong. Since road pavements are normally constructed with soil support, the soil underneath the road will first be excavated before the installation or maintenance of underground utilities and then backfilled with compacted soil for reinstatement. However, it is sometimes difficult to carry out proper soil compaction in road sections with congested underground utilities. To address the above problem, we have carried out study on the feasibility to use a self-compacting backfill material which is highly flowable and easy for filling up space. Using it to replace soil for trench backfilling can therefore help to reduce road repair works arising from improper compaction of soil. Currently, we collaborate with a local research institute, Nano and Advanced Materials Institute (NAMI), to support the research and development of such self-compacting backfill material. Site trials on the use of the new backfilling material on public roads are being carried out with a view to overcoming the challenges above.