Performance evaluation of modified marine dredged soil and recycled in-situ soil as controlled low strength materials for underground pipe

Abstract

The purpose of this research was to present engineering properties of Controlled Low Strength Materials (CLSM) with recycled insitu soil and marine dredged soil as backfill materials for underground pipe line system. The proper mixing ratio was determined, based on the specified criterion of flowing size and unconfined compression strength. Laboratory tests were carried out in this research included particle analysis, unconfined compression test, direct shear test, dynamic creep test and small scaled laboratory chamber test. The unconfined strength and flow of controlled low strength materials satisfied the criteria for construction materials, which was above 250 kPa. The measured creep strain at 1200 sec longing was 178 μm for Case 3 (natural sand with dredged soil CLSM) and 178 μm for Case 4 (recycled in-situ soil with dredged soil CLSM), and 471.9 μm for natural soil only. The use of CSLM can reduce the settlement of backfill materials for underground pipe line system. The use of CLSM as backfill materials made a large reduction of earth pressure applied on underground pipe. The use of small amount of cement gives the cementation effect for both CLSM and hardening effect.