Laboratory and Field Investigations on Flowable Fill with Waste Soils and Fine-Grained Soils

Abstract Flowable fill has been widely used as a type of fill materials in engineering practice. However, the adoption of fine-grained soils, especially clay soils, in flowable fills faces difficulties such lack of mixing efficiency and poor engineering performance. In this study, the flowable fill was prepared using waste excavated soil generated from a construction project. Two types of soils, silty clay and silt mixed with silty sand, were used. In the laboratory tests, slump tests, unconfined compressive tests, oedometer compression tests, and drying shrinkage tests were conducted. Within the tested condition (8-10% cement addition and 10-50% water addition), the range of slump was 70-203 mm, and the range the 28d strength was 0.39 -0.67 MPa. For this project and most construction applications, these level of slump and strength are satisfactory. The construction process using the flowable fill has four steps, that is, raw soil filling, cement slurry preparation, flowable fill mixing, and conveying and filling. The details and the problems in the construction are introduced and discussed. Field experiments also confirmed that parameters such as slump, strength, deformation, can meet the design requirements.