Pilot Use of Alternative Compliance Criterion for Cement-soil in a Slope Upgrading Works Project

Currently the General Specifications for Civil Engineering Works stipulates the use of in-situ density tests as compliance criterion for both compacted fill and cement-soil. However, the latter derives its strength from cementation between particles and could exhibit very high strength as opposed to the former whose strength closely relates to its density. Hence, the use of strength as a compliance criterion for cement-soil seems more direct and appropriate. This paper describes the pilot application of unconfined compressive strength as the compliance criterion for cement-soil in a slope upgrading works project. It details the field trial conducted prior to the production run to work out the mixing and placement procedures, the cement content to be adopted and identification of appropriate field control measure to augment the compliance criterion. It also covers the experience gained, the potential benefits of such application and areas where further optimisation could be achieved.