A testing procedure for predicting strength in artificially cemented soft soils

Abstract

It is globally recognized that soft soils will have low strength and high compressibility and that under reduced loads might collapse or suffer large displacements. In order to reduce settlements and increase bearing capacity of structures built on such soils, their stabilization using cementitious materials such as Portland cement and/or quicklime (increasing strength and stiffness) is an efficient technique used worldwide. The focus of this research is to present and check the accuracy of a new testing procedure to evaluate strength gain in very soft soils when using cementation as a means of improvement. This testing procedure was intended to fasten acquiring strength results in artificially cemented soft soils. In short, in the proposed procedure the force applied to embed a flat base rod into a soil mass is measured by using high resolution load rings. The proposed flat base rod embedding test was shown to be adequate for evaluating the gain in strength of cemented soils. Results of embedding flat base rod strength have unique linear relations with both unconfined compressive strength and splitting tensile strength, being independent of type and amount of cementitious material (Portland cement and/or quicklime), as well as of the curing time period. The wrap up of present studies is that the developed testing procedure can be used as a substitute of unconfined compression and splitting tensile tests as a dosage test, being easier to mold specimens (might be molded in the field) and faster in acquiring strength results (can be carried out in a bucket filled with soil and the cementitious material, in which will be attached to the load ring) in artificially cemented soft soils.