Analysis of strength development in soft clay stabilized with cement-based stabilizer

• The mechanical properties of soft clay stabilized with cement-based stabilizer were investigated.
• The predicted models for compressive strength and secant modulus were analyzed.
• The effect of the supplementary cementing materials was confirmed by SEM imaging.

Sodium silicate and promoters have been widely used as supplementary cementing materials substituting ordinary Portland cement to improve the properties of stabilized soils. In this paper, the developments of mechanical properties of specimens stabilized with cement-based stabilizer, which consists of cement, sodium silicate and composite promoter, is investigated by unconfined compressive strength (UCS) test and scanning electron microscope (SEM). The failure strain and secant modulus are also obtained in UCS tests. The test results indicate that the supplementary cementing materials perform effectively pozzolanic reactions and improve the mechanical properties of cement stabilized clay. The contribution of pozzolanic effect is regarded akin as an addition of cement and the total cement content is the summation of cement content and equivalent cement content of the supplementary cementing materials. According to this premise, the clay–water/cement ratio hypothesis for stabilized clay is proposed for analyzing and assessing the development of the mechanical properties. The phenomenological models for predicting the compressive strength and secant modulus of specimens stabilized with the selected cement-based stabilizer are developed and verified. The comparison of predicted results and laboratory results indicates that the deviation is mostly within 10%. The microstructural analysis observes the changes of cementitious products in stabilized clays and confirms the pozzolanic effect of the supplementary cementing materials. On account of the efficiently pozzolanic effect, the addition of sodium silicate (<2%) and composite promoter (<4%) can be equivalent to several times cement content. Hence, the economic and environmental mix design is developed with the addition of the supplementary cementing materials.