Effective Mixing Lag Time of Two Phase Lime-Cement Stabilization on High Plasticity Clay

The use of soil–cement as pavement base material is one solution to the limitations of split rock in an area. The challenge of soil–cement use in Indonesia is how to increase the soil–cement strength to achieve requirements as a pavement material, especially in high-plasticity clay soils. One method of increasing soil–cement strength is to mix the soil with lime before it is mixed with cement and compacted. The mixing lag time must be sufficient so that the soil–lime chemical reaction runs well at once, but short enough to speed up the process of application. This paper presents the results of a laboratory study of the effect of mixing lag time on the UCS values of soil- cement-lime material. A series of physical properties, compaction and unconfined compression test according to SNI were performed on the untreated soil, and soil–lime-cement sample that prepared in mixing lag time 0, 2, 4 and 24 h. Lime content used is 2%, 6% and 10%, while the cement content is 10% of the soil dry weight. Grain size analysis and atterberg limit test performed to describe flocculation process and soil lime chemical reaction. The results of the study showed that the UCS value of sample prepared at 2 h and 4 h time-lag are 1/3 – 2/5 times UCS value of sample prepared at 24 h. The effective mixing lag time to provide sufficient soil–lime chemical reaction process is 24 h.