PROPERTIES AND PERFORMANCES OF SOIL CEMENT MODIFIED WITH CONCENTRATED PARA-RUBBER

Due to the slump of the price of Para-rubber, the Department of Highways of Thailand has adopted the rubber to be used in the quality improvement of cement stabilized materials. Hence, this research aims to study the changes of properties of soil cement modified with concentrated Para-rubber. Lateritic soils were mixed with cement, at the ratio of 1, 3 and 5%, and Para-rubber, at the ratio of 1 and 2% of dry soil weight. The shear wave velocity (Vs), unconfined compressive strength (UCS), strain at failure, indirect tensile strength (IDT), resilient modulus (MR), fatigue resistance (FR) and soil permeability (k) were tested after 7 days of curing. The results indicated that UCS increased with the increase of cement ratio but tended to decrease with the increase of Pararubber which were consistent with the results of Vs. For the performance tests, IDT and MR tended to decrease while FR and k tended to increase with the increase of Para-rubber. It was expected that Para-rubber affected the compaction quality and, probably, the creation of a hydration reaction. Conclusively, the addition of cement increased the brittleness of the material resulting in higher strength. On the other hand, the addition of Para-rubber increased the ductility resulting in lower strength but higher deformation and higher fatigue crack resistance.