The research, clay characteristic was improved with Portland Cement and rice husk. The important parameter of clay was improved are Liquid Limit (LL), Plastic Limit (PL), and Plastic Index (PI). This research was done on the clay disturb from Grobogan, Purwodadi. To improve clay characteristic (soil stability) is used Portland Cement 4%, 6%, 8%, and rice husk 2% of the weight soil with curing time 3 and 7 days. Laboratory test include specific gravity, Proctor Standard compaction test, consistency limit test (Atterberg Limit), water content test and unconfined compression test. The test result showed that clay which is from Grobogan Purwodadi belonging to un-organic clay based on USCS with plasticity 30,04%. Addition of Portland Cement 4%, 6%, 8%, and rice husk 2% able to increase plastic limit (PL). to reduce Liquid Limit(LL) and Plasticity Index (PI) specially, the addition of Portland Cement 8% and rice husk 2% with curing time 3 days able to reduce plasticity index 8,29% and addition of Portland cement 6% and rice husk 2% with curing 3 days able to improve the gradation size
Keyword : Liquid Limit, Plasticity Index, Stability,