| Summary: | The expansive soils in Indonesia is estimated to cover 10% of the total land area. Not a bit of building construction as it was built on the expansive soils and not a few others who suffered damage such as cracks, collapse and others, it happen because a cycle of shrinkage and swelling that places repetitive stress on structures. Until now the soil stabilization is always strived to repair this type of soil.This research try to used vulcano ash that combined with lime as a soils stabilizing to resolve the issue with a view to improve the technic properties of soil in particular to reduce the level of swelling in the soil. The research was conducted by mixing native soil with stabilizing material (volcano ash and lime). The research is divided into 2 preliminary testing of soil physical properties and the main testing is swelling of the soil with oedometer. Specifically for testing swelling soil with oedometer sample are γb = 1.6 and γb = 1.7. Native soil sample mixed with vulcano ash with a different variety 5%, 10%, 15%, 20%, 25% and 30% with the addition of lime fixed at 5%. The result showed that vulcano ash and lime can be improve the nature of shrinkage and swelling of the soil. This is evidenced by the liquid limit (LL) decreased by 25.3%, shrinkage limit (PL) decreased 12.8%, plasticity index (IP) decreased 13.74%, shrinkage limit (SL) decreased 5.8%. Soil with γb = 1.65, if we compared with a native soil, the swelling preasure is 6.01% and Soil with γb = 1.7, the swelling preasure is13.71 %. According to the test results AAS content, heavy metals that contained in the vulcano ash (30%), lime (5%) and soil (65%) were Cu = 0.0046, Fe = 4.6, Pb = 0.0038, Mn and Zn = 0.180 = 0.097 . According to the Government Regulation No.90 of class B, heavy metals contained in the sample is qualified as a construction site.
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