SUMMARY
Peat soil was categorized as soft soil, which means that the soil is in bad condition and problematic when construction was built on it. It was necessary to increase the carrying capacity of peat soils, one of which is chemical stabilization of the soil, by adding additives that can react with the soil and using new environmentally friendly methods.In this study, samples of peat soil were taken from Buana Makmur Village km55, Dayun District, Siak Regency. The stabilizing agent used was sand as much as 5% by weight of dry soil, Bacillus Subtilis bacteria obtained from the Agriculture Laboratory of the Islamic University of Riau, and also CaCL2 and Urea. The method for stabilizing the physical properties of peat soil in this study is the Bio-Grouting method, testing the physical properties of peat soil follows the procedures of ASTM (American Society For Testing And Materials) and SNI 1965-2008 for testing methods for determining water content for soil and rock in the laboratory. SNI 1964-2008 test method for soil specific gravity, SNI 8460-2017 geotechnical design requirements, SK SNI -04-05-1989-F fine sand used for construction, SNI-02-2801-1998 urea standard. To test the physical properties was carried out by providing variations in the mixing of bacterial cementation solutions with levels of 0% (without treatment), 5%, 10%, 15%, 20%, and 25% and then allowed to stand for 14 days using a tightly closed plastic container.The results of testing the physical properties of peat soil found that the peat soil was included in the original soil type with water content = 407.45% and specific gravity (Gs) = 1.30gr, while from the physical properties tests carried out the highest water content occurred in the addition of bacterial cementation solution 10% = 177.2% and the lowest specific gravity occurs when the bacterial cementation solution is added 10% = 1.27gr.