Perbaikan Kuat Tekan Bebas Tanah Gambut Dari Kabupaten Siak Menggunakan Metode Microbially Induce Calcite Precipitation

ABSTRACT In the world of civil engineering construction built on peat soils, there are many problems that must be faced, such as the strength of the peat soil. This can be dangerous and detrimental to the construction of the building above it. Therefore, it is necessary to improve the soil to achieve the desired bearing strength. The biogrouting technique is one method that is being used in stabilization of peat soils. This study aims to determine the effect of biogrouting techniques on the free compressive strength of peat soil with the help of the bacterium Bacillus subtilis. The original peat soil was taken at the location of Buana Makmur Village km 55, Dayun District, Siak Regency, the bacteria material came from the Agricultural Laboratory of the Islamic University of Riau as well as additional materials used for stabilization, namely CaCl2 and Urea from Bandung producers. This research method refers to ASTM (American Society for Testing and Materials) and SNI procedures. The test object was made using a sondir modification tool with a cylinder shape with a diameter of 3.64 cm and a height of 10.75 cm2. The object was made following standard compaction at an optimum moisture content of 157%. The free compressive strength test is carried out after the test object is added with bacterial reagents with variations of 0%, 5%, 10%, 15%, 20%, and 25%. The data obtained from the results of this test were processed in the form of tables and graphs according to the variation of the addition of bacterial reagents. The results of the physical properties of the original peat soil show that the soil originating from the location of Buana Makmur Village km 55, Dayun District, Siak Regency is a type of peat soil with a moisture content of 407.5% and a specific weight (Gs) = 1.3. From the test results of the free compressive strength of the original soil specimens with variations in the mixture of bacterial reagents at a percentage of 0%, 5%, 10%, 15%, 20%, and 25%, the value of the free compressive strength of the original soil test object + the addition of 0% bacterial reagent amounted to 0.30 kg / cm2, whereas with the addition of a variation of 5% bacterial reagent of 0.33 kg / cm2, the addition of 10% bacterial reagent was 0.36 kg / cm2, the addition of 15% bacterial reagent was 0.40 kg / cm2, addition of 20% bacterial reagent of 0.43 kg / cm2, and addition of 25% of bacterial reagent of 0.45 kg / cm2