Improvement of silty soil with lime and rice husk ash

Nowadays, the soil improvement is a very important issue. For this purpose, shallow and deep improvement methods are widely used. In this thesis, the improvement of a silty soil sample with lime and rice husk ash was investigated. As a result of the improvements, changes in the engineering properties of the soil have been examined numerically. Firstly, geotechnical properties of soil samples were determined. Soil specimens whose geotechnical properties were determined were improved by using lime, rice husk ash and lime + rice husk ash. The pH method was used to determine the optimum lime content of the soil sample. As a result of pH test, optimum lime amount was determined as 5%. 5%, 10%, 15% and 20% rice husk ash was added to the ground for soil improvement. Finally, lime and rice husk ash was added to the soil. For this purpose, two different amounts of lime and 4 different amounts of rice husk ash were added to the soil. Compaction experiments were performed on the soil samples that were improved. In the test results, optimum lime amounts and maximum dry unit volume weight values were determined for natural soils and for improved soils. As a result of the experiments, it was seen that optimum water content values increased and maximum dry unit volume weight values decreased when lime and rice husk ash was added to the ground. In order to determine the strength values of soil samples with compaction properties, Unconfined Compression test and California Bearing Ratio (CBR) tests were performed. With the addition of 5% lime to the natural soil sample, the instant undrained shear strength value was 30 kPa, but it reached 86 kPa at the end of the 28-day curing period. An increase of approximately 3 times has occurred. If 20% brass husk ash was added to the natural soil sample, the instant undrained shear strength value was 30 kPa, but it increased to 48 kPa after 28 days curing time. Although there was some increase with the addition of rice husk ash alone, there was no significant increase. When 5% lime + 20% rice husk ash was added to the natural soil sample, the instant undrained shear strength value increased from 30 kPa to 186 kPa as a result of the curing period of 28 days. As a result of experimental studies, it was seen that undrained shear strength values of the soil increased with curing time. As a result of CBR experiments, swelling and CBR values were examined. Swelling value of natural soil sample was 1.45 cm, 5% lime was added to the ground and after curing for 28 days, the swelling value decreased to 0.03 cm. Similarly, with the addition of rice husk ash to the ground, the swelling values decreased. The CBR value of the natural soil sample at the end of the 28-day curing period was 6% while the addition of 5% lime and this value increased to 33% after the 28-day curing period. As a result of the CBR experiments, the natural sample was 6%, while the addition of rice husk was 20%. The greatest increase in CBR value was achieved by adding lime and rice husk ash together. As a result of the permeability tests, it has been observed that permeability is reduced with the addition of lime to the ground. If rice husk ash is added, the permeability of the ground is increased. If two additives were added together, the permeability was reduced. As a result of the experiments carried out within the scope of the study, it was observed that the physical properties of the soil improved with the addition of lime and rice husk ash together or separately. In the light of this information, it has been seen that it is appropriate to use rice husk ash which is produced as waste as a result of rice production.