Modification of Soil Permeability Using Shredded Rubber
Mentor:Binod Tiwari, Associate Professor Civil Engineering Department, California State University Fullerton
There is a growing need to limit human impact on the environment, such as the disposal of rubber tires in landfills. By reusing those rubber tires in construction projects, we can save money and reduce our carbon footprint. Clayey materials are not recommended in civil engineering applications due to their poor drainage properties, which reduces the strength of soil significantly. Improvement of drainage potential of those clays by adding shredded tires can save construction costs. Moreover, adding shredded rubber tires in clays also has the added benefit of possibly decreasing the amount soil swells during large rainstorms, which would decrease the amount of damage done to roads due to soil swelling. There are no studies available in literature that deal with these issues. Kaolin clay is considered as one among those low draining materials. In this study, shredded rubber tires of 10-30 mesh size were mixed with kaolin clay at various proportions ranging from 2 to 30% by weight. The mixture was compacted in a 5cm diameter and 15cm tall cylinder and Falling Head Permeability tests were conducted for each mixture, using the ASTM standard. The test results showed that the addition of less than 2% shredded rubber doesn’t increase the permeability of soil. However, the permeability consistently increases if the proportion of tire is more than 2%. The permeability of kaolin clay without rubber tire was measured to be 4.06E-07 cm/s using a falling head permeability test. With the addition of 10%, 20%, and 30% shredded tires in kaolin clay, permeability of the mixture increased by 3, 4, and 10 times, respectively. This shows that disposed rubber tires can be advantageously used in improving the drainage potential of poor clays. The long-term goal of this study is to develop a permeability model for composite materials such as kaolin-tire mixture.