Dynamic properties of soil-rubber mixtures

Abstract

Recently, many studies were conducted on the use of waste rubber in civil engineering projects. Rubber’s high damping capacity make it a suitable engineering material in soil-rubber mixtures to reduce vibration in seismic design.

In this project, the dynamic properties of various soil-rubber mixtures were investigated. A series of test was carried out in a modified triaxial cell with bender elements. Compression (P) and shear (S) wave signals were obtained at different frequencies (S wave – 3, 5 and 10 kHz and P wave – 10, 20 and 50 kHz) and confining pressure (0, 100, 200 and 400 kPa). Specimens used were of different fines content (5, 20 and 40%) and rubber content (0, 15, 30, 60 and 100%). Results from these tests were used to determine the initial shear modulus (Gmax) and damping ratio (ξmin). The damping ratios (ξmin) were determined through the use of Spectral Ratio, Log Decrement and Hilbert Transform method. Ultrasonic transducer tests were also conducted and compared with the bender element test.

Results obtained from the bender element test showed that damping ratio increases with increasing rubber content and decreasing confining pressure. The Gmax on the other hand decreases with increasing rubber content and decreasing confining pressure. The effects of the different parameters of the soil-rubber mixtures on the properties of the specimen were discussed.