Ultimate Shear Strength of Sand to Concrete Interface

One several studies have been performed by many researchers regarding laboratory interface testing. Interface tests were performed to determine the soil to structure shearing resistance angle (δ). This angle is used for the design of geotechnical structures such as friction piles, retaining walls, culverts, etc. Also, test results are useful for determination of parameters for constitutive modeling of interface response. Correlations between sand relative density, and corresponding friction angle (Ø), and interface shearing resistance angles (δ) are obtained. In addition, (δ) is represented as a function in (Ø). These relations are based on degree of interface roughness and particle shape of sand. Two types of sand, and in addition one mix (50%-50%) of the two sand types, are investigated. The first type of sand is siliceous sand and has rounded to sub-rounded particles. The second type of sand is fragments of weathered igneous rock of granite and basalt. This type of sand has angular shaped particles. To form a surface representing the retaining structure, ordinary Portland concrete mix was made from locally available material (sand, ordinary Portland cement and potable water). The mix was then poured into a steel mold having 4 sides 59 mm long, and 19 mm high to fit into the shear box bottom half. In order to simulate a smooth surface of concrete, the mold was placed on to smooth plastic sheet, and then the paste is poured into the mold. Interface tests have been performed on many types of soil-to-structure, soilto-rock, and rock-to-rock interfaces. In this section, previous studies of soil-to-concrete and soil-to-steel interfaces are emphasized. The results of tests performed on both types of interfaces provide valuable insights into fundamental aspects of interface behavior.