Suat Akbulut

Estimating the groutability of granular soils: a new approach

This paper evaluates different parameters that affect the grouting of soil, and presents a new approach to predict the groutability of granular soil. An accurate prediction of the groutability of granular soils has always been complicated due to the effects of different soil parameters. We know that these parameters are the grain-size of soil and cement-based grouts, the relative density and fine contents of soil, the water/cement ratio of grout mixture and grouting pressure, which directly affect the groutability of soil media. However, the relative density, fine contents of soil, the water/cement ratio, and grouting pressure are seldom considered as the prediction of groutability. In order to study the effects of the parameters on groutability, an alternative empirical formula to estimate the groutability of granular soils is presented in this paper and supported by experimental results obtained from the grouted sand samples prepared with various relative densities. The newly developed approach will help for the more accurate prediction of the groutability in granular soils and may also be used to provide first-hand information about the groutability of soils.

THE DYNAMIC SHEAR MODULUS AND DAMPING RATIO OF CLAY NANOCOMPOSITES

Clay soils are very useful as liners in geotechnical structures such as landfill sites, dams, water channels, etc. Swelling is a common problem in clay liners, however. To better understand swelling properties, in the present study clay nanocomposites were produced by means of the sol gel method, using a hydrophobic clay, polymers (locust bean gum, latex, glycerine, vinyl acrylic copolymer), and rubber powder. The study focused on the swelling and dynamic properties (secant shear modulus and damping ratio) of the clay nanocomposites researched experimentally in laboratory conditions. The dynamic tests were conducted on samples compacted using two different compaction energy levels. The test results were compared with those of natural clay and hydrophobic organo-clay. The test results revealed that the damping ratios and secant shear modulus of clay nanocomposites without rubber (CNC) and with rubber (CNCr) that were compacted with both the E1 and E2 energy levels were increased and decreased, respectively. In addition, with increasing percentage of vinyl acrylic in nanoclay composites, the secant shear modulus values were decreased and damping ratio values were increased. Consequently, the test results found that the swelling and dynamic properties of clay nanocomposites can be optimized in order to attenuate the negative effects of dynamic loads on clay liners.