Hakan Sahin

Estimation of Resilient Modulus of Unbound Aggregates Using Performance-Related Base Course Properties

AbstractThis study aims at developing an accurate and efficient methodology to estimate the resilient modulus of unbound aggregates. First, a new resilient modulus model is proposed to incorporate the moisture dependence of the resilient modulus in addition to the stress dependence in existing models. Second, prediction models are developed to conveniently and accurately determine the coefficients in the proposed model. In order to characterize the moisture dependence of unbound aggregates, the degree of saturation and the matric suction parameter are added into the proposed model. The soil-water characteristic curve (SWCC) is used to determine the matric suction value at any given moisture content. The moisture dependence of the model is validated for selected materials with different moisture contents. In order to develop prediction models for the coefficients in the proposed model, laboratory experiments and multiple regression analysis are conducted on 20 different base course materials. The laborator...

Development of Soil-Water Characteristic Curve for Flexible Base Materials Using the Methylene Blue Test

AbstractThis study describes an experimental investigation of the methylene blue test to determine the methylene blue value (MBV) and quantitatively generate the soil-water characteristic curve (SWCC) for unbound aggregate material based on the predicted percent fines content (PFC). The traditional methylene blue test has been improved significantly in terms of time, sample size, and method for analyzing the results. These improvements enable the methylene blue test to be not only a laboratory test but also a field test. This improved methylene blue test methodology is used to generate the SWCC for unbound aggregate material. The relationship between the MBV and the PFC value is established. The principles of unsaturated soil mechanics are taken into account to develop regression models for determining the four fitting parameters in a previously developed SWCC equation by using the predicted PFC value, which are then used to generate the SWCC for the unbound aggregates. The proposed method is validated by...