No abstract

Resilient modulus ( M R) which properly characterizes the load-deformation response of pavement materials under traffic loading, is evaluated. The M R values due to three different gradations and three different moisture contents were investigated for the Richard Spur and the Sawyer aggregates, which are commonly used in Oklahoma as the subbase or base materials of roadway pavements. The three gradations were finer limit, median, and coarser limit, as specified by the Oklahoma Department of Transportation for Type A aggregate. The three moisture contents selected are optimum moisture content (OMC), 2 percent below OMC, and 2 percent above OMC. To investigate the variability of the test results, six duplicate M R tests under identical conditions were performed for each case by using the AASHTO T294-94 method. Furthermore, the material properties, K1 and K2, which are required input in the AASHTO pavement design equation, were evaluated for the M R values obtained. Finally, multiple linear regression models for predicting the M R values of the two aggregates were established.

SUMMARYDurability is a notion that is integrated with the performance of stabilized pavement materials. Also, because it can be quantified and measured, it carries significant influence on the design of pavements. This study focuses on using support vector machine, a machine learning algorithm, in assessing the performance of stabilized aggregate bases subject to wet-dry cycles. Support Vector Regression (SVR) is a statistical learning algorithm that is applied to regression problems and is gaining popularity in pavement and geotechnical engineering. In our study, SVR was shown to be superior to the least-squares (LS) method. Results of this study show that SVR significantly reduces the mean-squared error (MSE) and improves the coefficient of determination (R 2 ) compared to the widely used LS method.

The effect of wetting/drying and freezing/thawing on the resilient modulus values of Meridian limestone aggregate stabilized with cement-kiln-dust is investigated. Freezing/thawing is found more detrimental than wetting/drying at low deviator stresses. In addition, the stabilized aggregate suffers greater strength reduction during the initial stages of the freeze/thaw test. On the other hand, wetting/drying produces greater strength reduction at high deviator stresses. The layer coefficients of the stabilized aggregate base, which are significantly higher than those of the raw aggregates, are reduced appreciably due to freezing/thawing and wetting/drying.