Chhote L Saraf

Effect of Reinforcement on Fatigue Life of Asphalt Beams

A study was conducted to determine the effect of reinforcement on the fatigue lives of asphalt beams of size 76 X 76 X 610 mm, which were prepared in the laboratory with a typical surface layer asphalt mix. Three sets of nine beams each contained no reinforcement (control beams) and reinforcements consisting of nonwoven paving fabric and composite (woven grid and nonwoven fabric composite). Each set of beams was subjected to three different load levels (three beams were tested at each load level), and their fatigue lives were determined. The fatigue testing of these beams was carried out by placing the beam on an elastic foundation (approximately 150 mm deep, 76 mm wide, and 660 mm long) and loading the beam at the center. A fatigue load at a frequency of 2 cycles/sec was applied to each beam. Each load cycle consisted of a half sine wave of 0.1-sec duration and a rest period of 0.4 sec. The total number of fatigue loads to crack the entire depth of beam was recorded as its fatigue life. The data obtained...

Dynamic Response and Fatigue Characteristics of Asphaltic Mixtures

This investigation deals with the influence of several mix variables in respect to asphaltic concrete on its fatigue response. The investigation was based on a simple model representation comprising a beam supported on elastic foundation subjected to sinusoidal repeated loading, thus providing a two-dimensional simulation of actual pavement conditions under traffic loads. The dimensions of the beam were designed such that plan strain conditions prevailed during fatigue loading. Fracture mechanics concepts using linear elastic theory were employed to analyze test data, including stress and deformation near the crack tip. It was also hypothesized that the parameter, A, in the rate-of-crack-growth equation, dc/dN = A K 4 would adequately reflect the changes induced in the fatigue response of the mix by the selected mix variables. The effect of mixture variables such as the amount of binder, density, aging, and viscosity on the parameter A is investigated.

Application of Innovative Tools in Optimizing Risk and Cost of Subgrade QA/QC

During the reconstruction of the Ohio Turnpike, data were collected from construction sites using non-destructive tools. This study was done in two phases: the first one included using the Light Weight Deflectometer (LWD) and Automatic Dynamic Cone Penetrometer (ADCP) to evaluate the subgrade, which was recommended to be stabilized. The second phase included using the Falling Weight Deflectometer (FWD) and Ground Penetration Radar (GPR) to evaluate the structural capacity of the entire pavement. The data generated from these tests were statistically analyzed and compared with traditional measurements to develop QA/QC procedures that optimize risk and cost. This article sheds lights on the first phase of the study, which was mainly concerned with subgrade characterization using LWD and ADCP. The ADCP and LWD data correlated fairly well. Both the ADCP and LWD provide a measure of stiffness, whereby the nuclear density gauge provides a measure of density. In comparison, the LWD seems to be the most promising QA/QC candidate. It was the most cost-effective among the three tests, had the highest rate of production, and was the most reliable.