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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.

A study was conducted to determine the effect of reinforcement on the fatigue lives of asphalt beams of size 76 × 76 × 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 from three different sets of the beams were analyzed to determine the effect of reinforcement on the fatigue lives of the beams. These analyses indicated that the beams reinforced with composite performed significantly better than the beams containing paving fabric alone, and the beams reinforced with fabric alone performed better than the unreinforced control beams. Further details of the study and the results are described.

THE PAPER DISCUSSES APPLICATION OF FRACTURE MECHANICS TO THE ANALYSIS OF FATIGUE CHARACTERISTICS OF PAVING MIXTURES. A METHOD OF DETERMINATION OF CRACK GROWTH PARAMETERS FOR ASPHALTIC BEAMS RESTING ON ELASTIC FOUNDATION IS PRESENTED. THE FINITE ELEMENT METHOD OF ANALYSIS IS USED FOR THE DETERMINATION OF STRESS INTENSITY FACTORS FOR VARIOUS CRACK SIZES. THE EFFECT OF MATERIAL CHARACTERISTICS, FOUNDATION MODULUS, AND MODE OF LOADING ON THE CRACK GROWTH PROCESS OF ASPHALTIC MIXTURES, IS DISCUSSED. THE EFFECT OF ASPHALT PENETRATION ON THE PARIS CRACK GROWTH LAW IS SHOWN. IT IS ALSO SHOWN THAT FRACTURE MECHANICS PRINCIPLES CAN BE USED TO PREDICT FATIGUE LIFE OF PAVEMENT MATERIAL. /ASTM/

This report describes the investigation of the suitability of various dynamic testing devices to be used with carbon-carbon composites at strain rates greater than 104/sec. These investigations have resulted in the selection and preliminary design of split Hopkinson bars to be used for compression, tension, and shear testing of composite materials, particularly carbon-carbon composites. Specimen sizes have also been investigated, and bar dimensions have been selected based on minimum specimen requirements. The availability and suitability of various strain measuring and data storage/digitizing equipment have been explored, and an instrumentation package has been recommended. Composite material, Dynamic properties, High strain rate, Strain rate effects, Hopkinson bar, Carbon-carbon material.