As with the previous two symposia, the 32 papers from the June/July, 1999, Seattle symposium present advances in the nondestructive testing of pavements using conventional falling weight deflectometer techniques and other promising techniques such as ground penetrating radar, rolling weight deflecto

The proceedings of June 1993 international symposium held in Atlanta, Georgia, called specifically to develop and standardized evaluation procedures for non-destructive methods of testing pavements. The 29 papers discuss analytical models and techniques, measurement and calculation techniques in the field and laboratory, problems and errors associated with backcalculation methods and design parameters, and testing for other pavement uses. Also includes a history of the quest for a standard and the status of that effort. Reproduced from typescripts. Annotation copyright by Book News, Inc., Portland, OR

FWD testing was completed on three urban arterial sections and six residential streets prior to and after rehabilitation to select the appropriate layout for FWD testing, establish joint performance threshold values, optimize FWD testing time and cost, and evaluate the effect of asphalt overlays on joint performance parameters. Moreover, the performance of full-depth repairs (FDR) and the incorporation of joint performance at the design stage were studied. Residential streets joint and basin FWD testing was completed to evaluate the structural capacity of residential streets and compare their performance to arterial regional roads. Comparisons between two widely used FWD geophones layouts allowed for the selection of a layout that represents the more critical loading condition on joints. Peak deflections and differential deflections were correlated with load transfer efficiencies to select threshold values for LTEs, peak deflections and differential deflections to trigger rehabilitation at the appropriate time. Statistical testing was used to optimize FWD testing to two load levels instead of four. The study found that asphalt overlays reduce recorded deflections and overestimate computed joints performance parameters. The effect of asphalt overlays was evaluated to establish correction factors, Fasphalt, for each load level to estimate deflections on the concrete surface using deflections obtained from testing on the overlay surface of Pembina Highway. The correction was found to improve the reliability of joint condition evaluation for that site. The study also found that FDRs generally restore the load transfer capacity of joints with good support and mechanical load transfer achieved. Moreover, it was demonstrated that joint performance information can be used at the design stage in the decision-making process to select the location and type of joint repairs. Lastly, residential streets were found to have less load transfer capacity than arterial regional roads and weaker pavement structure. The findings from this study indicated that NDT can be used to evaluate pavement condition, determine layer stiffness for use in rehabilitation design and to improve planning of rehabilitation through timely determination of rehabilitation needs and improvement of the reliability of load transfer efficiency estimate and void detection of PCC joints.

Proceedings of the 10th Regional Conference for Africa on Soil Mechanics and Foundation Engineering and the 3rd International Conference on Tropical and Residual Soils, held in Maseru, Lesotho, September 1991, are contained in two volumes. The papers address geotechnical problems peculiar to Africa and engineering solutions for local problems, as well as data on the properties of African soils.

This report documents the results of one FIS technology transfer initiative: the demonstration of nondestructive pavement evaluation technology (NDT) to cooperating Federal and non-federal partners. The demonstrations utilized Falling Weight Deflectometer (FWD) technology, a commercially available nondestructive procedure for determining the structural adequacy of a pavement system. Data obtained from FWD tests were combined with pavement material properties and estimated future traffic volumes to design rehabilitation strategies for the existing streets and roadways of three communities. The specific objectives of the study were to: (1) Evaluate and develop improvements to the initial guide specification used for contracting FWD technology; (2) Evaluate the three analytical methods used by each contractor to develop the pavement repair strategies; (3) Document and explain the differences in the results of the pavement evaluation methods; (4) Document the benefits of FWD technology over other conventional techniques; and (5) Transfer nondestructive testing of pavements technology to non-federal partners, and demonstrate how analysis of the test results can be used to develop rehabilitation strategies for roadway pavements. (MM).