Estimation of Layer Coefficients for Flexible Pavement Design and Development of a Practical and Rational Mix-design

Download or read book Estimation of Layer Coefficients for Flexible Pavement Design and Development of a Practical and Rational Mix-design written by and published by . This book was released on 1994 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pavement layer coefficients had been identified as essential parameters to use the 1986/1993 AASHTO Guide for Design of Pavement Structures (AASHTO guide) in Rhode Island. Layer coefficients of granular subbase materials were estimated using the direct method recommended by AASHTO Guide. Resilient moduli were determined using a pneumatic testing system. Coefficients based on resilient moduli ranged from 0.08 to 0.14, and the average was 0.12 for eight subbase samples in Rhode Island. The pneumatic testing system was also used to determine resilient moduli of bound layeres. Based on results of a series of testing, layer coefficients were estimated using moduli at the loading magnitude of 20% of tensile strength and loading frequency of 0.5Hz. Recommended coefficients for wearing course (Class I-1), modified binder, and modified asphalt base were 0.40, 0.42, and 0.43, respectively. If all asphalt bound layers will be analyzed as one layer, the coefficient of 0.41 was recommended for pavement design and analysis in Rhode Island. Field study including FWD testing was performed to verify laboratory test results. Laboratory determined moduli were compared with backcalculated moduli based on FWD deflection data. Generally, FWD moduli are consistently higher than laboratory moduli with a wide range of variability. For the covering abstract of this conference, see IRRD number 863140.