Integration of Pavement Layer Evaluation Using LWD for Road Safety Control

Abstract

As one of Thailand transport policies currently aims to reduce the death rate of road and traffic accident, the Department of Highways authorities shall involve and raise awareness of the road construction quality control and its long-term performance. Light Weight Deflectometer (LWD) is gaining acceptance and popularity over years as the pavement and transportation geotechnics community is currently moving toward more mechanistic-based design and quality control evaluation of pavement layers and fill embankment. In this study, the LWD was used to measure the surface deflection, d, and elastic modulus, ELWD, of pavement layers over 11 highway construction sites in Thailand as well as to evaluate for the feasible adoption by Thailand Department of Highways as a construction quality control device on the routine basis. A range of d and ELWD values for four major types of pavement materials commonly used in Thailand highway construction including crushed rock base, soil-aggregate subbase, selected material, and subgrade was reported. The coefficient of variation of the d and ELWD of these pavement materials ranged from 58 to 77% and 49 to 65%, respectively. Such large variability can be explained due to the test site, material, testing configuration, moisture content, density, and compacted thickness. The correction factor applied for different test configurations was also proposed for practical implications. Finally, the number of empirical relationships between the measured values from the LWD and basic properties of various pavement materials indicated that they were generally in agreement with the conceptual relationships. The LWD device was found to be a quick test for direct measurement of pavement surface deflection and layer moduli and it was also simple to operate on any pavement layers. Therefore, increasing frequency of quality control tests can be anticipated, resulting in an improvement in the overall quality of compacted pavement layers and its long-term performance.