Temperature Correction for FWD Deflection in Cement Pavement Void Detection

Bei Zhang,Xiaolong Li,Xiaoliang Wang,Yanhui Zhong,Meimei Hao,Jianyang Liu,Yuanhao Ding,Xu Zhang,Jiaolong Ren

doi:10.1155/2021/6668003

Abstract

The use of the falling weight deflectometer (FWD) for detecting pavement voids is based on the principle that, under the same impact load, the deflection of pavements with voids increases significantly. Under the effect of temperature, the cement pavement becomes warped, which affects the deflection detection accuracy. In order to improve the accuracy of FWD detection of cement pavement voids, a three-dimensional numerical model of cement pavement on a multilayered elastic foundation under the coupled action of temperature and load is established in this paper. In addition, under different pavement void, climatic, and load conditions, the influence of temperature difference between top and bottom of the plate on the deflection of the center point of plate angle load is studied. Considering the temperature difference between top and bottom, the temperature correction coefficient is established and experimentally verified the accuracy of the temperature correction coefficient. The results showed that, within the ranges of positive and negative temperature differences, the fitting degree of the temperature correction coefficient for the cement pavement exceeded 0.99, which was consistent with the variation trend of the temperature correction coefficient obtained through field tests. The error was lower than 7%, which verified the applicability of the temperature correction coefficient for the dynamic deflection of cement pavements based on FWD. The accuracy of the FWD method in detecting cement pavement voids was improved, and this study demonstrated theoretical reference value and practical engineering significance.

Highlights

Cement concrete pavement structures have advantages of extended service life, strong load diffusion capacity, easy constructability, accessibility of constituent materials, and low cost, and they are widely used for all types of highways [1]
During the service life of cement pavement, the pavement is prone to experience cracks, disconnections, voids, and other problems, owing to the combined action of the driving load and external environment. ese problems have a significant impact on driving comfort and human safety [2]; the most significant impact on traffic is attributed to the voids in the cement concrete pavement [3, 4]
Scholars have investigated the detection of voids in cement pavements, among which the most widely used technique is the void determination method based on the deflection. e void determination method is mainly divided into two types: falling weight deflectometer detection and Benkelman beam test [5, 6]. e FWD detection is used more widely because of its established technique and easy implementation

Summary

Introduction

Cement concrete pavement structures have advantages of extended service life, strong load diffusion capacity, easy constructability, accessibility of constituent materials, and low cost, and they are widely used for all types of highways [1]. Scholars have investigated the detection of voids in cement pavements, among which the most widely used technique is the void determination method based on the deflection. Sheng et al proposed improvement measures for the deflection test on old cement concrete pavements, evaluated the deflection of the solid engineering plate angle, plate center, and joint edge, and determined the reasonable temperature of the deflection test [23]. E research results are useful for improving the accuracy of the FWD method for detecting cement pavement voids in different climates. A three-dimensional numerical model of cement concrete pavement was established for the analysis of the influence of the temperature field on the deformation of a cement concrete pavement slab. Material Parameters. e model size and material parameter setting of each structure layer were determined (Table 2) to simulate the actual cement concrete pavement structure better

Load and Boundary Conditions

Temperature Correction for Dynamic Deflection of Cement Pavement

Field Test Verification

Findings

Conclusion