Evaluation of Temperature-Induced Curling in Concrete Slabs Using Deflection Difference Analysis

Abstract

The curling and warping of rigid pavements are the results of temperature and moisture gradients varying with depth, creep, and other factors, including construction. The indicators commonly used to evaluate slab deformation include a combination of deflections derived from a heavy-weight deflectometer (HWD) that are measured at specific locations on pavement slabs. Indicators comprise the sum of deflections (SD) across the joints and the impulse stiffness modulus (ISM) deflection ratio. The objective of this study was to identify the best indicator that can be employed for assessing the slab curling level relationship to temperature. The study was included in a project developed by the U.S. Army Engineer Research and Development Center (ERDC) and sponsored by the Federal Aviation Administration (FAA). At selected military bases, HWD testing on concrete slabs was executed on two different occasions toward the end of summer and in winter. These tests were conducted to monitor slab deflections under different temperature conditions to quantify a correlation between measured deflections and temperature. The analysis showed that the SD rather than the ISM ratio could be adopted as an indicator to determine the relative degree of slab curling. The proposed approach to analyze deflection parameters showed promising results, and with a dedicated database and intensive testing, it is believed possible to refine the regression analysis and increase its level of determination. The proposed methodology for analyzing SD and temperature differences can be adopted in those cases intended to evaluate curling trend relationships to construction or curing techniques.