Published Online: 10 August 2005
Page Count: 8
Graduate Research Assistant, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL
Assistant Professor, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, IL
(Received 4 December 2003; accepted 18 March 2005)
Differential expansion and contraction between the top and bottom of a concrete slab results in curling. Curling affects slab stresses and deflections and is an important component of any mechanistic-empirical design procedure for concrete pavements. Although some curling is caused by temperature and moisture gradients that fluctuate daily, a significant portion of the curling can be attributed to the combined effects of nonlinear “built-in” temperature gradients, irreversible shrinkage, and creep, which can be represented by an effective built-in temperature difference (EBITD). A procedure for estimating EBITD of in situ slabs using a falling-weight deflectometer and a finite-element program is presented. This procedure was used to estimate EBITD for instrumented slabs at Palmdale and Ukiah, California. Differences in restraints (from adjacent slabs, shoulder, base friction) and variability in concrete material properties resulted in EBITDs ranging from -5°C to greater than -30°C.
Paper ID: JTE12338