this report, shape changes induced by vertical moisture gradients in the slab are referred to as warping. These changes typically do not vary much day to night, as do temperature gradients, but typically increase from construction. The size of the moisture gradient typically varies somewhat from wet season to dry season. Shrinkage and shrinkage gradients follow a seasonal pattern with an underlying monotonic increase as hydration continues. 15 Tensile stresses caused by uniform shrinkage, and shrinkage-gradient induced warping are additive with tensile stresses caused by uniform changes and temperature gradient induced curling. Less stiff bases offer similar benefits in reducing tensile stresses from shrinkage and temperature changes. Higher strength concrete reduces the risk of cracking, as does shorter slab length. Construction practices that reduce differences in moisture, and therefore shrinkage between the surface and the bottom of the slab are extremely important as well. These practices include sealing the surface of the concrete and protecting it from heat and wind. Saw cutting of transverse and longitudinal joints as soon as the concrete is strong enough to support the equipment and provide clean cuts also reduces the risk of temperature- and shrinkage-induced cracking by relieving tensile stresses caused by contraction. 1.3 Tradeoffs between Strength, Stiffness, and Stresses Tradeoffs exist between strength, stiffness, and tensile stresses. Early-age cracking occurs when tensile stresses exceed tensile strength in the concrete. However, the "easy" solution of increasing the strength of the concrete, or reducing the stiffness of the concrete, does not solve the problem. The task of optimizing a pavement for early-age cracking resistance is more complex and req...

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Dynatest TABLE OF CONTENTS Table of Contents................................................................................................................. i List of Figures..................................................................................................................... ii 1.0 Introduction............................................................................................................. 3

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In an attempt to better understand and predict concrete pavement behavior, the incorporation of material and climatic factors in mechanistic-empirical design methods is fast becoming a necessity. With the wide range of climatic regions in the United States, the inclusion of localized factors can have a profound effect on the observed critical distresses and fatigue life of rigid pavements. A mechanistic analysis and design software (RadiCAL) was developed employing an influence line approach in conjunction with Miner’s Hypothesis to calculate the fatigue damage at numerous locations in the slab for typical jointed plain concrete pavement sections. Permanent built-in curling of concrete slabs, stress range-based concrete fatigue transfer functions, and the inclusion of self-equilibrating stresses from non-linear temperature profiles were found to have considerable effects on the predicted location and magnitude of concrete fatigue damage. A parameter named NOLA (Non-Linear Area) was developed and implemented in RadiCAL to provide a simple, visual method to account for these self-equilibrating stresses that are readily ignored in pavement analyses. Top-down and bottom-up transverse, longitudinal, and corner cracking were found to be critical fatigue