Determining the influence of concrete drying shrinkage in the International Roughness Index of newly constructed rigid pavements in Bolivian Altiplano

In the last decade, the design and the construction of concrete pavements in Bolivia focused on prevention of fatigue damage of concrete by the design and construction of locally named "semi-short slabs" concrete pavements, a solution with slab size between traditional JPCP and short slab concrete pavements. Although the structural performance of these new pavements is adequate so far, it was observed that the length of the slab, which commonly is between 2.4 to 3.0 m, affects functional performance. Because of the slabs are affected by differential drying shrinkage, they develop permanent curling with wavelengths that have more influence on IRI with respect to other lengths due to the sensitivity of the Quarter-Car model. This article describes the studies conducted to determine the slab curling influence on IRI of concrete pavements built with semi-short slabs in the last years in the Bolivian Altiplano. Longitudinal profile data was collected by means of a laser profilometer in highway sections located in western Bolivia, in regions with high altitudes and arid climate. Based on profile information, mechanistic analyses were done in order to estimate the theoretical deflections along the slabs that correspond to the observed curling. Deflections calculated were then used to estimate a Pseudo Strain Gradient that represent the effects of curling along the evaluated sections. IRI related to slabs curling was calculated and compared to IRI calculated from artificially generated profiles for various slab lengths. Results indicate that slab curling of these pavements has an important influence on IRI of evaluated sections. Recommendations for specifications of new construction projects are presented.

Measurement and Analysis of Concrete Curling Slab Using Imbedded Sensors

A series of accelerated full-scale tests on rigid pavement were conducted to evaluate the concrete slab curling effects on the pavement design. Data from deflection sensors and embedded strain gages were acquired and analyzed along with the observed performance data. The collected data can be used for identifying the slab corner cracking and potentially giving the slab curling amount. Traffic tests were simulated using the finite element method in three dimensions and compared with sensor readings. A comparison of maximum tensile stresses between the curling slab and flat slab was performed. It was found that the critical stresses are located near the longitudinal joint in the curling model, the same as the distress observation of concrete slab.

Development of a Computer Model to Predict Curling of Poured Concrete Slabs on Grade

This paper addresses the causative factors associated with curling of concrete slabs poured on grade. The study was initiated when the owner of a newly constructed warehouse brought legal action against the designer/contractor for excessive concrete slab curling. Subsequent to settling with the owner, the designer/contractor brought legal action against the subcontractors who prepared the subgrade and placed the concrete. A computer model was developed by the defendant’s expert to evaluate the effect selected parameters have on curling of the concrete slab on grade. The parametric study was used to evaluate the most probable causes of the curling, which led to settlement of the case.