Precast Prestressed Concrete Panel Subdecks in Skewed Bridges, Interim Report, 1990

Precast prestressed concrete panels have been used in bridge deck construction in Iowa and many other states. To investigate the performance of these panels at abutment or pier diaphragm locations for bridges with various skew angles, a research program involving both analytical and experimental aspects, is being conducted. This interim report presents the status of the research with respect to four tasks. Task 1 which involves a literature review and two surveys is essentially complete. Task 2 which involved field investigations of three Iowa bridges containing precast panel subdecks has been completed. Based on the findings of these investigations, future inspections are recommended to evaluate potential panel deterioration due to possible corrosion of the prestressed strands. Task 3 is the experimental program which has been established to monitor the behavior of five configurations of full scale composite deck slabs. Three dimensional test and instrumentation frameworks have been constructed to load and monitor the slab specimens. The first slab configuration representing an interior panel condition is being tested and preliminary results are presented for one of these tests in this interim report. Task 4 involves the analytical investigation of the experimental specimens. Finite element methods are being applied to analytically predict the behavior of the test specimens. The first test configuration of the interior panel condition has been analyzed for the same loads used in the laboratory, and the results are presented herein. Very good correlation between the analytical and experimental results has occurred.

Impact of Curling and Warping on Concrete Pavement, TR-668, 2016

Portland cement concrete (PCC) pavement undergoes repeated environmental load-related deflection resulting from temperature and moisture variations across the pavement depth. This phenomenon, referred to as PCC pavement curling and warping, has been known and studied since the mid-1920s. Slab curvature can be further magnified under repeated traffic loads and may ultimately lead to fatigue failures, including top-down and bottom-up transverse, longitudinal, and corner cracking. It is therefore important to measure the “true” degree of curling and warping in PCC pavements, not only for quality control (QC) and quality assurance (QA) purposes, but also to achieve a better understanding of its relationship to long-term pavement performance. In order to better understand the curling and warping behavior of PCC pavements in Iowa and provide recommendations to mitigate curling and warping deflections, field investigations were performed at six existing sites during the late fall of 2015. These sites included PCC pavements with various ages, slab shapes, mix design aspects, and environmental conditions during construction. A stationary light detection and ranging (LiDAR) device was used to scan the slab surfaces. The degree of curling and warping along the longitudinal, transverse, and diagonal directions was calculated for the selected slabs based on the point clouds acquired using LiDAR. The results and findings are correlated to variations in pavement performance, mix design, pavement design, and construction details at each site. Recommendations regarding how to minimize curling and warping are provided based on a literature review and this field study. Some examples of using point cloud data to build three-dimensional (3D) models of the overall curvature of the slab shape are presented to show the feasibility of using this 3D analysis method for curling and warping analysis.

Evaluation of Bond Retainage in Portland Cement Concrete Overlays Using Infrared Thermography and Ground Penetrating Radar, HR-537, Final Report, 1989

When concrete deterioration begins to occur in highway pavement, repairs become necessary to assure the rider safety, extend its useful life and restore its riding qualities. One rehabilitation technique used to restore the pavement to acceptable highway standards is to apply a thin portland cement concrete (PCC) overlay to the existing pavement. First, any necessary repairs are made to the existing pavement, the surface is then prepared, and the PCC overlay is applied. Brice Petrides-Donohue, Inc. (Donohue) was retained by the Iowa Department of Transportation (IDOT) to evaluate the present condition with respect to debonding of the PCC overlay at fifteen sites on Interstate 80 and State Highway 141 throughout the State of Iowa. This was accomplished by conducting an infrared thermographic and ground penetrating radar survey of these sites which were selected by the Iowa Department of Transportation. The fifteen selected sites were all two lanes wide and one-tenth of a mile long, for a total of three lane miles or 190,080 square feet. The selected sites are as follows: On Interstate 80 Eastbound, from milepost 35.25 to 35.35, milepost 36.00 to 36.10, milepost 37.00 to 37.10, milepost 38.00 to 38.10 and milepost 39.00 to 39.10, on State Highway 141 from milepost 134.00 to 134.10, milepost 134.90 to milepost 135.00, milepost 135.90 to 136.00, milepost 137.00 to 137.10 and milepost 138.00 to 138.10, and on Interstate 80 Westbound from milepost 184.00 to 184.10, milepost 185.00 to 185.10, milepost 186.00 to 186.10, milepost 187.00 to 187.10, and from milepost 188.00 to 188.10.