The overall goal of this project was to evaluate with available cores the presence of alkali-silica reaction (ASR) in California bridges and pavements, to develop procedures for evaluation of ASR by Caltrans staff, and, potentially, to investigate several locations suspected of having ASR damage. This report summarizes the creation of an inventory for cores taken from bridges and pavements in previous projects, the results of visual inspection and strength testing to identify the potential presence of ASR, and the development of a draft approach for Caltrans staff to evaluate the potential for ASR in bridges and pavements. A spreadsheet database was prepared for storing inventory data for 265 pavement cores with four inch (100 mm) diameter and 311 bridge cores with two inch (50 mm) diameter. Most of the bridge cores were from the San Francisco Bay Area, while the pavement cores were collected from across the state. Visual inspection was performed on 259 of the pavement cores (including multiple samples from some of the pavement cores) and 80 of the bridge cores (those with lengths greater than the three-inch minimum required for evaluation of ASR) using the Damage Rating Index (DRI) method. None of the cores showed the likelihood of an ASR issue, as defined by a DRI greater than 2,000, although a few cores showed a small number of ASR features. Comparison of the ages of the bridges and the ASR damage rating index for the cores showed almost no trend, and showed no apparent differences between cores from bridges built before and after 1995, approximately when Caltrans changed specifications to reduce the risk of ASR. Most of the pavement cores tested had unconfined compressive strength (UCS) less than 8,700 psi (60 MPa) and the median of the UCS of the pavement cores was approximately 6,100 psi (42 MPa). Most of the pavement cores tested had densities less than 156 pcf (2,500 kg/m3 ) and the median of the UCS of the pavement cores was approximately 147 pcf (2,350 kg/m3 ). No significant correlation was found between the UCS and the density of the pavement cores tested, although the UCS strengths generally increased with increased density. The bridge cores were too small in diameter for strength and density testing. An integrated spreadsheet database was prepared for storing all relevant data for all cores, including test results from all tasks (DRI, UCS, and density). A draft guideline was developed for visual inspection of concrete cores to identify signs of potential ASR-related distresses and to support decisions regarding the need for a further detailed investigation for ASR. The guideline describes step-by-step inspection procedures and selection criteria for a further detailed examination, with relevant example pictures showing different severity levels of potential ASR distresses.

This study presented in this report is part of a long-term effort that started in 2005 to develop the specifications, guidelines, standardized laboratory and field test methods, and other information needed for quieter pavement research to be incorporated into standard Caltrans practices, and lead to quieter pavements. Based on an earlier laboratory study, several open-graded friction course (OGFC) mixes were selected for further evaluation with accelerated pavement testing using the Heavy Vehicle Simulator (HVS) and laboratory testing on plant-produced materials. These selected mixes had shown good overall laboratory performance in terms of durability and sound absorption, which is correlated with tire/pavement noise. Specifically, the following HVS test cells were constructed for this experiment: Cell A: Caltrans 3/8 inch mix with PG 76-22PM binder, average as-built thickness = 0.06 ft. Cell B1: #4P mix with PG 76-22PM binder, average as-built thickness = 0.06 ft. Cell B2: Same mix as Cell B1, average as-built thickness = 0.07 ft. Cell C: #4P mix with PG 64-16 binder, average as-built thickness = 0.05 ft. Cell D: Georgia 1/2 inch mix with PG 58-34PM, average as-built thickness = 0.15 ft The #4P mixes had nominal maximum aggregate size of 4.75 mm (#4 sieve) with “P” indicating a coarser aggregate gradation identified in the earlier laboratory study. The five test cells included three new OGFC mixes, with the Caltrans 3/8 inch mix serving as the control mix. The study examined the performance of the selected OGFC mixes in terms of their constructability, rutting performance, moisture damage susceptibility, surface texture, permeability, clogging susceptibility, clogging and rutting mechanisms, and tire/pavement noise. Recommendations are made regarding further work with the #4 mixes, and temperatures for OGFC construction. While all of the mixes are feasible for a given project, the preliminary indications with regard to differences in expected performance are: The #4P mixes offer superior noise and mechanical durability compared with the control mix. They have similar skid resistance as measured by Caltrans Test 342 (CST) and surface permeability. They have lower macrotexture than the control, but more than dense-graded mixes. A rubberized binder may improve moisture sensitivity and rutting performance, which were better or worse than the control mix depending on the binder type. The Georgia 1/2 inch mix is likely to provide superior skid resistance and rutting performance compared to the control mix, although it could not be fully investigated in this project due to difficulties in getting it produced by local plants as designed. This mix is also likely to cost more because of the lime treatment and fibers recommended by the Georgia DOT in addition to the polymer-modified binder. Based on the results from this study, it is recommended that several pilot sections be placed using a rubberized binder. For these mixes to be placed, the gradations may need to be adjusted somewhat to be producible using current crushed stone bin gradations. Consideration should be given to increasing the minimum surface and air temperatures for paving of open-graded mixes.