The Effects of Spot Diamond Grinding PCC Pavements

The purpose of the research was to accurately determine the types and extent of problems created by spot diamond grinding on concrete pavements. Diamond grinding was first used in California, in 1965 on a 19-year-old section of I-10, to eliminate significant faulting. Since this first application, pavement grinding has grown to become a major element of PCC (Portland Cement Concrete) pavement restoration. The procedure is also used to insure a smooth ride on a newly constructed pavement. A comprehensive field survey was conducted to assess the conditions of selected spot diamond ground PCC pavement sites. Pavement surface distress data was collected on control and spot ground sections on 22 different highways consisting of 34 different locations in Wisconsin. In addition, micro-surveys of more than 2,200 pairs of slabs (ground and control) were completed for the spot ground sections. In addition, traffic volume data, pavement material properties and material and concrete cylinder tests results were collected for the selected pavement sites. The pavement sites were grouped according to their age, traffic volumes, material properties and material and concrete tests results. The PDI (pavement distress index) values and micro-survey results for each group was analyzed using paired t-test statistical analysis tool. The analysis indicated that the mean PDI values of the ground and control sections were statistically significantly different at the 95% confidence level. The 95% confidence interval for the mean difference is somewhere between 0.85 and 2.95. The distress indicators (e.g., Slab Breakup) mean difference between the ground and control sections were not statistically significantly different, except Distressed Joint/Crack. The analysis indicated that for Distressed Joint/Crack, the mean difference between the ground and control sections were statistically significantly different (at the 95% confidence level) and that the 95% confidence interval for the mean difference is somewhere between 0.0093 and 0.0267. Although the difference in mean is statistically significant, the practical significance of this difference is negligible, as it is smaller than the error in repeatability of the PDI procedures. The analysis indicated that, based on the micro-surveys, the mean values of the ground and control sections were statistically significantly different (at the 95% confidence level) for Distressed Joint/crack, Surface Distress and Longitudinal Joint/Crack Distress. For Distressed Joint/Crack, the 95% confidence interval for the mean difference is somewhere between 0.002 and 0.004. For Surface Distress, the 95% confidence interval for the mean difference is somewhere between 0.016 and 0.024. For Longitudinal Joint/Crack Distress, the 95% confidence interval for the mean difference is somewhere between 0.0006 and 0.0014. Although the difference in mean is statistically significant, the practical significance of this difference is negligible, as it is smaller than the error in repeatability of the PDI procedures. According to the analyses of the survey results for sections with low levels of dolomite aggregate mix, the mean values of the ground and control sections were statistically significantly different (at the 95% confidence level) for Distressed Joint/Crack and Transverse Fault data sects. This difference could not be considered negligible. Although statistically significantly different (at the 95% confidence level), for all practical purposes, spot diamond grinding does not adversely affect the performance and material properties of the pavement