An approach to characterizing materials related distress in portland cement concrete pavements

In recent years, there has been an increased awareness of materials related distress (MRD) in portland cement concrete pavements. These distresses include aggregate freeze-thaw, paste freeze-thaw, deicer attack, alkali silica reactivity, alkali carbonate reactivity, sulfate attack, and steel corrosion. This research presents an approach for identifying possible causes of MRD that draws on construction records, field surveys, and most importantly laboratory analysis. The analysis approach presented in this dissertation is being published as part of a series of guidelines prepared for the detection, analysis, and treatment of MRD in concrete pavements. These guidelines, and the proposed analysis approach, have been applied in the analysis of six distressed pavements with at least one pavement occurring in each of the four climatic regions established as part of the Strategic Highway Research Program (SHRP) Long Term Pavement Performance (LTPP) study. The results of applying the approach are presented. The centerpiece of the approach is a set of flowcharts that guide the analyst in asking questions about the distress that are intended to lead to discovery of the cause(s). Also, the flowcharts assist the analyst by combining a large number of resources regarding MRD into a simple to follow analytical process that can provide the best possible diagnosis of the distress. The guidelines will be most useful to engineers trying to correlate visual assessment and performance with the results of laboratory analyses. Although it is impossible to judge the absolute effectiveness of the analytical approach, the general effectiveness and usefulness can be qualitatively judged. The guidelines were found to be useful in steering analyses without stopping at the first distress mechanism identified thereby allowing for examination of all other possibilities. In every pavement examined, the guidelines led to useful, practical information regarding the nature of the distress. In all but one, an absolute identification of the MRD(s) present was obtained.