Evaluation of Concrete and Mortars for Partial Depth Repair

Project summary:

There is an immediate and readily apparent need for a rapidly setting cementitious patching material for use in partial-depth repair. Partial-depth patching mixes must rapidly gain strength to allow the roadway to be reopened to traffic quickly. A patch should also bond well to the substrate to prevent the patch from separating from the existing material and be durable enough to withstand harsh winters. The objective of this research is to develop improved guidelines for evaluation of pre-bagged commercial patching mixtures and to recommend effective construction practices. To achieve these objectives, 13 different cementitious materials were selected and tested to determine key properties including strength gain, shrinkage, bond strength, and durability. The impact of the research is a better performing patch material and performance criteria that can be used to compare the materials tested in this program to new materials that will certainly be developed in the future. This research was conducted in four main phases: literature review and development of a testing plan and three phases of laboratory testing campaigns. The most commonly available acceptance specification for partial-depth patching materials is the ASTM C928. This specification was followed and the outcomes of each of the recommended tests were evaluated in context of the performance of the patching materials. Several additional tests were developed and conducted to evaluate the bonding properties of patching materials; correlations between lab measured properties were also evaluated. Through aforementioned testing and analysis, a laboratory testing based acceptance procedure was developed for partial-depth patching materials to be used by the Minnesota Department of Transportation (MnDOT).