Repair, Evaluation, Maintenance, and Rehabilitation Research Program Overlays onHorizontal Concrete Surfaces: Case Histories

摘要

This study documents the current practices for overlaying horizontal concretesurfaces as a first phase in the development of performance criteria for concrete overlays. The case histories presented were typically for overlays completed within the last 10 years and located at Corps of Engineers civil works projects. Overlays documented included bonded conventional, low-slump, fly-ash, silica-fume, polymer-modified, and fiber-reinforced concretes. Unbonded overlays were also documented. Although the information obtained for each case history varied and was sometimes limited, an attempt was made to provide the following basic information for each repair: (a) project description, (b) cause and extent of damage, (c) description of repair materials and procedures, (d) cost, and (e) performance of repair. The extension of service life resulting from using one type of overlay in lieu of another was not evident in the case histories examined, with the exception of where fiber-reinforced concrete was used to resist abrasion erosion (repair failed). Shrinkage and reflective cracks that develop in polymer-modified concrete overlays and overlays containing polypropylene fibers are more likely to be smaller in width and length than those of similiar cracks in conventional and low-slump concrete overlays. Cracks in concretes containing fibers are generally smallest.