Evaluation of high performance cementitious grouts for connecting precast concrete bridge deck panels

The use of full-depth precast concrete panels for rehabilitation of bridge decks allows fast installation and all-weather construction. Typically, precast panels are prefabricated in a well-controlled environment, resulting in strong and durable products. Undoubtedly, they will perform well under the traffic loading and weathering. However, the panel joints that are closed later with grout pour may degrade prematurely, leading to a less desirable composite action. Obviously, the lack of overall system performance causes concerns that limit the wider application of this innovative construction method. Conventionally, cementitious grouts, epoxy mortars or polymer concretes are used for the closure pour. In general, epoxy mortars or polymer concretes have extremely low permeability and dry shrinkage, as well as good adhesion with the substrate; but they are difficult to mix and clean, very sensitive to moisture variations, and incompatible with the substrate under thermal and mechanical loads. As a result, deficient bonding may occur, particularly when longitudinal post-tensioning is not provided, causing leaking and rusting. Oppositely, cementitious grouts are easier to mix and more compatible with the concrete substrate; however, they are more prone to shrinkage. More recently, advances in cementitious materials resulted in the development of Ultra-High Performance Concrete (UHPC). While this material has demonstrated exceptional performance when used for the closure pour; it requires special mixing to well disperse the particles and careful attention must be paid to the construction and curing practices to achieve enhanced mechanical and durability properties. As a result, testing of various types of grout materials is essential to establish the quality and serviceability of these materials. It is the intention of this paper to evaluate the performance of different cement-based grouting materials and to provide bridge engineers with useful database as to what materials are preferred for a specific project.