Research is reported on the shear transfer between normal concrete and polymer modified concrete. The experimental program was designed to verify the general theory of shear transfer mechanism for concrete and to evaluate the necessary constants of the theoretical expressions. The general theory presented covers structural members with (i) no shear reinforcement, (ii) moderate shear reinforcement and (iii) high shear reinforcement. Four groups of specimens were tested. Group A specimens were used to investigate the relation between intrinsic bond shear transfer capacity and the strength of the composite materials (PMC and concrete). No transverse steel was used in these specimens. Group B specimens contained various amounts of shear reinforcement at the shear interface. Group C specimens were cast monolithically using ordinary concrete to serve as control specimens. Group D were control specimens made up of cast-in-place concrete over precast concrete. They were designed to evaluate the "apparent cohesion" of such elements, for the purpose of comparison with Group A specimens. The investigation will also present the extension of application of the theory to two-layered beams. Results of tests of 16 simply supported beams will be presented, where the principal parameter is the variation of the top PMC layer thickness. The major aspects to be presented are the load-deflection and cracking behavior, the mode of failure of the beams, the contribution of PMC to the strength of the composite beam, the initation and progress of slip in the interface of the two layers, frictional shear resistance of the unreinforced concrete-PMC interface, and the effect of using shear reinforcement to prevent any slip and shear failure.

Polymer impregnation and polymer concrete were used to repair the concrete roadway over the Bureau of Reclamation's Grand Coulee Dam. The equipment, materials, and processes used on this project are discussed in depth. The report includes data on the costs of the project.

P.C. (MMA) systems have been in use for over 20 years and have become one of the most promising materials for the rapid repair of concrete, especially bridge deck repairs. The major bridge applications include joint and spa11 repairs, thin bonded overlays, and deck impregnation. The latest design concept utilizing P.C. (MMA) is for modular bridge deck replacement using the P.C. (MMA) for bearing pads, for joining individual panels and for contraction joint pours. Pre-packaged systems consist of two components, a pre-mixed powder that contains fine aggregates coated with polymers, initiators and pigments and a liquid monomer component (Methyl Methacrylate). The practical success of the systems have been due to the application technology developed through applied research by commercial firms. Repair work with P.C.(MMA) is similar to work using Portland Cement Concrete and proper surface preparation is essential to the successful use of P.C. (MMA) for rehabilitation. P.C. (MMA), has many advantages over conventional concrete, including among others, rapid setting, ease of use, usability in hot and cold temperatures and water and salt resistance. P.C. (MMA) can also be feathered to "zero". There are several different P.C. (MMA) systems, each ideally suited for a particular application (i.e. thin overlays, spa11 repairs, etc.) and any questions related to its use should always be checked with the manufac-turer.

The quality deterioration of underwater concretes may be caused mainly by the washout of the cement from the concrete. The addition of an acryl-type polymer to concrete was found to be effective to prevent such deterioration. With the increase of the polymer content, the resistance of the concrete to be sepa-rated in water improved. This polymer did not affect the hydra-tion of the cement. A dialdehyde-type auxiliary agent was found to be effective to improve the function of the polymer at a dosage of only 1% of the polymer when it was added to the con-crete after the addition of the polymer. Due to the high vis-cosity of the concrete containing the polymer, the cleaning operation of equipment such as concrete pumps and mixers tends to be time-consuming. To avoid this, an alminum compound was found to be useful when it was added to the equipment together with water. Through the action of the alminum compound the concrete left in the equipment lost its viscosity immediately, flocculated and precipitated. By the field test in which concretes contain-ing polymer were applied to a underwater concrete structure, the performance of the polymer was confirmed.

The work presented is a portion of a larger investiga-tion concerning the improvement of durability of concrete structures in seawater. Therefore, as an introduction, the deterioration of reinforced concrete in corrosive environment is discussed followed by a description of two types of polymer modification of concrete. This latter means the addition of a liquid polymer of polymerizable system to the fresh concrete. The major portion of the paper presents a new investigation concerning the effects of epoxy modification on the properties of concrete, primarily strength. It is demonstrated that the addition of a suitable epoxy to the fresh concrete can increase the concrete strength significantly. This strength improvement can be further increased by the simultaneous use of a compatible superplasticizer, or an accelerator, or both.