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.

The testing program of reinforced concrete joints con-sisted of six beam column joints with varying strength cementing agents in the joint region: 1) normal strength concrete (fc' = 4,000 psi); 2) high strength concrete (fc' = 10,000 psi); and 3) polymer concrete (fc' = 12,000 psi). Half of these joints con-tained l-l/2 percent by volume of hooked end fibers. The polymer used in the joint region was Sika Stix 350. The fibers used were dramix fibers (30 mm. long by .50 mm. in diameter). From the test series on joints of this investigation, information on the following will be described: strength, ductility, energy absorp-tion and dissipation, mechanisms of failure, and mechanisms of stiffness and energy dissipation under cyclic loading. From the analysis of the results, it can be concluded that the polymer concrete used in the joint region provided: 1) better bond; 2) better confinement of the joint region; 3) a stiffer mem-ber; 4) a higher moment capacity; 5) higher shear strength; 6) more ductility; 7) far less cracking; and 8) significant improve-ment in the energy dissipation capacity than did the 4,000 psi and 10,000 psi portland cement concrete used in the joint area. The addition of fibers helped to strengthen the joint region, and improve the energy absorption and dissipation capacity of the joints with normal and high strength concrete. Also, the addi-tion of fibers to the beam column with polymer in the joint re-gion made made the joint area act elastically while the inelastic region was formed a distance 10 inches from the face of the col-umn in the normal strength concrete beam. The benefits and disadvantages of using a polymer concrete instead of high strength or normal concrete in seismic construc-tion of a joint will be described.

In the past a few years, greater interest has been focussed on the use of silica fume as a concrete admixture, which is a by-product in the manufacturing process of ferrosilicon and metallic silicon. The purpose of this study is to find appro-priate process conditions for developing superhigh strength concrete by the application of both silica fume addition and polymer impregnation. Base concrete was mixed by use of the silica fume and polyalkyl aryl sulfonate-type water-reducing agent, and cured in autoclave or hot water. The cured base concrete was dried, and impregnated with polymethyl methacrylate by thermal polymerization in hot water. The strength properties of such superhigh strength concrete were tested. The reproduci-bility of its strength development was examined. It is concluded that superhigh strength concrete having a compressive strength of 2370 to 2600 kg/cm2 is obtained by the above process with good reproducibility.

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.