The tensile-splitting stress distribution for partially polymer-impregnated concrete is mathematically predicted from the viewpoint of theory of elasticity, and the results are confirmed by experiments. It is shown that tensile-splitting load to par-tially polymer-impregnated concrete cylinders can be predicted by the proposed failure mode and compressive strength can be adapted to the law of mixtures for composite materials. Furthermore the experimental equation proposed by Knudsen for the relation between strength and porosity for a porous brittle crystal body is examined. The obtained strengths for partially polymer-impreg-nated concrete can be evaluated more exactly than those heretofore in use.

Polymer concrete (PC) 3-in. x V-in. (75-mm x 300-mm) cylinders were loaded in uniaxial compression stress-strength ratios of 0.3, 0.4 and 0.5 for one year to investigate creep behavior. The PC was made with methyl methacrylate (MMA). The results indicate that the creep in PC is approximately one to two times higher than that of portland cement concrete. However, the specific. creep for both is about the same. The creep in-creases with an increase in the stress-strength ratio; but no linear relationship exists between the two variables. More than 20 percent of the final creep took place within the first day, and nearly 50 percent during the first five days. The static strength of PC was not significantly affected by the long-term creep loading. The high creep strain and the low sustained strength of PC could be the two major obstacles in its structural application. Plain PC 6 x 6 x 36-in. (150-mm x 150.-mm x 900-mm) beams made with MMA were tested to evaluate the flexural fatigue strength of PC subjected to different stress levels and stress ranges. The flexural behavior during the test period was observed. Beams were tested as simply supported beams with a 30-in. (750-mm) span and symmetrically loaded at third points. Beams were cyclically loaded at a constant rate of five cycles per second up to two million cycles or failure of the beam. Similar to port-land cement concrete, the applied stress is the most important factor influencing the fatigue life of PC. As the applied stress increases, the fatigue life decreases. The effect of the range between the maximum and the minimum applied stress was also significant; the wider the stress range, the shorter the fatigue life. Although the PC beam failed in a sudden, brittle mode, an increase in deflection was always noticed as the fatigue life was approached. The test results indicate that PC beams are superior to portland cement concrete beams in fatigue strength.

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.