Strength of Tension Lap Splices in Polymer Cement Concrete.

摘要

For the past 30 years an area of major concern to engineers has been the strength of spliced reinforcement in reinforced concrete construction. This investigation used an epoxy emulsion to form a polymer-portland-cement concrete (PPCC), which was cast around tension lap splices in reinforced concrete beams. The beams, with varying length of lap splice, were tested with the splice located in a constant moment zone. The results showed that the strength of the splice can be increased by as much as 50 percent in ultimate load carrying capacity by use of the PPCC. Calculations also indicate that the required development length of the reinforcing steel in the PPCC is approximately one-half of that in ordinary concrete. These conclusions do not reflect, however, the physical properties of the material. Although the test beams acted favorably, the tensile strength of the PPCC at age seven days was 602 psi (42.3 Kg/sq cm), which was only a 3 percent increase over the cement concrete. However, the average bond stress was calculated to have an average increase of 200 psi over the cement concrete. The PPCC exhibited a failure pattern which allowed the ductility of the member, even at short splice lengths, to be superior to that of the control beams. The investigation indicates that this type of construction can readily be adapted to field use without additional costs in labor and with a savings in time and steel over other types of polymer modified concrete. (Author)