METHODS OF CORRELATING PRECAST CONCRETE SURFACE ROUGHNESS TO TENSILE BOND STRENGTH IN CONNECTIONS

摘要

This research project investigated three methods of measuring precast concrete surface roughness and the correlation of these measurements with the tensile bond strength developed in connections. Connections were represented with composite split cylinder samples composed of concrete and grout. The interfaces of each concrete surface were prepared to different degrees of roughness and measured using three techniques: the ASTM E965 Sand Patch Test, the International Concrete Repair Institute classification method, and a manual profilograph. Two types of standard concrete, a lightweight mix and a Virginia A4 mix, were used to represent precast concrete and a standard high strength, low shrinkage grout was bonded to the concretes to represent the cast-in-place connection material.rnThe composite cylinders were tested in tension along the concrete-grout interface using the ASTM C496 Split Cylinder Test. The strength of the interface bond for each cylinder was recorded and correlations were made to each of the roughness measurement techniques. The results showed the profilograph and sand patch techniques provided effective quantifiable roughness measurements while the ICRI technique provided a threshold roughness for better performance. A properly roughened interface could be identified with each technique and the tensile bond strength could be increased up to a factor of 3.5 when compared to a smooth interface.