BONDING PROPERTIES OF 1/2 IN. DIAMETER STRAND

THE BOND-SLIP RELATIONS OBTAINED FROM SIX PULLOUT SPECIMENS AND SIX TENSILE BOND SPECIMENS ARE REPORTED. THREE COVERS OF 0.5, 1.0, AND 1.5 IN. (1.27, 2.54, AND 3.81 CM) WERE USED, THE STRAND BEING HELD HORIZONTALLY DURING CASTING. IN ALL CASES THE BONDSLIP CURVE COULD BE IDEALIZED AS ELASTIC-PLASTIC, THE BEING NO DETERIORATION IN THE MAXIMUM BOND STRESS WITH INCREASING SLIP UNLESS A LONGITUDINAL CRACK OCCURRED. FOR THE SMALL NUMBER OF SPECIMENS TESTED, THE SHAPE OF THE CURVE WAS FOUND TO BE INDEPENDENT OF THE METHOD OF TESTING, BUT THE MAXIMUM BOND STRESS INCREASED AS THE COVER DECREASED. THE AVERAGE DATA OBTAINED WERE USED TO PREDICT THE AVERAGE CRACK WIDTH AT VARIOUS STRESSES IN A TENSILE MEMBER. THESE RESULTS ARE COMPARED WITH THE AVERAGE CRACK WIDTH OBTAINED DURING EIGHT TENSILE MEMBER TESTS. THE ACTUAL AND PREDICTED SCATTER OF RESULTS ARE ALSO COMPARED. THE PREDICTIONS USING THE MOST ACCURATE FORMULA ARE GOOD; THE PREDICTIONS LOSE ACCURACY WITH THE USE OF SIMPLIFIED FORMULAS, BUT THE ERRORS ARE ON THE CONSERVATIVE SIDE.