Technical director, Prairie Material Sales, Bridgeview, IL
Material Laboratory manager, STS Consultants, Ltd., Northbrook, IL
Sulfur caps were compared with unbonded polymer pads in compressive strength testing of concrete within the strength range 3000 to 18 000 psi (20.7 to 124.2 MPa). A less extensive study, still in progress, compares polymer pads with ground surfaces and lapped surfaces within the range of 13 000 to nearly 20 000 psi (89.7 to 138.0 MPa). Test cylinder size, 6 by 12 in. (152 by 305 mm) and 4 by 8 in. (102 by 203 mm), are included in this study within the strength range of 4000 to 18 000 psi (27.6 to 124.2 MPa). The results show that polymer pads result in significantly lower within-test variability than sulfur caps for strengths above 8000 psi (55.2 MPa). The ratio of 4 by 8 to 6 by 12-in. (102 by 203 to 152 by 305-mm) cylinder strengths ranged from 0.96 to 1.06. The strength differences due to cylinder size do not appear to be of practical significance for strengths within 4000 to 9000 psi (27.6 to 62.1 MPa). Grinding the ends of cylinders with strengths between 12 000 and 20 000 psi (82.8 to 138.0 MPa) shows promise as an improved test procedure for end preparation. Polymer pads appear to produce good test results provided the finished surfaces are smooth, which appears most significant within the range of 13 000 to 20 000 psi (89.7 to 138.0 MPa).
Paper ID: CCA10588J