Comparative testing by state transportation departments, universities, commercial testing laboratories, and precast manufacturers shows SURE CURE equipment outperforms sulfur-mortar capping as well as other reusable equipment. Cylinders capped with SURE CURE equipment consistently produce higher average strengths and lower coefficients of variation.
SURE CURE REUSABLE CAPPING EQUIPMENT
Hardware for the SURE CURE reusable capping system consists of two parts: (1) a steel retainer cap and (2) a neoprene pad. The pad fits inside the retainer cap and one such assembly is placed over each end of a concrete cylinder for testing.
Steel Retainer Cap. Each steel retainer cap is machined from a single piece of hardened bar stock. Caps are machined to exact dimensional tolerances. With reasonable care, the caps can be used indefinitely.
Neoprene Pad.All pads are manufactured by a molding process. Dimensions are precisely controlled so the pad fits snugly into the retainer cap. Three grades of reusable neoprene pads are available for testing concrete of all strengths:
Soft,for tests of 2000 to 4500 psi;
Standard,for tests of 3500 to 8000 psi; and
Hard,for tests of 7000 to 11,000 psi.
Neoprene pads can be used up to 100 times. SURE CURE equipment is available for capping standard 4 x 8-inch and 6 x 12-inch cylinders.
EXTENDED LIFE PADS
Ask about our new extended life pads made with higher quality material for greater pad life than conventional neoprene. If you are having problems with neoprene pads tearing up or not lasting long enough, then extended life pads are your answer. Many of our customers have reported that they more than double the number of reuses they get from a set of pads.
The reusable capping system substantially reduces the cost of both material and labor in testing concrete cylinders. Neoprene pads cost approximately the same per test as sulphur capping compound. With reusable caps the labor required to prepare a cylinder for testing is essentially eliminated, and testing can be done immediately. Cylinders capped with sulphur mortar require a two-hour set time prior to testing.
Retainer Cap and Pad
Both the American Society of Testing Materials and the American Association of Highway and Transportation Officials recognize the reusable capping system as an acceptable capping method (ASTM C1231-93, AASHTO T22).
Working with molten sulphur creates some obvious safety concerns. Sulphur fumes are extremely toxic, and molten sulphur can easily spill or splatter on workers, causing severe burns. The reusable capping system eliminates workers' exposure to the hazards of sulphur-mortar capping.
USE OF CAPPING EQUIPMENT
Before using SURE CURE capping equipment, we recommend purchasing the following items: (1) a supply of ordinary cornstarch and (2) a large grated-cheese shaker for dispensing the cornstarch. Cornstarch acts as a lubricant and bond breaker for neoprene. Proper use of cornstarch extends pad life and yields more consistent test results.
The following steps are suggested procedures to follow in the daily use of SURE CURE capping equipment:
Select the proper grade neoprene pad for the concrete being tested.
Generously dust all surfaces of the pads with cornstarch.
Insert one pad in each retainer cap. (It may be necessary to slide a small screw driver blade between the edge of the pad and the retainer cap to bleed the air from under the pad for proper seating.)
Set one of the capping fixtures on the bottom platen of the test machine (neoprene pad up). Sprinkle cornstarch on the pad.
Place the bottom of the cylinder to be tested into the capping fixture, centering it on the neoprene pad.
Shake cornstarch on the top surface of the cylinder until it appears white.
Place the top capping fixture (neoprene pad down) on the cylinder, centering the fixture over the specimen.
Carefully grasp the bottom capping fixture and cylinder and slide the assembly into the center of the test machine platen and proceed with test.
After testing, remove capping fixtures from broken cylinder and dispose of test specimen. Clean all concrete debris from capping fixtures and test machine platen before reusing the caps and pads for next test.
Note: SURE CURE capping equipment adds two inches to the height of a test cylinder. Some test machines may not have adequate clearance to accept 6 x 12-inch cylinders.
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