Accession Number : AD0688879

Title :   TENSILE CRACK EXPOSURE TESTS.

Descriptive Note : Technical memo.

Corporate Author : ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS

Report Date : JUL 1955

Pagination or Media Count : 48

Abstract : Eighty-two reinforced beams were made of concrete with a nominal compressive strength of 3500 psi at 28 days age. Air-entrained and nonair-entrained concrete were used. Seventy-four beams were reinforced with rail-steel bars, of which 64 had deformations conforming to ASTM Designation A 305-50T and 10 had old-style deformations. Eight beams were reinforced with billet-steel bars having deformations conforming to ASTM Designation A 305-50T. Coverage over the steel was either 3/4 in. or 2 in. and bars were placed in either bottom or top position when the concrete was placed. Seventy-two beams were stressed from 20,000 to 50,000 psi by third-point loading and in the loaded condition exposed to severe natural weathering at half-tide elevation on the beach at Treat Island, Cobscook Bay, Maine. Ten control specimens were exposed but not loaded. Results after three winters exposure indicated that only air-entrained concrete specimens are sufficiently durable to withstand this type of exposure. Evaluation of the test results was based on the condition of the specimens after two winters exposure because of the rapid deterioration of the nonair-entrained concrete beams which constituted the majority of the specimens in the program. The test results indicate that specimens with bars having deformations complying with ASTM Designation A 305-50T performed more satisfactorily than did those with old-style deformations. No effects of depth of protective concrete over the reinforcing steel were revealed. (Author)

Descriptors :   (*BEAMS(STRUCTURAL), *REINFORCED CONCRETE), (*CRACKS, BEAMS(STRUCTURAL)), WEATHER, TENSILE PROPERTIES, MATERIALS, LOADS(FORCES), STEEL, DEFORMATION, STRESSES, DETERIORATION, CASTING, SHOCK WAVES, COMPRESSIVE PROPERTIES, MODULUS OF ELASTICITY, ENVIRONMENTAL TESTS

Subject Categories : Structural Engineering and Building Technology

Distribution Statement : APPROVED FOR PUBLIC RELEASE