Field Exposure Tests of Reinforced Concrete Beams

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Title: Field Exposure Tests of Reinforced Concrete Beams

Author(s): Edwin C. Roshore

Publication: Journal Proceedings

Volume: 64

Issue: 5

Appears on pages(s): 253-257

Keywords: air entrainment;beams (structural);deformed reinforcement;durablity;freeze-thaw durablity;reinforced concrete;reinforcing steel;research;testing;weathering

Date: 5/1/1967

Abstract:
Two series of reinforced concrete beams were made and exposed to severe natural weathering at Treat Island, Maine. Variables under study were type of concrete, thickness of concrete cover over steel and tensile stress in the reinforcing steel, position of the steel, and type of steel used. Results after 15 winters of exposure of the first series of beams (Series A) indicated that the air-entrained beams were significantly more resistant to the weathering than the non-air-entrained beams, and that the beams with reinforcing steel having deformations conforming to ASTM Standard A 305 were more resistant to the weathering than those with reinforcing steel having old-style deformations. These tests formed the basis for a change in Corps of Engineers practice in 1958 by which allowable steel stresses were increased from 18,000 to 20,000 psi (1260 to 1400 kg per sq cm). This change has resulted in a saving of cost in Corps of Engineers construction averaging $1.25 million per year since the change was made. Results after 12 winters of exposure of the second series of beams (Series B) indicated that more exposure is needed to produce deterioration sufficient to permit unambiguous conclusions. Exposure of both series of beams is continuing.