EFFECT OF SEVERE ENVIRONMENT ON CHLORIDE INGRESS INTO CONCRETE STRUCTURES Concrete under environmental loading

摘要

Performance of concrete subjected to aggressive environmental conditions is investigated in a full-scale laboratory exposure test. Concrete specimens are exposed to wetting/drying and heating/cooling cycles simulating the tidal zone of marine structures with daily temperature variations. In an attempt to integrate durability and structural design, the effect of "restraint" of thermal strains on the rate of chloride ingress into concrete has been evaluated by exposing the top surfaces of large beams, as "restrained" elements, and small cubes, as "unrestrained" test specimens, to the chloride environment. Other parameter studies include the curing conditions, cement type and temperature variations. The final results from a core drilling programme show that the temperature variation has a significant contribution to promoting chloride penetration into marine concrete. Concrete with blast furnace slag cement has found to be more resistant to chloride ions than portland cement regardless of curing conditions.