Behavior of the reinforced concrete at cryogenic temperatures

摘要

Concrete has successfully been used at extremely low temperature (-160 deg C) for the storage of liquefied natural gas. Such use will induce a cycle of cooling every time a container is filled. In addition, lack of control, as for example a leak may produce a sudden temperature change. Some knowledge of concrete properties under these conditions is therefore necessary for successful design and operation. The first and basic cause of the failure of concrete is repeated freezing (thawing) of moisture contained in the pores, microcracks, and cavities of the concrete. On transition to ice, water existing in the free state in cracks increases in volume, expanding the recess in which freezing occurs. A reduction in strength below the initial value is to be expected and further cycle of freezing and thawing have a further marked effect. The main objective of this paper is to describe the principal reasons for the reduction in strength and structural damage (frost damage) of concrete following repeated freeze-thaw cycles. Some experimental work was carried out at the Institute of Cryogenics, University of Southampton, UK, to determine what happens to water in concrete during the freezing transition.