英语翻译In temperate marine climates away from direct sea spray

英语翻译
In temperate marine climates away from direct sea spray there is a slow accumulation of chloride within the concrete.In post-tensioned structures,attack on the strands themselves in this type of environment is rare.Provided that ducts and grout are intact there is little likelihood of corrosion of post-tensioned members in this type of environment.Tropical marine environments represent a much more severe type of exposure.Year-round warm temperatures help foster both the rate of ingress of the chlorides as well as the rate of corrosion itself.For pre-tensioned members to be durable over the long term in such environments it may be necessary to invest in high quality concretes having low permeability to chloride ions.F& post-tensioned members,the use of noncorroding ducts (such as polyethylene ducts) would help to halt the progress of chlorides towards the strand.Care must also be taken to protect the anchorage areas,such as encapsulation of the anchorage in impermeable material.
In deicing environments pre- and post-tensioned structures show susceptibility to corrosion at localized points on the structure.This can be at end expansion joints separating the deck slab from the approach slab,at joints separating the spans along the length of the bridge,through longitudinal spaces between adjacent box beams,and at anchorage zones in post-tensioned members.The actions of traffic and environment lead to joint failure,which allows deicer solutions to pass through the joint onto the pier caps and beam-ends in I-beams,and onto the sides of box beams.Installation of gutters and downspouts to carry deicer solutions safely off the deck,and careful joint inspection and maintenance can help to reduce the potential for corrosion in these structures.For posttensioned elements,it is very important that the grout fully encapsulates the tendons within the ducts,and that no potentially corrosive substances be added to the grouts.