Fatal Factor for Durability: Drying Shrinkage - The Issues and Discussion of Modern Concrete Science - page 129

Fig. 11.1 Drying shrinkage crack emerging in an overpass in Xi ' an city

Generally speaking, generation of drying shrinkage is a slow process. In different
locations and environments, the emerging times are variable. Urumqi Airport in
Xinjiang done by the author in 2001, especially Hetian Airport done in 2003, which
are located at border of Taklimakan Desert, belongs to typical high temperature,
drying, and windy regions, and visible drying shrinkage cracks are both created in 2
or 3 years after accomplishment of the projects. In Southern China, it usually takes

five or more years to create visible drying shrinkage crack; in Northern China,
it may take 1

time. In recent years, as for effects of many reasons, many
projects in northern areas will generate drying shrinkage crack if they were under
the blazing sun for a week. The quickest crack can be created just after curing,
especially in summer (Fig. 11.4 ).
All in all, it is believed by the author that generating rate and seriousness of
drying shrinkage crack in concrete structure are increased in recent years.

5 years '

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11.2 Harmfulness of Dehydration Crack

According to field engineering experience of the author obtained for 20 years,

drying crack is usually quite shallow in southern humid regions, and it had no
signi cant effect on service secure and durability of engineering structure. It is also