The adverse weather conditions such as shrinkage and welling, freezing and
thawing, heating and cooling, exposure to high temperature and other
environments such as acids and sulphates during selection of material and method
of placing etc.**1) Consideration of secondary stress:**Due to the conditions
such as uneven drying and wetting, heating and cooling etc; the stresses are
produced and the magnitude of that depends upon element size, relative humidity
and ambient temperature. Hence for consideration of these stresses, the various
methods as well as codal provisions should be followed in the design of the
For instance, if mass concreting is done, it is good to use aggregate of low
thermal expansion coefficient to lower thermal strain in concrete because the
coefficient of thermal expansion of concrete as directly proportional to that of
- Appropriate selection of constituents:
- Capillary pores present in hydrated cement paste phase are very critical in
shrinkage and swelling of concrete element due to drying and wetting.
Stresses are developed when the water is absorbed during wetting and
evaporated during drying. Hence to minimize this, proper grades of
aggregates, smaller sized aggregate and low water cement ratio is used.
- In order to minimize the effect of the temperature stresses in the restrained
condition the aggregate having low coefficient of thermal expansion (e.g.
limestone) is used.
- To minimize the cyclic stresses developed in concrete due to freezing and
thawing air entraining agents are used and special mix design methods are
followed for use of these admixtures.
- Lastly, the Selection of appropriate reliant methods for concreting and
curing in hot and cold climatic conditions should be done.