Hydrates hairline cracks are induced. Most pores are

Hydrates
are composed with water of crystallization in their structures. When a hydrate
is heated, it absorbs enormous quantity of heat (endothermic) and forms
anhydrous mineral. When an anhydrate is immersed into water; it absorbs water
and releases enormous quantity of heat transforming into a hydrate mineral 6.
In other way, it can be expressed that a hydrate is formed by releasing
enormous quantity of heat from its anhydrous product. For an example; the
formation snow from freezing water releases heat and snowfalls warms up the
atmosphere may be cited. The heat released into the pore space might promote
further evaporation of pore fluids. Most of the hydrates are stable and soluble
in water at room temperature. Some hydrates spontaneously loss water of
crystallization by efflorescence. Others absorb water into their structure
forming hydroscopic hydrates. Some deliquescent mineral like sodium hydroxide
absorb huge quantities of water and form as liquid. The decomposition of
carbohydrates generally releases water. Thus water of crystallization in a hydrate minerals play
critical role on their changes in their specific gravities and in turning their
volumes 7.
Hydration is not a reversible reaction; however, the environment
crystallization of hydrates plays critical role for the formation of hydrates
and anhydrates 8.  The repeated
hydration and dehydration changes the volume of saline minerals which in turn
affects the volume of pore spaces and hairline cracks are induced. Most pores
are partially or completely filled with saline pore fluids and repeated
influxes of saline fluids and evaporations play critical role on the evolution
of saline precipitates 9.  The
evaporation of saline fluids precipitates saline minerals initially at
peripheral portions of saline droplets inside the pores. The ionic components
of chloride, carbonate and sulphate, hydroxide and water play critical role in
the formation of mixed crystals of mineral components rather than individual
minerals. The scope of the investigation mainly lies to trace the trend of
changes of chemical composition during successive crystallization of chloride
components from the primary carbonate source. Generally, the composition of
groundwater is enriched with bicarbonates and depleted in carbonates. Similar
condition is true in the case of saline waters interlocked in the pore spaces
of lime-mortars.