3. Concrete:-
• Concrete is a chemically combined mass which
is manufactured from binding materials and
inert materials with water.
4. Function of Water in Concrete:-
Three water serves the following purpose:-
1. To wet the surface of aggregates to develop
adhesion because the cement pastes adheres
quickly and satisfactory to the wet surface of
the aggregates than to a dry surface.
5. 2. To prepare a plastic mixture of the
various ingredients and to impart workability
to concrete to facilitate placing in the desired
position.
3. Water is also needed for the hydration of the
cementing materials to set and harden
during the period of curing.
6. • The quantity of water in the mix plays a vital
role on the strength of the concrete. Some
water which have adverse effect on hardened
concrete. Sometimes may not be harmless or
even beneficial during mixing. So clear
distinction should be made between the effect
on hardened concrete and the quality of
mixing water.
7. • Determination of Suitability of Mixing Water:-
• A simple way of determining the suitability of
such water is to compare the setting time of
cement and the strength of mortar cubes using
the water in question with the corresponding
results obtained using known suitable or distilled
water. About 10% tolerance is generally allowed.
Such tests are recommended when water for
which no service record is available
containing dissolved solids in excess of 2000 ppm
or, in excess of 1000 ppm. When unusual solids
are present a test is also advisable.