If something goes wrong in construction, people often blame
poor quality of work execution, improper quantity of cements or non-gradation
of aggregates. However few elements of concrete also has some impact on the construction.
Water in concrete always gets least importance and often ignored by the
people at the time of construction. We should not forget that water is an integral
part of construction and any kind of compromises in quality of water during
construction may ruin all our efforts made at the time of construction. Water
is required for each and every construction activity whether laying PCC for
foundation or curing the concrete after completion of work.
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| (Image courtesy of Idea go /FreeDigitalPhotos.net) |
Therefore, you must
follow standard guidelines for deciding which water to use for construction work. Below I have
mentioned few of the important factors that must be analyzed thoroughly before using
water for construction purpose.
- Water should be free from acid, alkalis, oil, grease and paint to allow proper bond with concrete.
- Ph value of water should be identical to neutral level of 7.
- Water should be free from salt content and if excessive salt content is present in water then it should be treated with proper procedures.
- In general 27 degree Celsius is ideal water temperature for construction work and it is recommended to avoid extreme hot water for construction.
- Water should be free from organic and silt content and turbidity should not exceed to1.0 NTU.
- Avoid hard water for construction and post construction activity like curing.
Allowable water content for construction
Content
|
Allowable
Maximum value
|
Organic
|
200 mg / litre
|
Inorganic
|
3000 mg/ litre
|
Sulphate
|
500 mg / litre
|
Suspended Particles
|
2000 mg / litre
|
Chlorine
|
500 mg / litre
|
Apart from above, the most important thing that I have learnt over the
years that water is fit for drinking is appropriate for the construction
purpose.
Following is a list of some of the major problems that may arise,
if quality of water differs during construction.
- Water is an important element which helps cement in hydration therefore proper quantity of water/cement ratio should be maintained, excessive water in concrete leads to shrinkage and cracks.
- Presence of high iron content in water will develop cracks in the concrete surface.
- Excessive amount of water in concrete mix segregate the fine and coarse materials resulting in improper bonding with concrete.
- Hard water is harmful for concrete as it contains magnesium chloride, sulfate and hydrogen carbonates. However it harms concrete to certain extent but will corrode the reinforcement completely within the structure.
Concrete strength based on the water cement ratio
W/C Ratio
|
Concrete
Strength
|
.40
|
100 %
|
.50
|
90%
|
.60
|
70%
|
.70
|
50%
|
.80
|
45%
|
Best way to check the quality of water is by testing it in the
laboratory and if any objectionable content found then water should be treated
as per the IS guidelines. Moreover, specimen should achieve at least 95%
strength when compressive test is to be carried out.
You can also read my previous post on concrete curing compounds.
