Water is one of the most important elements in construction but people still ignore quality aspect of this element. The water is required for preparation of mortar, mixing of cement concrete and for curing work etc during construction work. The quality and quantity of water has much effect on the strength of mortar and cement concrete in construction work.
Quality of Water
The water used for mixing and curing should be clean and free from injurious quantities of alkalis, acid, oils, salt, sugar, organic materials, vegetable growth and other substances that may be deleterious to bricks, stone, concrete or steel. Potable water is generally considered satisfactory for mixing. The pH value of water should be not less than 6.
Effects of Bad Quality Water on Cement Concrete
It has been observed that certain common impurities in water affect the quality of mortar or concrete. Many times in spite of using best material i.e. cement, coarse sand, coarse aggregate etc. in cement concrete, required results are not achieved. Most of Engineers/Contractors think that there is something wrong in cement, but they do not consider quality of water being used. Some bad effects of water containing impurities are following.
Don't let this happen in your home. Use quality water for construction.
Caution: It has been observed at various places that cement concrete start falling down in pieces after rusting mild steel from RCC slab, which is due to use of bad quality/salty water in RCC slab. All this is due to negligence or ignorance which creates great problems and also bears a heavy loss. It is advisable that the water must be tested before using in construction work.
How to test water and what should be tested
It is recommended that the water is tested through a certified lab. The water should confirm the standard IS: 3025-1986 which is briefly described below.
Limit of Solids
It is a common thinking in construction work that the water fit for human consumption is generally acceptable for mixing mortar or concrete and curing work. However, the water must be tested before using in construction work. When you are making huge expenditure on construction work, a negligible amount spent on water testing should not be saved. Tested water or treated water should be used as this will increase the strength of cement concrete and enhance the life of building.
Treatment of Water: It is advisable that water should be tested in lab and if found unsatisfactory, it should be treated according to directions of laboratory. It is generally observed that ground water has some quantities of salt. In case of small work or in a situation where good water is not available, salty water must be treated with HCL @ 10 ml for 100 liters of water.
Quantity of Water: Water is an important component for mortar or concrete. The quantity and quality of water have much effect on the strength of mortar and cement concrete. It has been observed many times that in spite of using best raw materials, cement and tested water; concrete does not provide required results. Engineers/contractors think that there is something wrong in cement, but they do not consider water cement ratio or quantity of water added in the mix.
When the water is mixed in mortar, it reacts with cement and forms a binding paste which fills small voids in the sand. This creates a close cohesion of sand particles and cement. In case of cement concrete the voids formed between sand and coarse aggregate gets filled with the paste forming a cohesive substance/concrete. The required quantity of water is used to prepare mortar or concrete, but in practice it is seen that more water is mixed to make the mix workable. This is a bad practice and additional water weakens the strength of cement paste. Extra water also weakens adhesive quality.
Main disadvantages of mixing too much water in mortar and concrete
Hence strict control should be kept on water cement ratio for preparing the mortar or concrete for qualitative finish/ strength.
Quantity of Water for One Bag Mix
Water for Cement Concrete
Water Reducing Admixtures
The water reducer admixture improves workability of concrete/mortar for the same water cement ratio. The determination of workability is an important factor in testing concrete admixture. Rapid loss of workability occurs during first few minutes after mixing concrete and gradual loss of workability takes place over a period from 15 to 60 minutes after mixing. Thus relative advantages of water reducing admixture decrease with time after mixing. These admixtures increase setting time by about 2 to 6 hours during which concrete can be vibrated. This is particularly important in hot weather conditions or where the nature of construction demands a time gap between the placements of successive layers of concrete.
Hence in the area where there is less availability of water and the water is carried from long distances for construction work, the water reducing admixture is most beneficial for cement concrete work as it saves water up to 10%. It also increases the strength of cement concrete with the same quantity of cement.
Note: - pH Value: A method of expressing differences in the acidity or alkalinity of a solution. A figure of 7 is regarded as neutral; figures below this indicate the decree of acidity and above alkalinity.