Water quality is an essential aspect to consider when constructing concrete structures. Thus, various tests are conducted to ensure the suitability of water for such purposes. These tests are carried out in a laboratory setting and are performed according to clause 3.1.1 of IS 3025.
In civil engineering, a diverse range of materials are utilized in large quantities. To maintain the quality of the final product, it is crucial to subject these materials to testing based on predetermined patterns and within a desirable frequency of testing. This practice is particularly important in ensuring that the quality of the final product is maintained at all times.
Water Quality Tests for Concrete Construction
To ensure the quality of water for concrete construction purposes, several tests need to be conducted. These tests include pH value testing, limits of acidity testing, limits of alkalinity testing, percentage of solids testing, chlorides testing, suspended matter testing, sulphates testing, inorganic solids testing, and organic solids testing.
pH value testing determines the level of acidity or alkalinity in the water sample. Limits of acidity and alkalinity testing checks the water sample for acceptable levels of acidity and alkalinity. Percentage of solids testing assesses the amount of solid materials present in the water sample. Chlorides testing measures the concentration of chloride ions in the water sample, while suspended matter testing identifies any solid materials that are not dissolved in the water. Sulphates testing determines the concentration of sulfate ions present in the water sample.
Inorganic solids testing identifies the presence of inorganic materials, such as sand or clay, that may be present in the water sample. Organic solids testing assesses the level of organic materials in the water, such as leaves, algae, or other natural debris. By conducting these tests, it is possible to ensure that the water used in concrete construction is of suitable quality, which can help to ensure that the resulting concrete structure is strong, durable, and long-lasting.
Frequency of testing of water.
Water testing is a critical requirement before the start of any work. Therefore, water from each source must be tested at the outset. Additionally, the water must be tested once every three months until the work is completed. This is an essential measure to ensure that the water being used for the project is safe and meets the necessary standards.
It is important to note that water from a municipal source is subject to slightly different testing requirements. While water from other sources must be tested every three months, water from a municipal source only needs to be tested once every six months. This is due to the assumption that municipal water is subject to regular and stringent quality checks and is therefore safer to use.
Regardless of the source, each water sample must be tested three times to ensure accurate results. By adhering to these testing requirements, the quality of water used in the project can be guaranteed, minimizing any risks to public health or the environment.
Recommended Limits for Concrete Construction Water Tests
The water used for mixing and curing in construction must be clean and free from any harmful substances that may damage the bricks, stones, concrete, or steel. This includes substances such as alkalies, acids, oils, salts, sugar, organic materials, and vegetable growth. Potable water, which is safe for drinking, is usually considered suitable for mixing.
The pH value of the water must meet certain requirements to ensure that it is not too acidic or alkaline. For acidity, if it takes more than 5ml of 0.02 normal NaOH to neutralize a 100ml water sample using phenolphthalein as an indicator, then it is not acceptable. The test details are provided in IS 3025 (Para 22). For alkalinity, if it takes more than 25ml of 0.02 normal H2SO4 to neutralize a 100ml water sample using mixed indicator, then it is not acceptable. The test details are also provided in IS 3025 (Para 23).
The percentage of solids in the water must also meet certain limits. This is determined by testing the water in accordance with IS 3025. The maximum permissible limits for solids are provided in this standard. It is important to ensure that the water used for construction is of good quality to prevent any damage to the structure being built.
| Types of solids | Limits |
| Organic solids | 200 mg/liter |
| Inorganic solids | 3000 mg/liter |
| Sulphates | 400 mg/liter |
| Chlorides | 2000 mg/liter for concrete not containing embedded steel, and 500 mg/liter for reinforced concrete work |
| Suspended matter | 2000 mg/liter |
The tender documents for construction projects shall clearly state that the contractor must conduct tests on the physical and chemical properties of the groundwater and soil to ensure that the water conforms to the requirements of IS 456 – 2000. If the water does not meet these requirements, the contractor must provide good quality water from an acceptable source.
The water used for mixing should also be suitable for curing and must not leave any unsightly stains or deposits on the surface. Sea water is not acceptable for mixing or curing purposes.
Water from each source must be tested before the start of the construction work and every three months thereafter until the work is completed. In the case of groundwater, testing should be carried out at different points of drawdown. Water from each source must also be tested during the dry season before the monsoon and again after the monsoon.