Sometimes it may be required to perform cement quality tests at site within a very short period of time for evaluating the condition of the supplied cement. In most of the case it is not possible to have any laboratory test in short period of time. Therefore, quality check is performed with the help of some basic field tests. Although these tests are not very accurate, they provides some basic idea to the civil engineer regarding the quality of the cement.
Field Tests of Cement for Civil Engineers
- Date of Manufacturing: As the strength of cement reduces with age, the date of manufacturing of cement bags should be checked.
- Cement Color: The color of cement should be uniform. It should be typical cement colour i.e. grey colour with a light greenish shade.
- Whether Hard Lumps are Formed: Cement should be free from hard lumps. Such lumps are formed by the absorption of moisture from the atmosphere.
- Temperature Inside Cement Bag: If the hand is plunged into a bag of cement, it should be cool inside the cement bag. If hydration reaction takes place inside the bag, it will become warm.
- Smoothness Test: When cement is touched or rubbed in between fingers, it should give smooth feeling. If it felt rough, it indicates adulteration with sand.
- Water Sinking Test: If a small quantity of cement is thrown to the water, it should float some time before finally sinking.
- Smell of Cement Paste: A thin paste of cement with water should feel sticky between the fingers. If the cement contains too much pounded clay and silt as an adulterant, the paste will give an earthy smell.
- Glass Plate Test: A thick paste of cement with water is made on a piece of glass plate and it is kept under water for 24 hours. It should set and not crack.
- Block Test: A 25mm × 25mm × 200mm (1”×1”×8”) block of cement with water is made. The block is then immersed under water for three days. After removing, it is supported 150mm apart and a weight of 15kg uniformly placed over it. If it shows no sign of failure the cement is good.
Video about the field test of general characteristics of cement
The following video is collected from Youtube.com.