Grades 53, 43, and 33 indicate the compressive strength of cement in Newtons for one mm2 area i.e., 53-grade means a compressive strength of 53 N/mm2 attained after a curing period of 28 days. Similarly, 43- and 33-grades may be defined.
The color of the cement depends on the raw materials used. If the raw materials contain more iron, the resulting cement will be darker. Color has no significance on any of the properties of cement. The strength of the cement is dependent on the correct proportion of raw material mix.
Slow setting in cement is due to salts and chemicals in water, sand, and aggregate, cold weather, less cement, a high percentage of impurities, adulterated cement, improper water-cement ratio. The quick setting of cement is due to the addition of a low quantity of gypsum, hot weather conditions, and high cement fineness.
When cement is mixed with water, alkali is released. Precautions should therefore be taken to avoid dry cement entering the eyes, mouth, and nose and to prevent skin contact with wet concrete and mortar. When working in places where dry cement becomes airborne, protection for the eyes, mouth, and nose should be worn. While working with wet concrete or mortar, suitable protective clothing should be worn such as long-sleeved shirts, full-length trousers. waterproof gloves and boots. Clothing contaminated with wet cement, mortar, or concrete should be removed and washed before further use. If cement enters the eye, it should immediately be washed out thoroughly with clean water and medical treatment should be sought without delay. Concrete or mortar on the skin should be washed off immediately.
- Do not store in a building where walls, roof, and floor are not completely weather-proof
- Do not store in a new warehouse until the interior is thoroughly dried out
- Do not make contact with badly fitted windows and doors and see that they are kept closed
- Do not stack against the wall. Always pile on the floor on wooden planks
- Do not forget to pile bags together
- Do not pile more than 10 bags high and arrange the bags in header and stretcher fashion
- Do not take cement from one-tier. Step back to three or four tiers
- Do not keep dead storage
- Do not keep bags on the ground for temporary storage at the worksite. Pile on raised dry platform and cover with tarpaulin or polythene sheets