The cement should be stored carefully. Otherwise it may absorbed moisture from the atmosphere and may become useless for the structural work. Following precaution are to be taken for the storage of cement
(1). Moisture:
If moisture is kept away from cement, it is found that cement will maintain its quality for indefinite period. An absorption of one to two percent of moisture has no appreciable effect on quality of cement. But if moisture absorption exceeds five percent the cement becomes totally useless. Hence when cement is to be stored for a long period it should be stored in air tight containers.
(2). Period of Storage:
The loose cement may be stored indefinitely in air tight containers. But it is advisable to avoid storing off cement in jute bags for a period longer than three months. If it is unavoidable the cement should be tested to ascertain its properties.
(3). Piles:
The cement bags are stacked in piles. It is economical to form a pile of 10 bags of cement. A distance of about 300 mm should be kept between the piles of cement bags and exterior walls of building. The passages of width about 900 mm should be provided between the piles. For long storage the top and bottom of piles should be covered with tarpaulins or water proof paper.
(4). Quality of Cement:
The cement which is finely ground is more active and consequently it absorbs moisture rapidly from the atmosphere. Hence extraordinary precaution should be taken to store finely ground cement.
(5). Removal of Cement:
When cement bags are to be removed from piles of sufficient height the steps should be formed by taking out two or three bags from front piles. It is also advisable to remove cement in order of its storage period i.e. cement which is stored previously should be taken out first. In other words the rule of first in, first out should be followed.(6). Storage Sheds:
For storing cement for a sufficient long period the storage sheds of special design should be constructed. The walls, roof and floor of such sheds should be of water proof construction.
Few small windows should be provided and they should be kept tightly shut. The floor should be above ground. If necessary the drainage should be provided to drain water collected in vicinity of such shed. For determining the size of storage shed it is found that 20 bags or 10 bags of cement will require about 1 m3 of space.
It should be noted that cement even if stored in the most favorable conditions loses its activity when stored for a long time. For instance the storage duration of 3 months and 12 months will cause a reduction in the activity of cement to the extent of about 20 percent and 40 percent respectively.
Hence it is advisable to reactivate the cement stored for prolonged period. The most effective method of reacting such cement consists in vibro-grinding which ensure greater fineness and makes cement fit for use.
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