STORING OF CEMENT
As cement is chemically very active with water, it is necessary to protect it from moisture during its storage till it is used for manufacturing the concrete. In the case of imperfect/long storage conditions, the strength of cement may reduce. The storing arrangement of cement should be such that cement delivered first can be used first and vice-versa. Generally, the cement is available in 50-kg bags, which are stored in stacks. At the large construction sites, the cement can also be stored in silos. These methods of storing cement and necessary precautions/requirements are explained in the subsequent sections.
Also, watch the video for a better understanding:
Storage of Cement at Site:
Storage of cement is necessary for uninterrupted progress of work. At site the cement be
stored properly so that it should not get in contact with dampness Cement bags should be stored on
a dry platform made of wooden planks resting on brick masonry, sand, aggregate platform about
150 mm above the ground.
- Fresh cement should not be piled over the previous lot
- Cement should be used on a first come first used basis.
- The number of cement bags is stored at the site according to their per day consumption,
- The piles of cement should be properly covered with tarpaulin sheets. These sheets must be properly overlapped and anchored.
- A temporary method of storage in wet weather should not be adopted.
Precautions to be taken in storing the cement:
- Do not stack the cement bags directly on the floors. They shall be placed on the dry wooden planks, which should be clear above the floor by 150 mm to 200 mm.
- Maintain a minimum all-round space of 450 mm between the bags and the external walls. A150, maintain sufficient all-round space between two adjacent stacks for proper movement.
- Place the cement bags in a stack close together so as to minimize the air circulation
- Restrict the height of a stack to maximum 15 bags so as to prevent the possibility of lumping up under pressure.
- Restrict the width of a stack preferably to 4 bags or 3 or meter or whichever is less.
- For the height of a stack more than that of 8 bags, place the bags lengthwise and widthwise in an alternate layer so as to minimize the danger of toppling over
- Stack the cement bags in a manner so as to facilitate their removal in the order in which they are received
- For storing the cement bags for a longer period or during monsoon, cover each stack with a waterproof sheathing
- Store different types of cement in different stacks.
- Number of bags stored on site should be such so as to be consumed on the same day.
- If more than 8 bags are to be put in a stack, then they should be arranged alternately as header and stretcher.
- Due to the weight on the lower layer of hags, the cement becomes somewhat hard which is known as the warehouse pack. This can be removed by rolling the bags when cement is taken out.
Storage of Cement in a Warehouse:
Always store cement at proper places where effects of moisture can be minimized. A warehouse is a weatherproof building for storage of cement.
Requirement of a Warehouse:
A warehouse must fulfill the following requirement:
- Walls should be constructed of waterproof material e.g., brick masonry in cement mortar with plaster on both sides.
- The roof should be made of RCC with proper drainage.
- It should have a few windows of small sizes.
- Windows should be constructed as near to the ceiling as possible.
- The floor should be of at least 150mm thick concrete.
- The floor should be at such a height that it should be at the same level as the truck height. will help in easy loading and unloading of cement bags.
- The ground surrounding the wall should be sloping always from the wall so that water is drained away properly.
Storing in Silos:
At the large construction sites where a large quantity of cement is required, the cement is preferred to be stored in silos. In silos, the cement can be stored in bulk i.e. 12-50 tonnes and that too under the ideal conditions. Silo is typically a welded steel cylindrical container. It is supported on four crossed braced legs and having a discharge outlet at the bottom. Moreover, it can also have some weighing arrangement at the bottom so as to get the required weight of cement in each batch Cement is supplied in close tankers from the factory and pumped into these silos directly from these tankers. Scoring of cement in silos has the following advantages as compared to storing the stacks:
- The cost of bulk cement per tonne is less than the bagged cement
- Unloading of cement through pumping arrangement directly into the silos is quite convenient and cheaper.
- Fewer precautions are to be observed.
- Less site space is required for any given quantity of cement
- As cement is delivered into the silos from the top and extracted from the bottom, the cement, which is received first, is always used first.
- The same silo can be reused for the other construction sites.
Effect of storage on strength of cement:
The cement stored at the site should not be laid for more duration. It should be consumed as earliest as possible. The strength of the cement decreases due to storage for a long duration.
Since due to the storage of cement there occurs a reduction in the strength of cement and so
cement should be tested in the laboratory before the start of Civil Engineering works.
The strength of the cement which has been stored for a long time should be checked in the
laboratory before it is used on important works.
Graph showing the reduction of the relative strength of concrete with respect to age.
The above pic for stored cement indicates that as the period of the storage of cement increases then the strength of the cement decreases and thus the rate of hardening of the cement concrete prepared with this cement is affected.
For more information visit: Site storage
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Also read: Manufacturing of cement