One cannot think of concrete without cement. Cement is the most essential material used in the production of concrete or mortar. Cement is a standard construction material that is widely used in modern construction. However, it is possible that some cement stored during the construction of large-scale projects will expire over time. “Can I use old cement”? One wonders in such a case. Gharpedia answers this query.
Concrete or mortar is a mixture of cement, aggregates, chemical admixtures and water. During the mixing process, cement reacts with water and generates heat through hydration. This process is also known as the ‘hydration of cement’, which plays a vital role in gaining strength. The strength of cement is directly related to the strength of concrete, as well as the life of the structure.
Fresh cement is a fine hygroscopic powder that quickly absorbs moisture from the air. The hydration process starts when the cement bags absorb moisture from the air, and the cement will gradually lose its strength. A small amount of moisture is always present in the air, which aids the hydration process in the cement bags and slowly causes some initial setting. The strength of cement decreases over time as a result of this process. In general, the shelf life of a cement bag is three months.
When fresh cement is stored for a longer period of time, it gradually loses its strength. Bethel Getachew, Tamene Adugna and Sintayehu Assefa conducted a study on the effect of storage time due to the moisture absorption of cement on the properties of concrete. A reduction of 22% in the strength of concrete is observed when it is made from cement that is 3 months old, as compared to concrete made from fresh cement. If the cement is left unused for a longer period of time, the setting of cement takes place due to atmospheric moisture and in the process cement loses strength. That cement when used in concrete or mortar, the concrete or the mortar does not gain the desired strength. The strength of the cement, which has been stored for a long period of time, should always be checked before it is put to important use.
Note that generally, cement not more than three months old can be used without testing. It is recommended that the cement should be used within three months from the date of manufacture.
How To Check Whether the Cement is Fresh or Not?
Cement is a very fine material packed in jute/plastic bags. When it gets older, lumps are observed in the bags, which develop due to the reaction between the fine cement and the atmospheric moisture. We have a detailed guide on how to check the quality of cement on site:
In a cement warehouse, fresh cement bags are stored or placed in such a way that the old bags are used first and then the fresh ones. Storage of cement bags in bulk in a warehouse has a rule called “first in-first out” It means the older bags go out first for their use.
Cement bags are stored in a safe warehouse, where they have lesser chances of reacting with air moisture. As a result, they remain fresh for longer periods of time and do not lose strength over time. Therefore, the storage warehouse should be well-prepared to store the cement.
Can I Use Old Cement?
If you have bags of cement with an expired shelf life, then you should avoid using them. Remember that if you use old cement bags, you may never achieve the desired strength. Hence, such old cement should be disposed of, or it may be used for non-structural purposes, such as in plain cement concrete (PCC), mortar for flooring, plaster etc., in a slightly higher proportion. Of course, this can only be done with the permission of the engineer-in-charge or the architect and only after thorough testing.
To keep cement fresh, the storage of cement bags must be done appropriately.
How To Store Cement?
Proper storage of cement is important to keep it fresh. Hence, you may wonder how to store cement. To keep the cement as fresh as possible, keep in mind the following points:
- Keep cement in a dry, leak-proof, and moisture-proof environment. Doors and windows must be kept closed.
- Bags must be stacked on a wooden plank or on a strong tarpaulin at least six inches above the ground. Bags must be stacked at least one foot away from the walls.
- The width of the stack must not be more than the length of four bags or three meters.
- The stack’s height should not exceed 10 bags.
- Bags must be kept close to each other to prevent the circulation of air.
- Cover the cement with tarpaulins or plastic sheets during the monsoon season or when it must be stored for an extended period of time.
- HDPE and paper bags must be stored separately.
- Do not use hooks to lift cement bags.
- Always use cement in the “first in, first out” method.
We have a detailed article on how to store cement. Make sure to check it out:
What to do with Hardened Bags of Cement?
Cement will harden faster during the monsoon season. However, keep in mind that cement begins to deteriorate approximately three months after production. Hence, it is best to use cement within three months of bagging. If you need to use cement more than three months after it was manufactured, always test it first to ascertain that it is fit for use. However, if the cement has hardened in the bags, several questions arise, such as what to do with hardened cement or what to do with old cement. One of the most common uses for hardened concrete bags is for landscaping projects, such as forming terraces or embankments. You can also break up the bags’ contents for backfill when levelling slopes or filling large holes or dips in your yard.
Different Tests to Check Quality of Old Cement
If you happen to have a bag of cement with expired shelf life, you must test it before using it. There are many tests that are conducted on old cement to determine its strength and quality. The most basic is to look for lumps and see if the cement is floating freely on the water. The presence of lumps indicates that the cement is unfit for use. If the cement is not freely floating on water, this again means that the cement has deteriorated. However, some other common tests are:
- Fineness test (sieve test)
- Consistency test
- Setting time test
- Strength test
- Soundness test
- Heat of hydration test
- Tensile strength test
- Chemical composition test
Finally, in response to the question, “Can I use old cement?” never use expired or outdated cement to construct a house or any important structure. Always check the shelf life of cement before using it. To ensure high-quality construction, use lump-free and fresh cement. Good cement results in a safer and longer-lasting house. It will also save money that would otherwise be spent on repairs and maintenance.
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