Can I still use my cement if some has gone hard or there are lumps in the bag? No, we would not recommend that any cement containing lumps is used. Lumpy cement will not create a homogeneous mix. There is also a good chance it may not gain as much strength as you would expect.
One common use of hardened concrete is to create embankments, terraces, or in other landscaping projects. If you're planning a garden makeover, consider using concrete bags as retaining walls or steps. Depending on the size of the project, you might use one hardened bag per step.
When mixed with water, cement undergoes a chemical reaction called hydration, due to which it hardens and acquires strength. This forms a major part of concrete's strength. The finer the cement, the more it hydrates (i.e., mixes with water) and gains strength.
We strongly recommend that you do not use any cement that has exceeded its use by date. The use by date on cement is related to health and safety regulations about 'chromium VI' which can cause allergic dermatitis.
One of the basic requirements to be observed is the expiration date and the storage period. The storage of cement is recommended for 30 days, which may increase this period by up to 60 days depending on weather conditions [3], as the expiration date is 90 days according to NBR 16,697 [4].
When a blemish appears on the surface of a concrete slab it will likely be one of these: blisters, cracking, crazing, curling, delamination, discol- oration, dusting, efflorescence, low spots, popouts, scaling, or spalling.
Can I still use my cement if some has gone hard or there are lumps in the bag? No, we would not recommend that any cement containing lumps is used. Lumpy cement will not create a homogeneous mix. There is also a good chance it may not gain as much strength as you would expect.
Yes, you can pour fresh concrete over existing concrete. As long as your concrete is in mint condition, this task is doable. If you decide to pour a new mixture over an old slab, be sure it is at least 2 inches thick.
Is there a shelf life for portland cement, or will it last indefinitely? A. If kept dry, portland cement will retain its quality indefinitely. However, bagged cement that's stored for long periods in a dry atmosphere can develop what's called warehouse pack, a mechanical compaction that makes the cement lumpy.
Old, unneeded concrete can be recycled and used to create recycled aggregate. In most cases, recycled aggregate will be used as a subbase material, but it can also be paired with virgin materials and reused as an aggregate in new concrete.
When the cement combines with water, the setting and hardening action results. This hardening can not be reversed. It is an irreversible process.
The inorganic compounds which are useful as concrete dissolvers generally include inorganic acids such as hydrochloric, phosphoric, hypochlorous and carbonic acid. Salts of these acids and alkalies such as sodium-hydroxide, sodium bicarbonate and ammoniumsulfate are also eifective.
Portland cement reacts with water to form an amorphous paste through a chemical reaction called hydration. In concrete the formation of pastes causes the mix to harden and gain strength to form a rock-like mass.
Vinegar does not dissolve concrete itself but can degrade the cement that binds concrete together. As a weak, dilute acid, vinegar will cause only minor damage to concrete but can take the shine off polished surfaces. It can, however, be used to remove small amounts of cement from tools.
Adding more water and mixing will possibly make it smooth again, but all those bonds that have started to form will be broken apart and will not form again. Of course many new bonds will form and the concrete will get hard again, but once it is over-watered it will never be as strong as it could have been.
CURING. The second state of concrete is known as curing, which is what helps concrete develop its strength and durability. Curing takes place right after concrete has been placed and finished. During this process, moisture and temperature are controlled for an extended period of time.
Fortunately, whether you plan to make a patio slab or a driveway, working in small areas divided by concrete forms and using bagged concrete mix can make the job easier for a DIYer.
Concrete that is not moist-cured at all dries too rapidly, and reaches less than half its potential design strength. It will also have a greater number of shrinkage cracks.
Contact with wet cement results in cement poisoning. This can result in dermatitis, skin discoloration of dark blue or red followed by fluid-filled blisters that can lead to open sores and even amputation. Prevention is key to avoiding cement burns through the use of personal protective equipment (PPE).
Yes, Cement loses its strength over a period of time.
When it absorbs moisture, it hydrates, and consequently the use of that cement does not contribute to the strength development or it contributes less. Such cement gets hardened and form lumps.
Ans : (c) Loss of strength of cement stored in bags in go downs for 3 months is about 15%.
Modern concrete—used in everything from roads to buildings to bridges—can break down in as few as 50 years. But more than a thousand years after the western Roman Empire crumbled to dust, its concrete structures are still standing.