Cement concrete is a very popular product, but it has a problem. Cracks can appear in concrete. They are not as common as people think, but they do happen. When they do, they can make the concrete fall apart and start leaking. This can cause structural damage to buildings, or even cause partial collapse of the building.
The good news is that there are things you can do about cracks: replace cracked areas with fresh concrete, fill gaps with fiberglass matting, add steel rebar to reinforce the structure, or replace the whole thing with newer cement concrete. If you have cracks from water seepage or other causes, those are not really problems for which you need to do anything.
A new product called VarioFiller is one way to fill in gaps and restore joints between pieces of concrete. It’s a high-tech version of a plaster application for getting rid of small cracks around windows and doors. It also works on large cracks in concrete and on surfaces that have undergone repair by other means (such as just patching over old damaged areas). However, it is expensive, and if it doesn’t work then your best bet is to tear up the surface and start again.
The number-one cause of concrete cracking is the water in the surrounding soil or ground water. If you pour too much cement and leave it too long, it may not have time to dry and set. This can result in cracks in your concrete. To prevent this from happening, make sure your concrete is properly cured, and that you are following proper curing procedures.
If you have a crack in your concrete, don’t panic. There are steps to take to repair the crack:
1) Make sure the crack is shallow and small. If it reaches down into the concrete, it will be difficult to repair without causing more damage than the original crack created.
2) Make sure that there is no moisture in the surrounding area where the crack exists. Dry out surrounding soil with a dehumidifier if necessary.
3) If possible, use a waterproofing compound such as Zinsser Seal Coat before you pour a new layer of concrete over the existing one. This will help seal any cracks that may occur so they do not become larger and more pronounced after being repaired by a new layer of concrete over the existing one
There are many ways a concrete structure can crack because of weathering or improper construction. Of these, the most common is by water seepage from an exposed aggregate or from the concrete itself….
Water infiltration into concrete structures over time can weaken the concrete and create weak points that allow for cracking. When this happens, cracks may become visible by small indentations in the surface of the material.
You can prevent water seepage into your concrete structure. These include:
1)Covering exposed aggregate with a waterproofing membrane such as Bituminous Membranes (BMS)
2)Limestone encasement to minimize permeability of the concrete material to water
3)Leaky concrete walls by adding a moisture barrier
If you want to understand the problem of cement concrete cracking, you have to understand how concrete works. For example, concrete is a mixture of water and cement. The cement in concrete is cementite. But there is no standard word for concrete; it’s different from project to project. So when you read a reference book or magazine article, you have to look at the table of contents or index to find out what kind of concrete it is talking about.
Water is mostly H20, but we sometimes mention here that there are other things in water besides H20, such as salt (NaCl). But even if that were not the case, water would still be mostly H20: it would always have about 97% H20. Some people would say 99%, but 97% or 99% doesn’t matter. You can’t count molecules of NaCl separately from molecules of H20: they are both still water molecules.
The reason why people use NaCl instead of plain old salt is that NaCl has other things in it besides Na and Cl: it also has anions like ClO 4 -, SO 4 2- , NO 3 – and HPO 4 2-. They are very small; they are part of the ions that make up the molecule Na+.
The most common cause of concrete cracking is excessive moisture. Water cannot break up cement, but it can weaken it to the point where it can crack. To avoid that, you must keep your concrete dry.
Dry concrete is a lot stronger than wet one. A lot of concrete is exposed outside, in parking lots or playgrounds or driveways. You don’t want to let it get wet where people walk on it. One way to keep dry is to coat the surface with a coating of bituminous material, such as asphalt or hot-melt asphalt.
But you can’t put too much asphalt on; you have to let the air get between the concrete and the asphalt so that no air bubbles form inside and burst later when they expand with water. If you do that, then the asphalt acts like a skin, protecting more of your concrete from moisture.
If you live in a cold climate, another thing you can do to make your concrete stronger is to use galvanized steel reinforcement bars embedded in the concrete. If an earthquake or traffic accident breaks through a wall and cracks the concrete, it will be less likely to crack all the way through if there are several steel bars in there, each holding together a few inches of concrete around its edges.
The good news is that concrete is not likely to crack. It has been tested and proven over the years. The bad news is that cement is hard to make, and in its current form it doesn’t work for all applications.
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