We have to acknowledge the fact that sidewalks are great places to play. For those who love riding a bike, a smooth sidewalk is much better than a bumpy lawn or a busy street. For those who love playing hopscotch or jacks, a sidewalk is a perfect place for it.
Most sidewalk are indeed made of concrete which is a manmade material unlike natural elements such as iron or aluminum. Concrete is made by combining cement, sand, crushed rocks, and water. Some think that cement is another form of concrete and that’s incorrect.
To be precise, cement is a special name given to a special type of material that firmly binds other materials together. So, it works in the same way as glue but with different materials and to a higher extent. Different types of cement can be used to make different types of concrete.
The moment cement is combined with water, sand, and crushed rock, a chemical process called hydration takes place. The result is a hardened form of concrete that is difficult to break. Concrete is solid form is equally as hard as stone. That is why we use it to make most of our constructions.
One of the main uses of concrete is to make sidewalks. Unfortunately, once it dries up, it tends to shrink a little bit. In case you are using it to make a sidewalk, it will eventually shrink and cracks may form once it dries up.
So, what happens is that, if you want to prevent your sidewalk from getting cracks, builders make what we call lines in sidewalks. There is a more professional and technical terminology for these lines is contraction joints. They get created in concrete that is fresh right before it dries up and begins forming cracks. Once the concrete is all dry the cracks will perfectly follow the path of the contraction joints because that is the thinnest part of the concrete.
If the cracks follow the contraction line, your sidewalks will always look good. The cracks will not extend and no parts will break away. What builders do is place contraction joints in fresh concrete zip-strips, special grooving tools, and saws. What they need to do is ensure that the joints are deep enough and designed way before the concrete begins the drying process to make sure that the cracks appear in the right places.