Why are lines etched in sidewalks when they're made?

Question

I always figured that lines were put in the sidewalk to give the sidewalk a weak spot to crack when the ground shifted, to make it easier to replace a section if need be, ,and for looks. The thing that confuses me is that sidewalks crack all over the place anyway! Especially where there's a meter box installed.

Answer 1

The "lines" are crack control joints; or control joints for short. Ideally, since concrete does crack these are an attempt to control where the concrete will crack rather than have random cracks. You're right though, sometimes it just cracks. Concrete is tricky in that temperature, slump, etc. all play a role in the final crack resistance.

Answer 2

Those cracks are called expansion joints and are engineered specifically for each job. They are necessary in any concrete project to allow for shrinking and expanding during hot and cold temperatures. Most of the cracks you are seeing are only surface cracks and won't affect the integrity of the concrete. These surface cracks could turn into larger cracks if it were not for the expansion joints. As luck would have it, it is not easier to repair concrete because it looks like they are in little sections, the expansion joints only go so deep. The ground should not shift under the concrete if the contractor has done his job when preparing the site. Concrete, even when dry and set, will continue to expand and contract. The little minut lines are put there purposely, yes - for traction, but its called a broom finish and are not cracks.

Answer 3

They are there for expansion purposes. They allow the concrete to shrink and expand with the temperature change. They are not there for easy section replacement at all. Some finishers just put a crease or a v-shaped "slot" or line across the concrete. Then some finishers actually cut a groove 2/3 of the way through the concrete to allow more room for more expansion. This will help prevent any cracking in the concrete.

Answer 4

What you always figured, is correct. They are called control joints. Some people call them expansion joints, but concrete don't expand. You may get cracks else where if the pad is not poured thick enough, or did not cure properly.

Answer 5

Those cracks are there to allow the cement to expand while drying and hardening. Im pretty sure when they lay the sidewalks there are no cracks for some period of time, but eventually wear and tear and age gets to the cement anyways causing those other cracks.

Answer 6

those are expansion joints where if the ground shifts under the concrete it cracks there but some times it dont

Answer 7

Sidewalks are created in blocks, the lines simply represents where one block ends and the new one begins... It does make it easier for individual repair.

Answer 8

they allow the concrete to expand and contract during temperature changes.. expansion joints

Answer 9

You're correct, they're for cheaper individual replacement. Also, notice the minute lines on concrete, for traction when wet.

Answer 10

I'm going to have to say that you are all RETARDED except for M M. He is the only one who answered correctly. I hope none of you breed.