“Why are sidewalks, driveways, and curbs divided into sections when made with concrete or cement? #Construction #ConcreteTips
Have you ever wondered why sidewalks, driveways, curbs, and other surfaces made of concrete always have those lines dividing them into sections? Let’s break it down like you’re five!
##Dividing Concrete Surfaces
– **Prevents Cracking:** By dividing the surface into sections, it helps control cracking that can occur due to factors like temperature changes and settling.
– **Allows for Expansion:** The lines, also known as control joints, allow the concrete to expand and contract without causing damage.
– **Aesthetics:** The divisions create a neat and organized look, enhancing the overall appearance of the surface.
– **Ease of Repair:** If a section becomes damaged, it’s easier to repair or replace individual sections rather than the entire surface.
So, next time you see those lines in concrete surfaces, remember that they serve a purpose beyond just looking pretty! #ConcreteFacts #Construction101“
Concrete is going to crack. You can give it places to crack that don’t cause problems, or you can let it crack where it wants to. The dividing lines give the concrete preferred places to crack. That why they also sometimes put some fiberboard between sections of concrete so that there is a place for relative movement without cracking.
Concrete has thermal expansion… it gets bigger when it gets hot, and smaller when it is cold. The lines allow the concrete to move without cracking or buckling
These are called stress joints. Because of the weight and how brittle concrete is it is expected to crack, these joints are usually cut into the concrete to give the concrete a weak point so that when I’d does crack it cracks in an expected place. Sometimes these spaces can also be what is called an expansion joint to sometimes when a piece of new conrect is poured up against an old piece of concrete an expansion joint will be installed this is usually just a small piece of material set between the two slabs. These are the thicker black lines you see.
Perhaps this is a regional thing, due to climate. Where I live, in the UK, pavements, driveways etc can be a bit of a mixture of separate slabs or concrete, but it’s common for the concrete examples to be continuous over a large area.
For example, the road I live on had its pavements redone recently. It consists of long stretches of continuous concrete, maybe 20-30 metres at a time. It’s great for my daughter to skateboard on!
There are several reasons.
1. These lines, in climates where there is a lot of variance in temperature, allow the concrete some room to expand and contract from heat/cold, WITHOUT cracking.
2. If a crack DOES occur, the separation of the concrete into segments means that any crack that DOES form, is limited in how far it can travel. If your segment is 100 feet long, that means a crack can potentially grow to 100 feet long, meaning a repair or outright replacement of a 100 foot long segment, which is obviously more costly than, say, a 2 foot segment. This also prevents situations where, say, a conduit or drainage pipe collapsing will cause 100 feet of concrete to be entirely destroyed: only the slabs directly affected will break, while slabs that didn’t have ground shift underneath them will be fine.
3. Ability to remove discrete sections: say the city needs to replace a telecom conduit that runs under the sidewalk: if the concrete is just one big “slab” in 20 feet to the left and right of where you actually need to dig, this means damaging that entire 40+ foot slab, rather than being able to remove, say, 3 total 3×3 concrete slabs. This reduces the cost of future repair work (see 2) and also limits the amount of work needed for times when the concrete needs removed like this. You COULD crack open massive slab, do your work, then “patch” the broken slab with new concrete, but doing so is likely going to mean you’re going to get discoloration halfway through the slab AND the places where the old concrete and the new meet are going to be more likely to crack with the concrete generally used in construction.
Concrete (like almost everything) expands and contracts when the temperature change. IT doesn’t do it much; A one degree C warming makes it expand 0.001%. That doesn’t sound like much, but concrete is brittle, you can’t stretch or compress it much without it breaking. A sidewalk may be at -40°C in winter (up north) and in full sun in summer, could reach 60°C or more; a 100 degree swing. Places where it doesn’t get that cold in winter, could get even hotter in summer. Sidewalks also tend to be long, like kilometers long. A km of sidewalk will be (100°C * (0.00001 /°C) * 1000m) =0.1m or about 10cm longer in the summer than it is in winter. Having it divided into section breaks up that expansion into a lot of little gaps, instead of it trying to push the whole sidewalk. Another name for those are expansion joints.
Here’s an [image search](https://www.google.com/search?client=firefox-b-1-d&sca_esv=ab8b5e668a08de67&sca_upv=1&sxsrf=ACQVn092NxG4yRjtem_-7Tpd1eAJyIBOxw:1713950767528&q=sidewalk+buckling+in+heat&uds=AMwkrPtd7EXxieMQKehnHvZf8S6po8O8AsxKwTZqj0naF-RK2hAM72BGRNMfXZjKMbLhnGmi_UiSBRx3_WK9jb8hTcv-Yaek01k_hD3hEtq6MT0msXm2k69Dx26DuLmMFW6BZvdwVq5ehHtqJEdAfk8CAX-Q0DEc_RbwYbagfpyxOctPe03GhSpaPZV0PR6SYkbyqvLaXK_o1SL4YQ5410l-6LmLeGE5TBaJHZJqnEtWCI3vMGumPOx7r0YYSJHXCMpHMFYajbLURlURWMQ7mZ_lDXDlms4L7PrPxQKnyN2AazCTNg8hrAIiWlixO8Zyli3mb8XhZptJGaSKZ0CGlZU-35WgKx39EQ&udm=2&prmd=ivnsmbtz&sa=X&ved=2ahUKEwj9zaSVxNqFAxWmfzABHSJjBvoQtKgLegQIDRAB&biw=1318&bih=1302&dpr=2) for what happens if you don’t put in enough of those joints.
Depends on where you live. In my country (NL) the sidewalk, curbs, bike lanes and roads often all tend to be made of different materials and tend to be physically separated for increased safety.