What makes sidewalks crack

As the root system grows and develops, these tips act as feelers, seeking out the path of least resistance for expansion. These pervasive little root tips can detect microscopic fissures in the concrete surface and, once they find one, the root pushes into the tiny crack.

The real culprit could be the bushes and trees growing near the cracked sidewalk. But, as with the cracks that are caused by weeds and small plants, the roots are not breaking the concrete without a little help.

Sidewalk lumps are the result of large root systems growing underneath the slab. This growth creates a hard point in the soil that is surrounded by softer dirt. Over time, constant foot traffic and extreme weather conditions cause the sidewalk to crack.

These cracks are carefully and evenly spaced before the first drop of wet concrete is poured and will help ensure the sidewalk is resistant to weather-relate d expansion or contraction. While these intentional cracks ensure resistance to weather-related stress and potenti al damage, concrete slabs will eventually develop cracks or other damage over time.

Weather tends to be responsible for most issues regarding construction, especially when it comes to concrete. Long-term exposure to just about any kind of weather will eventually cause materials to break down. In the case of concrete sidewalk slabs, this means cracks, sinking, and breakage.

These issues can also be the result of poor construction practices. For example, if the contractor did not properly prepare the soils that lie beneath the slab, voids in the soil may develop quicker and result in a cracked or sinking slab. Incorrectly blending the concrete mix and an improperly cured slab can cause a faster breakd own of the concrete, again resulting in cracks, breakage, or sunken slabs.

Thankfully, as much as we can rely on concrete sidewalks eventually cracking, we can also rely on solutions. There are a few options available for concrete sidewalk repair. The option that comes to mind first for many people is simply replacing the cracked slab. However, this option can be costly in both time and money, as the old slab must be removed and hauled away before a new slab can be prepped for and poured. A more cost-effective option is simply having the cracked concrete slab repaired via slab jacking.

If you're using concrete to make a sidewalk , the shrinking concrete will cause cracks to appear as it dries. To prevent sidewalks from cracking in random spots and breaking apart, builders make lines in sidewalks. Of course, they don't just call them lines. The technical term for sidewalk lines is contraction joints.

Contraction joints are placed in fresh concrete before the concrete dries and has a chance to create its own joints, which we call cracks.

As the concrete dries and shrinks, any cracks that form should follow the path of the contraction joints, since that's where the concrete is thinnest. If the cracks follow the contraction joints, the sidewalks won't look as bad. They also won't tend to form further cracks and break apart like they might if allowed to crack at random places. Builders place contraction joints in fresh concrete with saws, special grooving tools or plastic strips called zip-strips. They have to make sure that the joints are deep enough and made before the concrete begins to dry, so that cracks won't appear in the wrong places.

When you walk along the sidewalk, do you try to avoid the lines? Isn't it funny how we sometimes do things like that? Keep the learning moving along today by checking out one or more of the following fun activities with a friend or family member:.

We didn't spend much time on our poem, so we're sure you can do better if you use your imagination! When you're finished, grab some sidewalk chalk and write your poem on a sidewalk where others will see it.

If you would, please take a picture of your sidewalk poem and email it to us, post it on Facebook or tweet about it on Twitter. We can't wait to read what you come up with! After sharing your creation, check out some of Shel Silverstein's fun poetry and drawings from his book, Where the Sidewalk Ends. Hi, Ahmani! Way to go, Henry, we're so glad you learned something new with us today! Now you can Wonder as you travel along your neighborhood's sidewalks!

Thanks for telling us how much you enjoyed the video, too! We're glad to have an awesome Wonder Friend like you! Thanks for sharing your comment with us, Emma! We are thrilled that you learned something new with us about the sidewalks we use every day! Hey there, Rs11, we are glad you've been thinking about how sidewalks impact others!

Perhaps a smooth running path is a better route for a long walk! Thanks so much for your comment today, Sherry! We're super excited to hear from Wonder Friends who are also awesome educators!

Because of the age range of our different Wonder Friend visitors, and for the benefit of everyone who visits Wonderopolis and gains even MORE knowledge by reading over the comments to each Wonder, we occasionally have to adjust the spelling of a word or two, or help by adding punctuation.

We try very hard not to disturb the integrity of each comment's content, though. We value every authentic comment, and try our best to reply to each one. We're glad you stopped by Wonderopolis today! Your comment made our day, Team Unger 2! Thanks for stopping by this Wonder about sidewalks We're sure glad you learned all these awesome facts about sidewalks, Anne! It's pretty neat to learn new things every day in Wonderopolis, isn't it?

We really enjoyed your comment! Did you know there is a Wonder about the SUN already? We thought it was interesting to learn new things about sidewalks, too, Jenna!

Thank you for sharing this comment with everyone in Wonderopolis today, and also for guessing what you think tomorrow's Wonder might be about!

We can't wait to see if you are right! It's always good to take what you learn about something and strive to learn more, more, MORE! Thank you for leaving us this great comment today! We are so excited to hear about your sidewalk poems, Mrs. We will send good wishes for great weather! We like the video, too, Natalia! That little boy sure does like to hop a lot, doesn't he? Thank you for visiting Wonderopolis today! You'll have to check back to see if you were right! Thank you for hanging out in Wonderopolis today and leaving us a comment!

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Wonder What's Next? Try It Out When you walk along the sidewalk, do you try to avoid the lines? Keep the learning moving along today by checking out one or more of the following fun activities with a friend or family member: Get up close and personal with the sidewalks in your neighborhood.

You may have walked on them for years and years without ever really noticing them, but today you're going to get to know them. Get down on your hands and knees and examine the sidewalks in your area closely. Do you see the contraction joints?

How long are they? Bring along a ruler or measuring stick to do some basic measurements.