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Cracked Concrete Blog Post

Hi Mike,

I have an older concrete driveway that is for the most part in good shape but there are some large cracks that run across it and I can see over the years that it is starting to lift. Is there anything I can do to stop this from happening?

Thanks,
Christine

 


 

Hi Christine,

There are two reasons concrete cracks…

The first one and more often overlooked is caused by shrinkage when the initial pour is made. Working with a concrete company and installers that understand the product as water in the mix relates to strength and shrinkage is key. Too much water in the mix causes the “cured” concrete to be much weaker at 28 days than originally expected. If water is used once the concrete is on the ground as a way of allowing a smooth finish, a separation occurs between the course aggregate and the fine sand, causing the cement to float to the surface. This creates an amazingly smooth appearance while there is no real bond on the surface. The winter freeze and thaw cycles will then pop the surface off. Using ice melting products furthers this problem and the result is called “Spalling.” There is no real repair to this that is quick and easy.

The second reason for cracking where there is shifting, is a problem with the base. There is either an insufficient base that is not compacted enough, or there is water in the base that isn’t draining out and away from the base area. The combination of concrete thickness and base isn’t sufficient for the loading. Most of our area in WNY has very heavy soils resulting in insufficient drainage.

To answer your question directly, there is not much you can do about your existing driveway in my opinion. The lifting is again caused by water and my suggestion is to make sure that is tackled when you are ready to do something new with the current surface. In the immediate check for water sources that are adding to the problem. Examples of this can be gutters unloading onto the surface, landscape or lawn areas trapping the water on or under the concrete surface, a broken waterline or even a sewer line.

Hope these answers are helpful,

Mike

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