How to Avoid Unsightly Cracks in Your Concrete Slab or Driveway

Cracked Concrete

Have you ever been to someone’s house and seen cracks in their concrete floor or driveway and thought to yourself ‘this looks awful, how can I avoid this happening to my concrete’?

Well, without getting too much into the science of how concrete works, I’m going to let you in on some important tips about how to eliminate these unsightly cracks.

Base Preparation

Base to Concrete Work

With concrete a lot of it is about how good the actual preparation is. A concrete slab or driveway will only be as good as the base on which it is poured. Concrete needs to be poured onto a firm and compacted base. If the base is soft or has potential movement in it then this is likely to allow the concrete to crack through lack of support. The tip here is to make sure that whoever is preparing the base does a good job and doesn’t cut corners. This will help reduce concrete cracking.

Hosing down the base

Water is also very important when it comes to concrete. If concrete dries out too quickly then this leads to shrinkage cracking. With a driveway the concrete is usually poured onto a porous base. If the base is too dry, then this will usually mean that the moisture in the concrete is sucked into the base quite quickly which results in the concrete drive drying out too quickly and thus cracking. To eliminate this happening the driveway base should be hosed down with water to the point where it is just saturated. After this the concrete can be poured on top of the damp base and the moisture in the concrete won’t be sucked out into the base too quickly. Doing this will help reduce concrete cracking.

Reducing excessive wind exposure

With a concrete house slab the base is usually covered with polythene and is not porous so there is no need to hose down this base, however, another way that a concrete slab can dry out too fast is from excessive wind blowing across the top of the concrete while it is curing. There are a couple of ways to avoid excessive wind. One way is to try and block the wind with wind barriers. The other way is to use an anti-evaporation product such as ‘Sika Antisol A’, which is sprayed onto the concrete after it has been floated. This anti-evaporation product creates a film which stops the moisture in the concrete from coming out too quickly.
Doing this will help reduce concrete cracking.

Don’t add too much water

Don’t Add Too Much Water

Water is important when it comes to concrete, however too much water is also bad. With concrete there is an ideal water to cement ratio to produce a good result. If there is too much water put into the concrete mix this can result in shrinkage cracking when the concrete cures. An example of having excessive water is when a concrete pump is involved in the pouring process and the pump operator is not experienced enough so they add extra water to try and get the mix pumping through the line better. This happens often especially if there has been a hold-up. In this case a superplasticiser should be used rather than water. The tip here is to make sure there aren’t significant time delays that may allow the concrete to start curing early. If there are delays then use a superplasticiser. Doing this will help reduce concrete cracking.

In summary here are the tips to help reduce concrete cracking:

 
  • Make sure the base is firm and well prepared
  • Wet the base down with plenty of water before pouring concrete on to a porous base
  • Protect the new concrete from excessive wind exposure
  • Keep additional water to a minimum

Here at Goldline Construction we have been involved in residential construction for over 20 years. Over this time we have learned a lot of tips for getting a great end result. If you are considering building a new home or extending your existing home and want a great result, then contact us today. Let’s see how we can help you achieve the home of your dreams.

For more information about the different types of ready-mix concrete available check out this link
https://atlasconcrete.co.nz/ready-mix/

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