With self-builders now accounting for 10% or more of all new development, people are taking on bigger and bigger projects. With the help of online DIY guides and instructional videos, concrete pouring is becoming a more common home building tactic than ever before.
If you’re pouring concrete on your own, whether you’re an expert or this is your first time, you might want to consider common problems to avoid.
Here are five things to watch out for when pouring.
1. It Comes Out the Wrong Colour
When you’re mixing your concrete, if it’s well mixed, you’ll see everything as one colour. The right balance in your batch means that you’ll have a solid colour from your ready mix at the end.
Concrete discolouration can occur at the end when there are changes added at the end. Sudden changes or rushed operations creates discolouration because of improper chemical reactions. Some people add calcium chloride to their mix during the curing process, however, this will cause discolouration.
The ingredients that you mix together need to comply with standards set out by local authorities. Otherwise, you could be using something dangerous that isn’t suitable for use by the public.
If you want to avoid discolouration, you can take a few precautions to ensure that your concrete looks good when it’s done. Make sure that your subgrade is prepared in a uniform fashion. Then at the end, ensure that water has fully evaporated before you finish the concrete.
If you do hard trowel on the exterior of your concrete, you’ll end up setting the tone for changes to the colour.
2. A Scaly Surface
If you’ve noticed that the finished concrete that you’ve poured has a scaly surface that chips off and peels away, you might need to retry your efforts. If the surface breaks off and continues to peel away, it’s going to fall apart in no time. When air is introduced to your concrete, followed by freezing and thawing cycles, you could deal with scaling.
Scaling also occurs when the concrete isn’t strong enough to handle the weight that it bears. If you rush your curing process, you’ll end up with concrete that can scale as well.
Again, this problem can be avoided by ensuring that all the water on the surface of your concrete has evaporated before you work on it. If you add salt or additives during cold weather, you create the perfect conditions for scaling.
3. Watch for Crazing
Time and again, people pouring concrete deal with crazing. If you notice that there are sets of interconnected fine cracks along the surface of your cement, you’re dealing with crazing. If the cement paste rises to the surface and starts to shrink, you’ll be dealing with crazing.
While you’ll have perfectly strong concrete, these cracks will appear whenever your surface gets wet. This can give the appearance that your concrete isn’t strong. If looks matter to the client you’ve poured your concrete for, this can impact your end result and future projects with them.
Crazing occurs when you haven’t cured your concrete in as timely as a fashion as you should have. Moderates slump concrete without bleeding and segregation will help you avoid crazing.
Again, this is another problem that can be avoided by not working on the concrete until the water has fully evaporated.
Sprinkling water over your surface while there’s still water present can introduce crazing. Inversely, if you’re fighting the weather, which is causing fast evaporation, you might need to put some water on the subgrade. Otherwise, the subgrade will steal water from the concrete mix.
If you need to work fast, try using flowing concrete.
4. Cracking Is Serious
Cracked concrete is an inevitability of any pour. It can’t be fully eliminated. As the earth shifts and moves, as people use your surface, it’s going to be subject to cracks.
However, cracking can be sped up by the way that your concrete is mixed and poured. Cracking can result when the concrete shrinks as it dries. When the temperature changes drastically, contraction occurs, making cracks appear.
If you’re building a wall, cracks are dangerous, especially if it’s a load bearing wall. Be sure that the crack isn’t structural before you decide to repair it. You’ll need more drastic measures if the crack in the wall changes the structure or carries any kind of load.
You can avoid common cracking by preparing your subgrade. Get rid of the topsoil, organic material, or any soft spots in the subgrade. Make sure all the soil is compacted as much as possible.
If your subgrade doesn’t drain properly, it will keep water in and put pressure on the concrete to create cracks. If that water freezes, that extra volume will pressure the surface to crack.
Make sure you’ve got adequate concrete joints to handle the load. Follow the weather when you’re placing, finishing, and curing concrete. The environment that you pour concrete in matters a lot.
5. Curled Concrete Is Tricky
If there’s a big difference in temperature or moisture between the two surfaces of your concrete, you’ll introduce curling. The slab of concrete on top will then lose support from the base of the rest.
Make sure your concrete joints are places accordingly and use low water or water reducing mixtures. If you add enough steel reinforcements in your slab, curling shouldn’t be an issue.
On top of that, pour your concrete on a subgrade that’s slightly damp and absorptive. Your bleed water will then be leached downward and not forced to the top of your poured slab.
Concrete Pouring Is a Challenge Even for Pros
Whether you’re new to concrete pouring or not, you’re going to find there’s a lot of trial and error in using this material. You can do everything right and be undone by an unpredicted overnight drop in temperature.
Sometimes you can do everything wrong and still end up with a great pour.
If you’re considering using pumpable concrete, check out our guide for more info.