A common issue among many beginners when working with concrete is adding too much water to the mixture. The ideal texture for most concrete applications is actually drier than most people think, so adding too much water to the mix is an easy mistake to make.
A concrete mix with too much water added has a number of disadvantages. It will cure unevenly, with water pooling towards the surface of the application. This can lead to cracking and spalling on the surface, as well as lower compressive strength for the finished product.
If you’ve mixed up a batch of concrete, and notice that it’s got too much water in it, is there a way to fix this problem?
I’ll break down what your options are in this situation, how to stop it from happening, and how to determine if your concrete mix is too wet in the first place.
How to Know if Your Concrete Mix is Too Wet?
Water is a key component in any concrete mix. It’s not just there to create a workable consistency, but it actually activates the cement inside the mix to begin the chemical reaction of bonding the cement with the aggregate.
That said, it’s important to use the ratio of water to the concrete mix. The exact ratio will depend on the specific type of concrete mix, so it’s important to follow the instructions on the back of the concrete mix bag.
A typical mix is about 10 to 15 percent cement, 60 to 75 percent aggregate, and 15 to 20 percent water.
When the water has been added, and the mix sufficiently stirred, the concrete should have the texture of wet sand or dry mashed potatoes. You’re not looking for soupy textured slurry, as this amount of moisture will weaken the final product.One way to test the concrete is by scooping up some concrete with your trowel and sliding it off. When you scoop up the mix it should stay on the trowel and not slump excessively. When you shake the trowel, the concrete should come off cleanly with little to no mixture sticking to the trowel.
Another method is the concrete slump test. This is a consistency test used by concrete professionals upon delivery of a batch of fresh concrete from a truck.
The basic idea is concrete is poured into a cone-shaped metal mold known as a slump cone. If the concrete collapses or slumps excessively then the mixture may be too wet.
Effects of Excess Water
The effects of excess water in a concrete mix are numerous and detrimental.
Too much water in the mix means you’ll end up with more water than is needed for the chemical reaction to take place. This means water will be retained inside the concrete even after drying.
This water can form small cracks over time as it eventually evaporates, reducing the concrete’s compressive strength.
Water has a tendency to pool on the surface of drying concrete, which is referred to as bleed water. This is a clear indication that you’re concrete has too much water in it. This will lead to spalling and cracking on the surface, creating a poor-looking final product.
All of this essentially results in a less durable concrete application.
How to Fix Too Much Water in Concrete?
If you have a batch of concrete with too much water in it, then don’t be so quick to give up on it – chances are you can fix it with a little effort.
If the batch is freshly mixed, then simply add a small amount of dry concrete mix into the mixture and stir it around until it’s reached the right consistency. Make sure to only add a small amount at a time, as you don’t want to dry out too much either.
If you’ve ordered concrete from a supplier, and it’s too wet, then you can simply return the batch and ask for a better one. Be aware though that concrete from a truck sometimes is designed to be wetter and has special additives in it to allow it to retain water but not compromise the final product.
Lastly, if you’ve already laid down a slab and it’s begun to dry, and you notice bleed water on the surface then you can clean up some of this using rags or even a pump to drain this water. At this point it’s typically too late to add more dry concrete to the application, so chances are you’re going to have some degree of weakness from too much water.
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