TOO MUCH WATER ADDED TO THE CONCRETE MIX IS A RECIPE FOR DISASTER
In our experience, the most common cause for soft concrete in the UK is too much water being added to the mix and lack of/or refusal to cure the concrete after installation. Now, we get it - installing a dryer, strong concrete mix is quite a difficult task, especially when what is being laid is actually going be the finished flooring. Normally when concrete is laid it’s not going to be seen and therefore it’s not a big concern how it’s laid or how it looks. It will regularly be covered with carpet or tile.
It’s much easier for a contractor to put plenty of water into the mix so that the concrete flows into place without the need to be encouraged to get into the nooks and crannies by hand. Unfortunately, it’s this mindset that leads to a sub standard floor and less than successful results being achieved at the polishing stage.
One thing the concrete installer can utilise to aid his task is a super plasticiser or water reducing agent which offer extra workability without the need for more water. They also promote stronger floors and less cracking. At CARRcrete, we really do think they’re a pretty good idea!
Curing the concrete correctly is also incredibly important to ensure you end up with a strong hard concrete slab that is less porous and less likely to crack. We give full instructions on curing your concrete on our recommended concrete specification which you can request from us anytime.
Curing the concrete properly is not difficult. Simply wait for the surface bleed-water to evaporate then once it has, cover the slab with plastic sheeting that is secured at the edges to ensure no creases appear. What this does is stops the moisture within the slab from escaping too quickly. When this happens, the concrete is quite dry and has a sandy appearance, not the best substrate for us to polish.
If you prefer, you can also wet cure the slab which involves saturating the slab over a two week period. There are also certain curing membranes on the market but please do speak to us in advance if you’re thinking of using these. Some do present a problem to us when it comes to working on the floor.
One final point on curing. Concrete doesn’t react well to low temperatures so in the winter months it’s worth waiting until your premises are weatherproof and can be heated. A minimum temperature of 10 degrees C will produce good results.
Interior concrete will always have a superior hardness to concrete that is left to cure outside. This very rarely ends up optimal, even if it’s covered over.
