The most important thing that a beginner needs to know about concrete is that it is acidic. The cement itself can cause chemical burns on exposed skin and even through clothing if wet concrete is not washed off when you get it on you. Along these lines it is very important not to get concrete into your eyes which is why wearing safety goggles is so important if you will be mixing, placing or finishing concrete. You will also want to wear a respirator mask when working with concrete to avoid breathing in harmful dust into your lungs. A paper dust mask is most commonly used when working with concrete however a full respirator with cartridge filters is ideal. concrete driveways sydney
Concrete Mix Ratios
In terms of working with the concrete itself the first thing you need to know is that the mix proportions are incredibly important. If you do not observe proper ratios in your mix the strength will be compromised and you will have unpredictable and undesirable results in the finished product. The most common mistake that someone new to concrete would make would be to add too much water to the mix. Over-watering is very easy to do since it takes very little water to go from too dry to too wet in a concrete mix. The actual amount of water needed to achieve the chemical transformation process that causes concrete to harden is in fact very little. A mix with the consistency of damp sand is more than enough water to set concrete. As you add water to a mix, the strength drops by a large amount as it is an exponential growth curve. For every small amount of water over the amount the concrete needs to set will reduce the finished strength dramatically. For this reason when a wet mix with high strength is needed, water reducers are added to the concrete to help achieve a workable slump for the concrete without compromising the strength of the mix.
Also integral to the mixing process is the fact that the better you mix the concrete, the stronger it will be. Under mixing the concrete can result in pockets where the cement and aggregates have not mixed together completely and this will cause weak points in your finished product. In a worst case scenario you can end up with an entire section of concrete that does not set up at all and remains wet.
Sunlight & Curing Speed
Be sure when working with concrete to observe heat and direct sunlight. Direct sunlight can cause concrete to set up and become hard ten times faster than when left in the shade. It is a common rookie mistake to leave your concrete unprotected in the sun for too long and cause it to start to turn before you have an opportunity to place and finish it – which leads us to the next point:
Do Not Re-Mix Concrete
A major mistake that many beginners make is to add water a second time to the concrete once it has begun to set up. This mistake often happens if you need just a little bit more or are having trouble finishing the amount that has already been placed. You can only add water to concrete one time. Adding water again after the concrete has started to set up will completely compromise the integrity, and likely prevent it from setting up at all. This is only true however for when the concrete is starting to set up and does not apply to the following 30 days after it has hardened.
Concrete Curing Fundamentals
Concrete takes a full month to cure to full strength and during this period of time it is very important to continue to keep the concrete wet. The catalyst that causes concrete to harden is the water, and after the concrete has set up it has used all the water available. By continuing to mist or wet down the concrete over the next 30 days, and most especially during the first week, will help to ensure that your concrete reaches the maximum strength possible.