DIY Concrete
Handy Hints
Have your job well prepared and well planned. Ensure your formwork is level and sturdy, this is important to ensure your concrete finish will be level and contained within your formwork. Lay plastic under the slab or wet down the sub-base to prevent moisture loss into the ground.
Before the agitator truck arrives have your equipment ready, shovels, rake, screeds, trowels, broom, wheelbarrows, gumboots, gloves, eye protection, helmets and sufficient manpower. Wet concrete is harmful in contact with your skin and eyes.
It is important to ensure good clear access, this will allow the agitator trucks to get to your job and manoeuvre around the site. It is far easier to pour the concrete directly from the chute into the formwork than have to carry it by wheelbarrow to the job. Plan your job to avoid delays once you commence pouring the concrete.
Decide on the type of finish you want for your slab, steel trowel, wooden float or broom, before you commence pouring. Do not finish your concrete before all the bleed or free water has evaporated. Working the surface too soon will weaken the surface.
Weather conditions can have adverse effects on concrete. On hot days (over 30°C) with low humidity and windy conditions you must control moisture loss from the concrete, spraying with aliphatic alcohol evaporation retardants after each working of the plastic concrete will assist in controlling moisture loss. Curing techniques such as ponding, covering with plastic sheeting and spray on curing compounds should be used. High winds and low humidity will induce faster loss of moisture from your slab resulting in shrinkage cracks. Intermittent wetting of your slab is not curing and can cause adverse results, increasing the risk of shrinkage or crazy cracking due to expansion and contraction. A continual spray of water should be used for proper curing of your slab. If you are not using plastic under your slab wet down the sub base, this will help reduce moisture loss into the ground. A dry sub-base will pull moisture from your slab helping to induce shrinkage cracking. Leaving formwork in place will also assist in retaining moisture.
Handling Precautions:
Prevent all contact with skin, wear gloves, long sleeves and trousers.
Prevent splashes entering the eyes, use safety glasses.
Use gum boots with sides high enough to prevent concrete from skin contact.
When using a concrete pump or crane kibble wear a safety helmet.
Plan your job well.
