The trick to pouring concrete on an incline, or slope, is to build sloping formwork. According to The Concrete Society, formwork is the wooden surround into which you pour the concrete. It retains the concrete until it has set, or cured. If your formwork is sloping, you can shape the poured concrete accordingly.
Build your formwork first by driving substantial wooden pegs into the ground in two gradually rising lines, representing the edges of the intended ramp. Use a sledgehammer for this task. Nail wooden planks to your pegs to create the shape of the concrete slope you would like to create. Fill the bottom of the formwork structure, up to about a quarter of the height, with hard core. According to The Concrete Society, you can use bricks, broken tiles, crushed rock, gravel and quarry waste as hard core.
Order your ready-mixed concrete from a reputable supplier. Ask whether their concrete meets NHBC and local authority standards. These standards are a reliable indicator of quality, according to Cemex.
Explain to the supplier you are building a concrete ramp. This will indicate that you need a slightly stiffer concrete mix, so it can be shaped easily, rather than running off. Give your supplier the measurements of your formwork -- length, width and depth at bottom and top of slope -- and she will be able to work out how many cubic metres of stiff concrete you need.
Tell the lorry driver any important details when the concrete lorry arrives on site. He will work out where to direct his chute for optimum pouring performance. He will probably start at the high end of the ramp, work across to the shallow end, then go back to the high end, to achieve an even pour.
Shutter off the concrete with the flat side of an old board as the level reaches the top of the formwork. Concrete naturally smoothes as you work it. If you want a rougher surface, so it is less slippery for people to walk on, turn the old board on its side and saw it across the smooth surface. This will leave a slightly rough texture when the concrete has set, which is ideal for giving grip.
Follow the advice of The Concrete Society and leave the concrete to “go off” -- or set -- for at least three days. Carefully remove the formwork, taking care not to chip the edges of the ramp. Build a handrail on at least one side of the ramp for safety.
Wear thick rubber gloves to protect your hands. Use kneeling pads to protect your knees. Wear goggles to protect your eyes from concrete splashes.
Tips and warnings
- Wear thick rubber gloves to protect your hands. Use kneeling pads to protect your knees. Wear goggles to protect your eyes from concrete splashes.