Start at the edge of the pile with the other person facing you. If you have someone to help you mix, it will be easier. Place the cement evenly onto the top of the pile.If there isn't much sand in the gravel, you can add some more Alternatively you may have gravel which is a composite mix of large and small stone and sand. Place the stone onto the ground followed by the sand.If you're using polythene sheet, spread it on the ground and weigh it down with blocks/bricks or whatever at the edges in windy weather.If you go for a C20 mix, a single mix using buckets ( which totals 7 buckets of material) is enough to produce a wheelbarrow of concrete. You can measure the proportions of the mix by counting shovels.
Larger quantities of concrete can be mixed on a flat surface on the ground around a post, the mixture can be a bit more sloppy so that it flows easier. If you are filling a hole in the ground e.g. If the mixture becomes too sloppy, add more cement. More water can be added until the concrete is at the required consistency. Water is then added, say half a pint at a time and mixed throughout the bucket. This needs to be thoroughly dry mixed with a garden or block layers trowel. If you need to mix a small amount, for instance half a bucket, place the stone and sand and finally the cement into the bucket. When mixing by hand, it is essential to thoroughly mix the concrete to get consistency throughout the mixture. In the US it is sold in 47 or 94 pound bags Mixing Concrete: Sand, Cement, Gravel, and Water Read the safety information on bags of cement! Buying CementĬement is generally available in 25kg bags. They normally also have a steel insole to protect feet from nails, glass or other objects that penetrate the outer sole. Steel toe-caps protect your toes from dropped bricks, blocks or rocks. You may end up standing in or close to concrete while mixing/laying.
This is because the underside of the slab would be spanning the individual stones of the sub base foundation and not supported underneath at every point over its full extent.
In reality a concrete slab would probably crack or sink with much less than this magnitude of load. In theory, this should make better concrete than rounded stone from gravel pits, because of the sharp angular edges. Ballast can have a varying proportion of sand/stone, so you may need to judge whether you have to add additional sand.Ĭrushed stone is produced in quarries by crushing blasted rock and then the result is graded by being passed through a succession of sieves. Instead of sand and stone you can use ballast (mixed aggregate or "all in") which is a mixture containing varying sizes of particles ranging from sand to larger stones. Premixed products from stores tend to work out much more expensive if you're going to need several wheelbarrows of concrete.
Your Options - Pre-mix Concrete or Make Your Own