Concrete Mix-up

September 19, 2011 DevelopmentBG Other

The first thing you should do when you need to mix up a large amount of concrete is get yourself a concrete mixer. Doing it yourself by hand can be extremely laborious work so you should only consider this option if you are making up a small batch. Remember that concrete can cause alkali burns, so it is important that you avoid getting it on your skin or in your eyes (by wearing the appropriate gear when handling it; goggles and work gloves at the least). Mixers need to be positioned on ground that is reasonably flat, and because they can damage ground surfaces when switched on, you should cover any vulnerable floor with a sheet of plywood or something similar.

Your mixer needs to be placed near to a water supply and if you are mixing up a large volume of concrete you will require two people to make sure the work is completed as safely and efficiently as possible. You also need to check how much your mixer can handle at a time, because overloading it can cause damage and may be dangerous. Work out all of you measurements based on the mixer’s capacity. You should measure quantities using a bucket for more accurate results (than you would get with a shovel). Position the mixer drum at a 45° angle and start it up. Begin filling the drum from your bucket being careful never to put your hands inside or drop any tools in while it is running (as doing this would be bad).

Start with half of your sand and half of your ballast, then add water and allow mixing to continue for a minute or two. Keep adding water and mixing non-stop until the substance inside reaches the required consistency, which will be identifiable by the mix having the “right slump”. The right slump is achieved when the mix is not crumbling (when it is too dry) or slopping about excessively (when it is too wet), but when it is somewhere between the two in the Goldilocks “just right” position. You can usually tell by how far the mix moves around the drum as it turns; when it reaches the top of the drum before falling to the bottom it is too dry and if it doesn’t climb up the side at all it is too wet.

You need your concrete to be sufficiently workable to fill the entire void but to do so without air pockets being allowed to form. The right consistency of the mix is found when it climbs half way up the inside of the drum before dropping as the drum spins. When the mix does not have the correct slump, one of two things may happen. A mix that is too wet will not be able to adequately contain its mortar and will fail to set properly, while a dry mix simply will not fill all of the space in the void. When the mix is ready, get your wheelbarrow into position beneath the opening of the drum. Preferably, one person will hold the barrow steady while the other pours out the contents.

One member of the two person team should take the concrete to the site and use it immediately while the other begins preparing the next batch. Repeat as needed. Before finishing work or taking a break, you must thoroughly clean all of your mixing equipment or applying apparatus (if you want to ever be able to use them again). Clean the mixer by pouring a small amount of sand into the drum with water and let it run for a few minutes before you empty it. After this you should run it again with only water inside to flush out the remainder, empty it and switch it off. If the blades still need attention, you can use a stiff brush to finish the job. A stiff brush should do for cleaning off any shovels and barrows used, followed by a thorough hose-down.

Concrete walls and floors are considered to be non-standard risks by many insurers, so a concrete property is likely to be harder to insure than a conventional home. You can get non-standard home insurance from a specialist home insurance provider, even when other insurers refuse to cover you. Specialist house insurance is available to help people with unconventional homes or people in specialist insurance situations.

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