Mortar and Concrete Mixes

!±8± Mortar and Concrete Mixes

I suppose a lot of folk think that mortar and concrete aren't really worth writing an article about--after all, you just mix them, and get on with the job that you're going to use them for. However, different jobs require different materials, and different quantities of those materials. The guide here is one that I've followed successfully over the years, and I hope it will prove beneficial to you as well. As weights of sand and ballast or quarry chips etc. vary due to their water content, the following guidelines are given by volume.

For a concrete path use 1:5, where 1 stands for ordinary dry cement, and 5 is for the sand and ballast. For concrete steps, make the mix maybe a bit stronger, 1:4. If you're laying bricks, it's 1:4 (soft sand). For rendering, use 1:4 (2 fine-washed and 2 soft sand). If you're doing a floor screed, it should be 1:3 (sharp sand). Additives are available for many tasks if required. Plasticiser is excellent in mortar, but be careful not to use too much. A frost proofer can help if the temperature drops to around the zero mark, although I prefer not to work with cement if it's that cold, just to be on the safe side. If it is cold or damp, you could use an accelerator to speed up the drying time to about an hour, although I must admit that I like it to dry naturally. For rendering, you'll need a waterproofer in the first coat, so that it doesn't bridge any damp proof course. You'll also need it if tanking a basement.

For tools, you should use 2 shovels--one for the dry stuff, the other for the wet. You'll need a couple of buckets, a trowel, a garden hose (an outside tap is very handy), a board (if mixing by hand), and a wheelbarrow.

If you have a fairly big job, you're better off with a mixer, hired if you don't own one. If you have one that sits on a stand, make sure it's properly chocked before you start it. Put in most of the water first, then half the ballast, leave turning for a couple of minutes, then add half of the cement. Pour in the rest of the water, add the remaining ballast and cement, and leave to mix for about three minutes. You should then find that the concrete falls smoothly off the blades. Tip the mix into the barrow while the mixer drum is still turning. Pour water into the mixer to help cement from drying on the sides--this water is then handy when you start your next batch. When you've finished with the mixer, make sure you give it a proper clean, both inside and outside the drum. I remember my first boss telling me that I should be able to drink the water out of it if I'd done the cleaning properly. I tend to remember this when cleaning any tools.

If it's a smaller task, you can easily mix the required amount by hand. Place the sand or sand/aggregate on a board or similar hard, even surface. Add the dry cement and mix well, using a square nosed shovel (as distinct from the round mouthed). Form a well in the centre by pulling the dry mixture out on all sides. Pour in half of the required water and any additive that you want to use. Gently prod the dry ingredients into the liquid, and start turning it. If there's a mate handy, get him to lend a hand, as it's much easier when it's being turned on both sides. Add the rest of the water, mix well again, and sort of chop through it with the shovel--this will show any unmixed parts, or any parts that are too wet.

You might want or need colouring in your mortar or concrete. If so, it's available in powder form. Make sure that you always measure it carefully, so as to avoid changes of colour in the different batches.