Revision as of 09:26, 20 April 2009

There are several ways to mix mortars.

In almost all cases the dry components are mixed first, then water is added and mixed in. There are also times when mixes are used dry.

Cement mixer

Very popular, but too expensive and bulky for small jobs. Storage is often impractical. Its often cost effective to buy one for a job then resell afterwards.

Always rinse out before the cement sets if you want the machine to last well.

Can be used to break soft bricks down into powder/pieces which can be incoporated into mortars. See Pozzolan for information.

Can also be used to break glass into cullet. Add the glass and add a brick. Pick a hard brick rather than a soft one.

Ditto scrap tiles.

Paddle Mixer

Better suited to paints and lime mortar.

When used with haired or fibre reinforced mortar mixes these tend to form 'dead mice' clumps of hair.

Board & Shovel

Mix sand & cement dry on board. Make a ring of the mixture. Add a little water in the middle and fold the dry mix in. Repeat until mixed.

Sandpit

This is a flat board with raised edges. Mix dry materials, then add water and mix in. The advantage over a board is its not necessary to maintain a ring of mixture to prevent water escape, so work can be quicker.

Bucket & Shovel

Don't fill too full, or you won't be able to mix. Half full is comfortable, more soon becomes hard to mix. Some tendency not to mix material at the bottom well, so the bottom of the mix needs extra attention.

Fast Bucket Method

For small amounts its faster to toss the bucket than mix with a small shovel. Move the bucket rapidly in a banana ( shaped motion, and the contents will go round and mix very quickly. At 2 tosses a second a batch can be done in 20 seconds once the water is added. Energetic but very quick.

The bucket needs to be a quarter full or less.

Tarpaulin

Place tarp on the ground, in a shallow hollow depression if available. Mix dry sand & cement, add water, then 2 people lift opposite corners alternately to mix the mortar. Quick.

Rubble bag

Not a good method, but usable when there's really nothing else to hand. A slow way to mix, and prone to pockets of unmixed mortar remaining. Always some risk of holing the bag too.

Mix mostly with a scoop or trowel, avoiding use of sharp, pointed or square cornered tools. To get all the mix incorporated its necessary to at times lie the bag down and lift its base so all the mix drops into a pile further up the bag.

Only practical when the bag is mostly empty, and the mortar mix forms a layer in the bottom of the bag. Mixing is more or less impossible when significant bulk is present in the bag.

Drum

A drum with securely fitting lid can be used as an unpowered cement mixer. Mixing is much easier if you bolt a bar or 2 down the side on the interior, like the paddles in a motorised cement mixer. Turn by hand or roll along the ground to mix.

The drum can be whatever size suits you, so size and cost are typically much less than for a powered mixer. This often makes storage practical.

Mortar Board

Very small amounts can be mixed on a hand held mortar board with a trowel. The same ring technique is used as with a full size board.

Mega mixer

For really large batches it is possible to make a giant mixer driven by a car engine. These can be scaled up versions of a cement mixer for cement mortars, or a giant version of a food processor for Papercrete and similar formulae.

Only suited to large cement mixing jobs, Papercrete and similar mixtures. Making one is not a trivial exercise.

http://www.livinginpaper.com/mixers.htm

Difference between revisions of "Cement mixing"