plasticiser

[briwire]

I'm building a small garden wall, and a while ago, I was asking a brickie for any tips. The main one he said was to use a plasticiser. He reckoned that even he would struggle without it.

I bought a bottle of Febplus from B&Q, for about £2.95. On the back, it gave deatails about how much to use, saying that it is related directly to the amount of cement used, quoting 70-140ml per 25kg of cement.

Bera in mind that I am doing this after 9 hours at work and after my tea, so I only mix a small amount, enough for me to work for an hour or so. I have been mixing about 1.8Kg of cement with 5 portions of the same in building sand.

This works out at around 8ml in the mixing water. However I am struggling to get the mortar to form a buttery consistancy.

Any ideas what i am doing wrong?

 

[roughcaster]

You're not doing anything wrong as such, but to get the benefit from plasticiser, you will really have to mix the mortar hard, and keep turning it over, and beating it, and chopping at it with the shovel, or whatever you're mixing it up with. Plasticiser in the water, plus all the mixing, turning, beating etc, puts millions of microscopic air bubbles into the mix and that is what makes it "buttery". The best mortar is made in a cement mixer where it gets thrown around the drum over and over again, but you can still get a good batch made by hand. Remember though, just adding more water will not make mortar buttery, hard work with a shovel will.............. unless as I said, you have a mixer.

Roughcaster.

 

[^woody^]

How are you mixing this? A hand mix is harder to get smooth. The longer the mixing (in a mixer) the more a poor sand will become workable.

For this purpose your mortar does not need precise guaging, as long as you don't go mad with the plasticiser.

Also what sand are you using? A building sand will go smooth, but a sharper sand will not - however much plasticiser you use.

As a guide, in a 'belle' mixer you would want about 1/2 a tea-cup of Feb-mix per load. For a barrow, you would want about 1/4 of a tea-cup. But really you need to adjust this to suit the sand.

If the sand is poor, (and you cant change the sand) then lime instead of plasticiser would be a better bet

Don't tell anyone I said this, but a teaspoon of Fairy liquid (in a barrow size mix) will probably give better results for your purpose

 

[roy c]

Here is a little tip that I discovered a long time ago, if you are only knocking up a little (or large ) amount of mortar, get your self a piece of viscreen or a small tarpaulin (6ftx 4ft) is fine. Measure your mix out (ie: 4to1) and put it dry on to your viscreen or tarp. Take hold of the two corners and fold the mix over from end to end till it is well mixed. Then make a well in the middle and put some water in and your measured amount of additive,and fold over again from corner to corner adding water (plain water) as the mix starts to fold together. And after a while you will get a perfect mix ready to use with not having to keep turning it over with a shovel!!!! I have made large mixes up like this by just making the viscreen larger and getting my mate to hold one corner and me holding the other. Once you have done this a few times you will find this method brilliant, and if you have ever had trouble with "balling" in the mixer when you are trying to mix "floor mix " or a mix for stone-work then this is the way to make easy perfect mixes every time Tell us how you get on if you use or have heard of this method before....

 

[briwire]

Did a few more tonight and spent longer turning and mixing the mortar. I also added a little more Febplus to the mixing water, although not exceeding the limits. It seemed more workable.

Thanks for the tips.