Sand:Cement:Lime mix

I am trying to mix the right quantities of sand, cement and lime to produce a 5:1:1 mix. I have 25kg bags of cement and lime. The lime (hydrated) bags are slightly bigger than the cement bags and I am having difficulties getting the right quantities to mix. Using a half bag of cement is approx 3-4 shovel loads and using a half bag of lime I get approx 4-5 shovels but I expect will be lighter than the cement since it is denser. Ideally I would like to do this by the half bag to make the mix accurate. How many shovels of the sand should I be using? Someone recommended 10 shovels to 1/2 bag of cement & 1/2 bag of lime but in volume (i.e. not weight) this doesn't seem right to get a 5:1:1 mix. Incidently I'm using a 100ltr electric mixer to mix it all up. Thanks Paul

Reply to
paul
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AFAIK quantities for mixing mortar have traditionally always been by volume. While the actual ratio is probably not critical shovelfulls are a pretty inaccurate way of measuring volume. FWIW I usually use 3 gallon black plastic work buckets as a way of measuring volumes both for mortar and concrete.

Reply to
Roger

1:1:6 by volume is the standard mix. The other well known non-equal lime:cement mixes fail prematurely. To convert to weight ratios I guess you'd just need to measure the densities and work it out.

I'm wondering what youre using 1:1:5 for though, its not a mix I know of any application for.

NT

Reply to
meow2222

When making cement & lime mortar its used dry.

NT

Reply to
meow2222

Yep by volume, the real question is do you measure the lime before or after you've puttied it? I assume before since how do you account for a varying water content?

-- Mike W

Reply to
VisionSet

You dont need to putty the lime for a mortar of this ratio. The lime is just being used as a plasticiser and all the setting is done by the cement, so the amount of lime is not critical

Anna ~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repair and conservation / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____|

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Reply to
Anna Kettle

The mix I'm using is for a Bulwell stone wall which is also a retaining wall, i.e has earth behind it all the way to the top of the wall which is approx 2.5m high. It was recommended by a builder I had round, having said that the next guy I had round recommended a lime:sharp sand mix without cement. Paul

Reply to
paul

This is a soft stone, a limestone, so should be done in lime mortar rather than cement. Cement will work, but when it finally comes apart it pulls the edges and corners off the stone with it, which does not look good. Lime also has the advantage of being able to accomodate limited movement, unlike cement.

The standard lime mortar is 3:1, this is 3 parts sand to one lime putty. The putty is made by mixing bagged hydrated lime with water to make a paste, and storing it airtight for a few weeks. Cement and lime mortar is not lime mortar, or anything like it.

I know someone who uses bagged hydrated lime, mixes with sand, adds water and uses it without storing first, and says he gets good results. Ive not tried that.

The downside of lime is its slow setting. You dont want to build 8' in a day, must let the bottom section set first. Also, just like cement, dont use a bag of lime thats sat around forever. Cement wont mix in the first place, old lime will, but it wont set. IOW if your lime is old, test a bit sets ok before use. Unsetting lime is a rare problem.

Finally with lime you can make it more decorative by adding crushed black stone or coal to the mix, white with black flecks.

NT

Reply to
meow2222

results.

Reply to
Andrew Mawson

This is training mix. It behaves like mortar and even appears to set as it dries out. However, it doesn't really set and is ground down and rewetted for reuse. If you left it long enough, the lime would actually set (turn to chalk), but not noticably in a week or so that training projects exist before being demolished.

Reply to
Andrew Gabriel

I used a mix in my wall varying from about 1:1:5 cement/lime/sand to

1:1:8 when I got a bit low on sand and cement to 3:1:15 when I nearly ran out of cement.

The more cement the harder and the faster it sets. The more sand the more porous and crumbly it is when it sets.

But really, none of it is THAT critical. What is more critical is tying the whole thing together when you use any cement, to make sure it doesn't crack.

Reply to
The Natural Philosopher

The lime:cement ratio is important. At most ratios, they interfere with each other and result in much reduced strength. However, the 1:1 ratio happens to be good. There's a BRE report on this.

Reply to
Andrew Gabriel

The other issue is premature failure. Lime:cement mixes of other than

1:1 commonly fail prematurely.

NT

Reply to
meow2222

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