Mixing mortar and concrete - what am I doing wrong?

[diyreg]

I've mixed mortar using 1 part cement to 5 parts sand. It sets and dries to a green colour, not the sort of sandy colour on houses

I've mimxed concrete with 1 part cement, 3 parts sand, 5 parts aggregate and I end up with a similar looking colour to my mortar, not the sort of grey cement usually is.

What am I doing wrong?

 

[Deluks]

Assuming it's in date, not a problem. It will dry greyish.

 

[stuart45]

The traditional mixes for concrete were 1/3/6 or 1/2/4 cement/sand/gravel. Nowadays all in ballast is the norm. The theory is that half the volume of sand fills the gaps in the gravel so 1/3/6 is about 1/6 and 1/2/4 is 1/4 cement/all in.
You have got a bit too much sand in the concrete mix. Also you need to use the correct type of sand, not building sand.

 

[Nige F]

Cats have ****ed in the sand

 

[hotrod]

Might seem like a daft suggestion but you are using clean water aren't you?

 

[rambling]

The Brand of cement and type colour of sand makes a huge difference, if you are building you should get this right first, I have found that Blue circle cement alters the colour (dull's it) of the final mortar a lot more than, say, Castle cement for instance.

choose the colour sand closest to the mortar shade you have, and then try a different cement than you are at present, generally the sand should be darker than the mortar colour you wish to end up with. Make sure you are using the right sand, sand for mortar (soft) not sand for render (sharp). if necessary take a spoon and some plastic containers to the builders merchant and sample their sands for colour comparison.

Small measured quantities of white cement can substitute some of the regular measure of cement, useful if you want the mix to look the same when indoors for exposed brick or stone work, as indoor light can dull the appearance of mortar.

Mix small quantities and try them out on a spare brick in the same light conditions to get your match, bucket handle finish appears lighter than trowel edge scraped finish, which will make the same mix look a different colour (darker) when dry. I hope this helps you.

 

[diyreg]

Thanks folks - I've been using building sand for the concrete and mortar. Didn't realise I needed to use sharp sand for teh cocnrete, but I do now.

Cheers

 

[rambling]

Cement is a lime based product supplied in paper bags used to make Motar, Render, and concrete. all different things
Just so we are clear.

Mix soft (or general builders ) sand with cement to make mortar.

Mix sharp sand with cement to make surface render and floor screed

mix (3/4 to dust pre mix for concrete ) aggregates to cement to make concrete floors footings drives and paths etc. If you need more trowelling "fat" add more sand and cement.

Different Quarries quarry different colour sands, you can always contact a quarry direct to obtain your sand by the lorry load much cheaper way to buy it if you have a big job and some place to tip it .

Cement additives are also used widely depending on the task,

Plasticiser for mortar. Aids with handling abilities.
PVA adhesive for wall prep and additive to render mix.

 

[wavetrain]

Cement is a lime based product

Cement is not a lime based product!

Cement is produced by heating crushed chalk and clay. Lime (calcium hydroxide) is not a component of cement or produced when cement is made. Plenty of info on the Portland cement process on the Internet for you to read.

 

[rambling]

I stand by what I said.

 

[merlin50]

The components to make cement are limestone, silica, aluminum and iron. Silica is usually sourced from sand. Aluminum is found in clays and fly-ash from power plants. Iron can come from several sources, including iron ore or waste streams from other process that are high in iron, such as mill scale. These components are mixed together in ratios with strict tolerances to be able to make the chemical reaction possible to make cement.

 

[mointainwalker]

re the above

Whilst it may be true ( don't know) that lime is involved in the manufacture of cement, I feel it is absolutely wrong to introduce this into normal discussion.

Cement and lime are completely different as finished products and - unless for a chemist or geologist - it is useless and possibly confusing for the end-user to be alerted to these facts.

Feel "Rambling" is completely wrong in his way of saying things.

 

[stuart45]

Rambling is a lady. The giveaway is her advice to take a spoon to the merchant

 

[Nige F]

I stand by what I said.

but you also said it`s in paper bags - it`s in plastic and I bet you thought it was still made @ Lewes - It`s not Nor anywhere else in this poxy little island

 

[wavetrain]

Ramblings post reads like a copy and paste from an unknown source. It is cerainly rambling.

Here is the link for OPC http://en.wikipedia.org/wiki/Portland_cement

I wonder if Rambling thinks limestone is lime? It is not.

To confuse matters further, 'lime' can refer to 'Quick Lime' - Calcuim Oxide, or can refer to 'Slaked Lime' - Calcuim Hydroxide.

In the old days lime morta was prepared by dumping large lumps of quick lime (fresh from the lime kiln) into water filled ponds dug at construction sites and allowed to bubble away and be slaked to slaked lime over a period of weeks. The lime putty thus created was mixed with sand, hair etc to make the lime morta.