When mixing mortar or concrete is there any reason not to use more
cement than necessary? If I use a standard mix I will end up with
surplus cement which won't keep. If I use more cement, I might be able
to avoid buying one bag of sand. Not a major saving, but there is also
the problem of getting rid of the surplus cement.


--
Michael Chare

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On 26/06/17 15:58, Michael Chare wrote:
When mixing mortar or concrete is there any reason not to use more
cement than necessary? If I use a standard mix I will end up with
surplus cement which won't keep. If I use more cement, I might be able
to avoid buying one bag of sand. Not a major saving, but there is also
the problem of getting rid of the surplus cement.



If you go "stronger" than 3:1 sand/cement, it can start to become less
strong. If you remain weaker than 3:1 usually no problems barring a few
special cases.

On 26/06/2017 15:58, Michael Chare wrote:
When mixing mortar or concrete is there any reason not to use more
cement than necessary? If I use a standard mix I will end up with
surplus cement which won't keep. If I use more cement, I might be able
to avoid buying one bag of sand. Not a major saving, but there is also
the problem of getting rid of the surplus cement.


Since the cement binds the sand gains together I should think that a
serious excess of cement would mean there was cement not in contact with
sand or ballast. That would presumably result in a weaker concrete.

Cement that gets damp sets to form a not very strong substance.

Incidentally the worst thing you can do use too much water. The stiffer
the mix the stronger the concrete.

Bill

Bill Wright explained on 26/06/2017 :
Incidentally the worst thing you can do use too much water. The stiffer the
mix the stronger the concrete.

Bill

Which is why engineers do a slump test on newly delivered ready mix,
before accepting it.

On Monday, 26 June 2017 15:58:40 UTC+1, Michael Chare wrote:
When mixing mortar or concrete is there any reason not to use more
cement than necessary? If I use a standard mix I will end up with
surplus cement which won't keep. If I use more cement, I might be able
to avoid buying one bag of sand. Not a major saving, but there is also
the problem of getting rid of the surplus cement.

The only reason not to is cost, until you reach somewhere around 3:1. Going richer than 2:1 or 3:1 reduces strength.


NT

Michael Chare wrote:
When mixing mortar or concrete is there any reason not to use more
cement than necessary? If I use a standard mix I will end up with
surplus cement which won't keep. If I use more cement, I might be able
to avoid buying one bag of sand. Not a major saving, but there is also
the problem of getting rid of the surplus cement.

Three years ago I used a small part of a bag of cement to point between the
drive and the walls of my house.
I stuffed a black plastic bin liner in to the bag of cement and stored it in
the garage on top of a bin liner.
A couple of weeks ago a small part of the pointing fell out when I jet
washed the drive............... like this sort of pointing tends to do.
The cement in the bag was still powder, no lumps and when mixed with
sand/water cured very well.
Food for thought?

"Michael Chare" wrote in message
news
When mixing mortar or concrete is there any reason not to use more cement than
necessary? If I use a standard mix I will end up with surplus cement which won't keep.
If I use more cement, I might be able to avoid buying one bag of sand. Not a major
saving, but there is also the problem of getting rid of the surplus cement.


As has been pointed out, a standard mix isn't called a standard
mix for nothing.

As you say cement won't keep whereas sand will. One way to avoid
waste in individual jobs which won't take a whole bag, is to have a job
or jobs on the side that can use up any surplus mix but don't necessarily
need to be finished off in the one go. Having the small job(s) which
need to be finished off at some point can also act as an incentive to
get started on the next big job.


michael adams

....

On 26/06/2017 16:58, Harry Bloomfield wrote:
Bill Wright explained on 26/06/2017 :
Incidentally the worst thing you can do use too much water. The
stiffer the mix the stronger the concrete.

Bill

Which is why engineers do a slump test on newly delivered ready mix,
before accepting it.

I have found it surprising how much difference only a little extra water
makes.

--
Michael Chare

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"Harry Bloomfield" wrote in message
news
Bill Wright explained on 26/06/2017 :
Incidentally the worst thing you can do use too much water. The stiffer
the mix the stronger the concrete.

Bill

Which is why engineers do a slump test on newly delivered ready mix,
before accepting it.

I used to do that when I was a chain boy.....and make cubes ........

On 26/06/2017 16:58, Harry Bloomfield wrote:
Bill Wright explained on 26/06/2017 :
Incidentally the worst thing you can do use too much water. The
stiffer the mix the stronger the concrete.

Bill

Which is why engineers do a slump test on newly delivered ready mix,
before accepting it.

Not just engineers. Readymix customers. Me.

Bill

On 26/06/2017 16:32, Bill Wright wrote:
On 26/06/2017 15:58, Michael Chare wrote:
When mixing mortar or concrete is there any reason not to use more
cement than necessary? If I use a standard mix I will end up with
surplus cement which won't keep. If I use more cement, I might be able
to avoid buying one bag of sand. Not a major saving, but there is also
the problem of getting rid of the surplus cement.


Since the cement binds the sand gains together I should think that a
serious excess of cement would mean there was cement not in contact with
sand or ballast. That would presumably result in a weaker concrete.

Cement that gets damp sets to form a not very strong substance.

Incidentally the worst thing you can do use too much water. The stiffer
the mix the stronger the concrete.

Bill

However once it is past initial set (Green) the more water it gets the
sooner it will attain maximum strength ... it is not as many think by
drying.

On 26/06/2017 15:58, Michael Chare wrote:
When mixing mortar or concrete is there any reason not to use more
cement than necessary? If I use a standard mix I will end up with
surplus cement which won't keep. If I use more cement, I might be able
to avoid buying one bag of sand. Not a major saving, but there is also
the problem of getting rid of the surplus cement.


I would not use over rich mix .... these mixes have been tested and
confirmed over years ........ too much cement will end up with brittle
concrete.

With mortar it is also designed to force a crack on mortar line in the
event of stress not the brick or block.