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Posted: Tue May 14, 2013 8:09 am
by r44flyer
Hello all,
I'm pressing on with our patios but I'm about to run out of sharp sand I'm using to lay them (8:1 mortar). I have a bulk bag of building sand that will finish the job, and is largely waste otherwise. Although not ideal am I going to have problems if I use this instead or will it do?
Thanks
Posted: Tue May 14, 2013 9:55 am
by TheRockConcreting
Building sand has a high clay/silt content, you will end up with a much weaker mix.
Posted: Tue May 14, 2013 7:43 pm
by digerjones
if it was me i would have being putting in a bit of building sand in the mix to use it up, before i ran out of sharp sand.
Posted: Tue May 14, 2013 8:11 pm
by dig dug dan
if it was me i would have being putting in a bit of building sand in the mix to use it up, before i ran out of sharp sand.
Hindsight is a wonderful thing!
Posted: Tue May 14, 2013 8:29 pm
by r44flyer
digerjones wrote:if it was me i would have being putting in a bit of building sand in the mix to use it up, before i ran out of sharp sand.
I have been, 50:50 mix, I just had more building sand to start with.
What IS funny is I thought it was sharp, and when I uncovered it, 6 months after delivery, I find it's not! So instead of two each, I've got 3 and 1, thus one spare building sand I have no use for. Everything I need to do from now on is paving mortar, concrete haunching and block laying course.
If it's a waste of time using it for any of the above, I could always blend it into the lawn prior to turfing I suppose?
Posted: Tue May 14, 2013 9:50 pm
by lutonlagerlout
I have been in a similar spot but even 1 shovel of soft sand in a mix affect the way it feels
a lot of the patios that i see that have failed have been donein building sand and cement
especially a weak 8:1 mix
for the sake of £45 I would buy the proper gear
LLL
Posted: Tue May 14, 2013 11:02 pm
by r44flyer
Fair enough, thanks for the advice.
The 8:1 mix I have used following what I have read on the site, being a 10:1 mix strengthened for being wetter, which, as a diy-er, I did find easier to work with for getting levels etc. Admittedly this wouldn't have assumed 50/50 sharp and soft.
I'm pleased with how hard it's gone off though.
Posted: Wed May 15, 2013 12:29 pm
by Tony McC
A bigger problem when using building sand with pale coloured flags is staining. Many of the building sands have a relatively high clay content, and some have a fair bit of iron mineral too. This can be drawn up overnight from still-plastic mortar through the more porous sandstones (Fossil Bloody Mint in particular!) and be deposited on the surface, leaving a reddy-brown or reddy-orange stain.
Doesn't always happen, but when it does, it can be almost impossible to shift.
Posted: Wed May 15, 2013 7:19 pm
by r44flyer
Thankfully none of that has appeared.
Sharp sand on order for tomorrow, as is the sunshine 