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Posted: Sun Apr 13, 2014 11:03 pm
by KAMIKAZEE DIY
Going to remove breeze block wall in back garden and replace with slightly higher fence next weekend. I have aggregates left over from front garden (still not finished) and reckon it would be cheaper to try make my own "postcrete" rather than paying top dollar for it.
Only got weekend to do it, that's why I need concrete to set quick.
I got some "CEMENTONE ACCELARATOR AND PLUGGER", label says 1/2litre accelarator to 25kg cement.
If u get 5 shovels per bag cement this would be 100ml per shovel????
With an ideal water/cement ratio of 1/2litre water per 1KG CEMENT????does this equate to:
1 shovel cement (5kg)
2.5litre gauging water plus 100ml accelarator
4 shovels of gravel
2 shovels sharp sand.
Would this be similar to postcrete? I know it sets quick, used it putting in washing line.
Any improvements to recipe would be appreciated.
Also how long could you expect to have before concrete sets?
Thanks
Posted: Sun Apr 13, 2014 11:21 pm
by lutonlagerlout
postcrete is 4-5 quid a bag your mix sounds ok in theory but why scrimp on something so important?
the old way is just knock up concrete but you need to brace the fence
LLL
Posted: Tue Apr 15, 2014 3:30 pm
by Bob_A
I'm only guessing but I reckon they use ingredients in postcrete that are not normally available.
Possibly quick drying cement that has been tinkered with so that it's really quick and a small amount of some sort of foaming agent
As for you mix if you got the ingredients already then I'd give it a go in one hole and see what happens
If you haven't got the stuff then don't bother, look around and see if the DIY shops are doing an offer on postcrete, especially over the easter weekend.
Posted: Tue Apr 15, 2014 3:54 pm
by dig dug dan
postcrete is made with bone dry materials and its accelaration is down to chemicals which are activated by water.
You can make your own, but be prepared to clean everything IMMEDIATELY after each mix. If you use a cement mixer, wave bye bye to the drum it will get cemented up instantly.
Personally, i have recently gone back to ballast and cement, and i tend to do a runny strong mix, pour it in the hole and poke it round with a batten. Its cheaper, and strong. Its only if you need it to instantly cure that i use post fix
Edited By dig dug dan on 1397573726
Posted: Tue Apr 15, 2014 3:55 pm
by KAMIKAZEE DIY
I've got everything I need already. So only spent £6 on accelarator, will do first post and see how it goes. It will be cheaper than postcrete or using the rapid set cement I've seen at b&q.
Nothing ventured, nothing gained........
Cherers
Posted: Tue Apr 15, 2014 3:58 pm
by seanandruby
Seems like another added expense to me this accelerant. Old method all the way with me. As LLL says make sure the post is braced.
Posted: Tue Apr 15, 2014 4:01 pm
by KAMIKAZEE DIY
Thanks for the help guys. Getting mixer on hire, will do one post hole and rinse mixer and assess the situation. £150 deposit on mixer - I want it back!!!!
Thanks again for all your help.
Cheers
Posted: Tue Apr 15, 2014 5:26 pm
by lutonlagerlout
last 3 fencers i have seen in action were using postcrete
the cost of the posts,panels and gravel boards are that high that £4 for postcrete is negligible
LLL
Posted: Wed Apr 16, 2014 8:58 pm
by Bob_A
dig dug dan wrote:postcrete is made with bone dry materials and its accelaration is down to chemicals which are activated by water.
Any ideas of what the dry chemicals might be. I've only ever seen fluid accelerators.
Posted: Wed Apr 16, 2014 9:59 pm
by digerjones
when i have done concrete post and panels i use sharp sand and cement. mix it dry in barrow, pun it round post, no need to prop. end of day pour water round post or pour repid setting agent. done it like this for years and never had any come backs.
Posted: Wed Apr 16, 2014 11:34 pm
by Brucieboy
Bob_A wrote:dig dug dan wrote:postcrete is made with bone dry materials and its accelaration is down to chemicals which are activated by water.
Any ideas of what the dry chemicals might be. I've only ever seen fluid accelerators.
The main accelerator in post-mix and other similar named products is another type of cement - either calcium aluminate or calcium sulfoaluminate. It's blended with conventional Portland cement to give the rapid set needed. These products are laboratory engineered through extensive testing to determine optimum proportions - hence the slightly higher price. Get the blend wrong, and they can set in seconds or be no different to Portland cement.
Posted: Sun Apr 20, 2014 9:37 pm
by rxbren
bit late to the thread but i found the liquid accelerators to not be very good especially at a dose of 100ml per mix if i remember correctly a full 5 litre tub is good for treating around 100kg of cement even mixing in 300ml does not set much faster than ordinary protland
rapid set cement is better but at around £11 a bag is costly so unless you have a lot of posts to put in your better off with premixed postmix/crete