• Looking for a smarter way to manage your heating this winter? We’ve been testing the new Aqara Radiator Thermostat W600 to see how quiet, accurate and easy it is to use around the home. Click here read our review.

why was my concrete "rocky"?

If you go to a decent builders merchants, you should be able to buy 10mm limestone in 25 kg bags, also grit sand in the same size, plus a bag of cement. you can then make your own, which will be much better for your job. Don't forget the feb mix.
 
catlad said:
If you go to a decent builders merchants, you should be able to buy 10mm limestone in 25 kg bags, also grit sand in the same size, plus a bag of cement. you can then make your own, which will be much better for your job. Don't forget the feb mix.
Click to expand...
thank you for the help.
using my search engine i have been trying to figure out what exactly makes up febmix, but there seems to be some questionable elements used for "air entraining", which tend to go undisclosed from what i can tell. i think i will skip it to be honest, just to be safe, as i am not looking for perfection, just function. i am using concrete because it is a safe material for foods (once i have leached it to bring the pH down) and i don't want to risk putting unknown chemicals in there.
thank you for the help all the same! <3
what difference does it really make? is it a huge difference?
 
It's always better to mix your own blend for 'fine' work. In your case you need builders sand, 10mm gravel (pea gravel) and cement.
Mixing ratio of 1 measure Cement, 2 measures of Sand & 3 measures of Gravel. Febmix makes the mix more workable - a benefit when working with moulds. Add water slowly to make the mix workable.
Mate and I use a mixing bath to hand mix in - an old baby bath will work If you have one. Old days I would use a big (4' sq) piece of board to mix on.
If you can work out a means of vibrating the mould as you fill so much to the good.
 
Last edited:
Diver Fred said:
It's always better to mix your own blend for 'fine' work. In your case you need builders sand, 10mm gravel (pea gravel) and cement. Mixing ratio of 1 measure Cement, 2 measures of Sand & 3 measures of Gravel. Febmix makes the mix more workable - a benefit when working with moulds. Add water slowly to make the mix workable. If you can work out a means of vibrating the mould as you fill so much to the good.
Click to expand...
thank you for the reply
i will start sourcing the components as soon as i can. fingers crossed it comes out usable anyway :)
 
Standard plasticizer is mainly an air entraining agent. When mixed up properly, it keeps thousands of tiny air bubbles in the mix which act as mini ball bearings and make it workable with the minimum amount of water. Without it you need more water which weakens the mix. It's especially important with bricklaying mortar, but can also be useful in concrete for certain jobs.
 
Thinking all the way back to my earlyish years, the ideal concrete mix for general building usage was to the ratio 3/4" 4-2-1 OP 2"slump; where the 4parts was the 3/4"agregate (downgraded), the 2 was the fines (blended sand) and the Op was ordinary Portland cement mixed with water to give a 2" slump when tested before pouring. That mix was SO popular, it was used as the 'control mix' by the then Ready Mixed Concrete company.

For container making, I'd opt for 3/8" 4-2-1 OP and less slump at say around 1" to 1&1/2" well rammed home and then vibrated to ensure zero air bubbles. .(y)
 
Scally-Ho said:
Thinking all the way back to my earlyish years, the ideal concrete mix for general building usage was to the ratio 3/4" 4-2-1 OP 2"slump; where the 4parts was the 3/4"agregate (downgraded), the 2 was the fines (blended sand) and the Op was ordinary Portland cement mixed with water to give a 2" slump when tested before pouring. That mix was SO popular, it was used as the 'control mix' by the then Ready Mixed Concrete company.

For container making, I'd opt for 3/8" 4-2-1 OP and less slump at say around 1" to 1&1/2" well rammed home and then vibrated to ensure zero air bubbles. .(y)
Click to expand...
thank you.
i did read about slump during my research. i haven't got a cone (calling it that because i forgot what it's called :) ) but maybe i will invest in one if i am going to be building more of these. i do plan to build probably 10 of them, maybe more.
thanks for the help
 
You don't need a slump cone for heaven's sake!! Just make the concrete as stiff as you can sensibly use it because that will give you the best finished concrete. No Clerk of Works is going to come along and condemn your mix as being out of spec!

I wouldn't bother with a` plasticiser either and just to clarify Air Entraining is commobly specified for roadside or marine concrete structure where the micro bubbles are intended to act as crack arresters within the matrix, Yes there is workability benefit but the strength potentially REDUCES zs 5% (typically) isn't concrete so the admix is combined with a plasticiser to enable the water-cement ratio to be reduced to Increase the strength.
 
SpiderTrev said:
thank you.
i did read about slump during my research. i haven't got a cone (calling it that because i forgot what it's called :) ) but maybe i will invest in one if i am going to be building more of these. i do plan to build probably 10 of them, maybe more.
thanks for the help
Click to expand...
You are making some planters not building a reinforced multi storey car park (last time I performed a slump test) , forget plasticiser unless you are going to start laying bricks , just careful methodical tamping of a well mixed workable but not to sloppy batch as you fill the mould using a steel/wood rod will give you the desired result, if not, then go for some plasticiser and a vibrating poker and a slump cone and take cube samples to send off for compression testing and don't forget to make sure the air temp is above 4 degrees and not dropping otherwise you are into heating and mould protection
 
Last edited:
stevie888 said:
You don't need a slump cone for heaven's sake!! Just make the concrete as stiff as you can sensibly use it because that will give you the best finished concrete. No Clerk of Works is going to come along and condemn your mix as being out of spec!

I wouldn't bother with a` plasticiser either and just to clarify Air Entraining is commobly specified for roadside or marine concrete structure where the micro bubbles are intended to act as crack arresters within the matrix, Yes there is workability benefit but the strength potentially REDUCES zs 5% (typically) isn't concrete so the admix is combined with a plasticiser to enable the water-cement ratio to be reduced to Increase the strength.
Click to expand...

Dereekoo said:
You are making some planters not building a reinforced multi storey car park (last time I performed a slump test) , forget plasticiser unless you are going to start laying bricks , just careful methodical tamping of a well mixed workable but not to sloppy batch as you fill the mould using a steel/wood rod will give you the desired result, if not, then go for some plasticiser and a vibrating poker and a slump cone and take cube samples to send off for compression testing and don't forget to make sure the air temp is above 4 degrees and not dropping otherwise you are into heating and mould protection
Click to expand...
thank you both. it did feel like i was starting to over think things haha i will keep it simple. thanks
thanks for the note about the temperature too! it is getting colder, i better work fast
 

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
You must log in or register to reply here.

Similar threads

A
Postcrete vs concrete
2
Replies
23
Views
15K
Captain Nemesis
C
R
Concrete Mix Help Please
Replies
13
Views
2K
noseall
noseall
S
Some questions about concrete (i'm confused)
Replies
6
Views
57K
hammerswinger
hammerswinger
M
How much water to concrete mix
Replies
4
Views
3K
Diver Fred
D
festive
postcrete v rapid cement n ballast
Replies
3
Views
8K
festive
festive
Back
Top