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Posted: Tue Sep 10, 2013 3:07 pm
by mellie_man
Hi
I want to rip up an area of 5mx5m tarmac and replace it with concrete slab(4", about 2.5m3 i think). I know how to lay sub-base etc, but wanted some advice on the proper way to lay.
I think it will need dividing into 3 or 4 bays (will be getting ready mix), and I wanted to include a linear drain ( into existing rainwater drain. Area has exisiting garden/house walls on three sides, so whats the best way to lay it and include boundary and bay expansion/contraction (12mm flexcell?) joints in one day/pour. (i.e how to tamp down when you only have access to one side).
no mesh reinforcement planned!
Or an I trying to be too clever and should just use 4x1 all round and as bay divider and then remove and fill in gaps (though am DIY to don't have access to hot bitumen and professional joint fillers seem very expensive)? Also want to minimise chance of my dogs scratching it out.
thanks
Posted: Tue Sep 10, 2013 5:30 pm
by GB_Groundworks
wear wellies.......
Posted: Tue Sep 10, 2013 5:43 pm
by TheRockConcreting
Personally for the sake of an extra 2m3 of concrete i would up the slab to 175mm (7") and have a joint less slab, you will need some type of isolation joint around the three walls, the 12mm fibre board you mentioned will be fine, but i would use a 10mm polyfoam and seal the top.
Preset the isolation joint to height, this will give you something to work off.
Use a sheet of damp proof membrane between your sub-base and concrete.
You will need to use steel reinforcement, i would recommend using A193.
I would recommend you order premix C30 with an air entrained additive. When placing the concrete you will need to hire in a bull float and fresno with a broom attachment. When placing your concrete you mentioned tamping as your intended method, this method is the most overly used bad practice in the uk, by tamping the concrete you are forcing the aggregates to the bottom of the concrete (unless you intend on placing 50 slump), this weakens the surface. Just use a straight edge and pull the concrete back to level, then float.
Once the concrete is hard place a thin poly sheet over the concrete for a few days.
Posted: Tue Sep 10, 2013 7:08 pm
by msh paving
As the person is a diy'er, 7in concrete is too much.road forms are normally 150mm,why use a193 mesh?,most people have tamped concrete on bays like that for years with no problems,pulling a straight edge back leave to many holes,
to hire and use a fresno with a brush is beyond a diy person knowing how to use the brush.
fibre board will be fine ,easy to get from merchants
1000 guage polythene under concrete, MSH 
Posted: Tue Sep 10, 2013 8:34 pm
by TheRockConcreting
msh paving wrote:As the person is a diy'er, 7in concrete is too much.road forms are normally 150mm,why use a193 mesh?,most people have tamped concrete on bays like that for years with no problems,pulling a straight edge back leave to many holes,
to hire and use a fresno with a brush is beyond a diy person knowing how to use the brush.
fibre board will be fine ,easy to get from merchants
1000 guage polythene under concrete, MSH
lol
Posted: Tue Sep 10, 2013 9:34 pm
by mellie_man
TheRockConcreting wrote:msh paving wrote:As the person is a diy'er, 7in concrete is too much.road forms are normally 150mm,why use a193 mesh?,most people have tamped concrete on bays like that for years with no problems,pulling a straight edge back leave to many holes,
to hire and use a fresno with a brush is beyond a diy person knowing how to use the brush.
fibre board will be fine ,easy to get from merchants
1000 guage polythene under concrete, MSH
lol
glad I'm a source of amusement.
More silly questions. How does a simple DIYer hold the flexcell in place for dividers without shuttering sitting on other bay.
use short lengths of bar to stake up half height.
Is flexcell strong enough to take weight of tamping/straight edge (I assume not).
Fill one bay, then part fill other side and remove shuttering to let mix run against flexcell.
I've only laid single bay bases with all round shuttering before!!
Posted: Wed Sep 11, 2013 9:08 am
by TheRockConcreting
mellie_man wrote:glad I'm a source of amusement.
You have misinterpreted my quote, i found msh pavings comment totally ridiculous and had to laugh because this is meant to be a forum of quality trades men giving real advice on how to get the job done properly, but it would seem he has slipped though the net as it were.
In my view a normal joe blow DIYer is just as capable as us pro's of doing a small job, with the right guidance anything is possible. We make money from our trades because we can complete a job must faster and get over problems on our own.
Being a DIYer is not about doing a bad job badly, but given the advice of cowboys like msh paving its only going to end badly.
Now to answer your follow up questions, "how to hold the fibre board in place" mark your height on the wall at both ends then ping a chalk line and fix the fibre board to the wall with 25mm nails.
As for how to screed, you will need to invest in a mag float use this to carefully float the edges to height, so you end up with a 500mm pad off the wall now just use your straight edge to screed (not tramp) the guts.
Posted: Wed Sep 11, 2013 9:46 am
by higgness
Being a DIYer is not about doing a bad job badly, but given the advice of cowboys like msh paving its only going to end badly.
I can see this ending badly
Posted: Wed Sep 11, 2013 12:17 pm
by cookiewales
TheRockConcreting wrote:mellie_man wrote:glad I'm a source of amusement.
You have misinterpreted my quote, i found msh pavings comment totally ridiculous and had to laugh because this is meant to be a forum of quality trades men giving real advice on how to get the job done properly, but it would seem he has slipped though the net as it were.
In my view a normal joe blow DIYer is just as capable as us pro's of doing a small job, with the right guidance anything is possible. We make money from our trades because we can complete a job must faster and get over problems on our own.
Being a DIYer is not about doing a bad job badly, but given the advice of cowboys like msh paving its only going to end badly.
Now to answer your follow up questions, "how to hold the fibre board in place" mark your height on the wall at both ends then ping a chalk line and fix the fibre board to the wall with 25mm nails.
As for how to screed, you will need to invest in a mag float use this to carefully float the edges to height, so you end up with a 500mm pad off the wall now just use your straight edge to screed (not tramp) the guts.
your way out of order there rock msh is far from being a cowboy as you are he was just saying it simply to help a diyer not being to tec minded 
ps do your home work he has laid vast amounts of concrete bays .coming from the veg county
Posted: Wed Sep 11, 2013 1:34 pm
by TheRockConcreting
Im sure a lot of you on here are quiet matey with this msh paver, so i don't expect you to see what i'm saying to well. But it comes down to giving the best advice possible, and the advice given by him is that of a cowboy tradesmen.
Like its said many times in the block section of this forum the advice given here is the best advice possible.
Posted: Wed Sep 11, 2013 2:09 pm
by cookiewales
TheRockConcreting wrote:Im sure a lot of you on here are quiet matey with this msh paver, so i don't expect you to see what i'm saying to well. But it comes down to giving the best advice possible, and the advice given by him is that of a cowboy tradesmen.
Like its said many times in the block section of this forum the advice given here is the best advice possible.
so when i have used a poker on slabs i am also a cowboy as this sends down more aggregate than simple tamping would have also worked with floor sealents north wales who do 1000 m2 at a time on bays have seen them tamp and screed back and they are pro,s and you call going out and buying a specialist trowel big bucks good advice .Giles had it in one wellies
Posted: Wed Sep 11, 2013 2:49 pm
by mellie_man
This is one reason why I try and do all my jobs myself (also being time rich and ££ poor).
No one seems to agree what the correct level of work is and BBoards like this often decend in to pros agruing rather than answering the OPs question
TheRockConcreting - 7 inch/mesh seems a bit OTT when there will only be foottraffic. Also doubles the price!! If I could afford it I would get a pro in.
I really do appreciate everyone who takes the time to read and post on my questions and will take the best I can from each.javascript:%20InstaSmilie()
Will make a wooden bull float to fit bays(Don't want perfect smooth finish) from scraps.
Just got to get my back into the job, if it stops raining!
:rock:
Posted: Wed Sep 11, 2013 5:11 pm
by lutonlagerlout
personal attacks are not necessary
both Jay and Mark are right
jay's advice is a high spec finish and the cost would probably outweigh the benefits
marks is what 99% of people in this country require for foot traffic
I always thought the purpose of tamping WAS to push the aggregates down??
for something like your job mellie I would use a volumetric company,get your subbase correct and flexcel/foam all set up before you start
c30 is right or sometimes they call it pavemix
the slump is very important,you definitely do not want it too wet
run 2 screeds down either side then screed/tamp the middle
(I am spartacus :;): )
if you want to get the petrol station look then spend £100 hiring frenos,bullfloats etc
cheers LLL
Posted: Wed Sep 11, 2013 9:44 pm
by GB_Groundworks
I just did a 150mm slab with one layer of a142 mesh for a 29 ton rto unit, (1200 degree furnace that burns the excess gasses out of the factory)
7 inches is way to much for foot traffic,
No need for a 30 quid magnesium hand float ive got 4 but I do 600m3 -1000m3 a year get a £3 plastic trowel or make a wood one out of a bit of 6x1 and an old handle of a door or kitchen cupboard
As said you can nail, screw, no nails or foam adhesive the fibre cell on
Get your concrete in and rough level with back of rake
Get your wellies and gloves and glasses on and get in there two of you better and just gentle tamp it with a straight bit of 3x2
You'll have enough time to get it right, check it with a level on the tamp
Not piss it up with water thinking it'll make it easier it won't.
You can set a crack control joint in if you want, cut a piece of timber or buy some tilt fillet so in profile looking at the end it makes a triangle shape then fix that in the bottom on top of the dpm ^ facing up in the middle of your bay
See the concrete page on here I'm on iPad or I'd copy link
Once it's level work your way out
If you want a finish on it you've got a few options but they all add complexity require skill and experience
Ideally you'd bull float it with a hardwood or magnesium bull float then when it's curing you'd then finish it with a steel float on a pole then you can add your brush finish etc, I've done brushed Crete with a large soft brush before rather than the specialised brushes
You might have to work your way out troweling with wood or plastic float if no magnesium one(no steel at this point) then when it's flat but trowel marks shown leave it a bit let it cure then when it shoes 1-5mm imprint from boot work your way in either gentley or use some boards then trowel your way out of furthest corner till you are done.
Then as said when hands comes away from surface clean, cover it with to complete the cure. We use spay on curing agents but plastic will be fine for you
Here one we did Albert with a power tamp 6mx13m 150 slab
http://youtu.be/sy1FEU0AW0I