Laying Concrete - advice ?

[Kiwi Phil]

I have 35 cubic meters of concrete drives and parking area to put down.<br />I have not concreted for 15+ years. Then we just finished the job off with a brush (broom) finish, after sceeding it of course.<br />In this country they get the surface really smooth.<br />I have bought a hand float and a bull float (on 2.4m handle).<br />I am right up to screeding off with a screed (3.6m aluminium one).<br />Can some one walk me through what I should do and how I should do it with the floats, and when, (as in when really wet on the surface or a little stiff).<br />The last question: When do I use the edging tool to finish the edges.<br />The parking area I have split in to runs, 2.4m wide. I was going to box up, drop in steel on chairs etc and pour. Next day, remove boxing, move it sideways 2.4 and repeat the operation, ensuring I put in an edge on both sides of the join. Of course the steel in each section will not be tied. Is that a problem.<br />I would appreciate any advice.<br />I am not mixing it. Using a mini Truck with 3.4cubic meters. There are 4 of us, so we should be right if we can just work our the finer details of finishing it off nicely.<br />Cheers<br />Phillip

 

[PW2]

Re: Laying Concrete - advice ?

That's a big job!<br /><br />It of course depends on how smooth you want to get it. For a really smooth surface, it's best to use a "jitterbug" to knock down the aggregate a bit from the surface, so that you have just sand and mix to work with. You do this at the time of the screeding process.<br /><br />You will get a slippery surface when it gets wet if you get it really smooth, but then it will be easy to sweep when it is dry.<br /><br />Anyway, use the bull float to get it as smooth as possible--back and forth slowly--The smoother you can get it, the less you have to work with trowels.<br /><br />Use the edging tool when it is stiff enough to maintain the edge. If you are in an area of large temeprature fluctuations, some expansion joints may be a good idea.<br /><br />Pick a day with consistent temperatures, ideally around 21 degrees C.<br /><br />Concrete work isn't too technically difficult, as long as it is properly formed, but it is hard physical work.<br /><br />Good luck!

 

[Mr.Ladyfish]

Re: Laying Concrete - advice ?

Use a jitterbug or conc. vibrator to get the air bubbles out and prevent honeycombing around the edges. Carefully screed the concrete to get it level and remove any bumps or dips. Bullfloat the surface to the desired finish by working the float back & forth. Takes a little practice. The secret is to not overwork the concrete because if you bring too much of the fines up the concrete will begin to chip and flake off after a while. Work it enough to get it smooth but don't overwork it. Edge it then use a hand float or trowel to remove the lip left by the edging tool. If it is real hot make sure you keep the surface wet after the initial set. That will keep the concrete from curing too fast which will cause it to crack. If it's cold cover with plastic to keep the heat of hydration in. I would tie the steel between each section to prevent settlement/separation. Depends on how solid your subgrade is.

 

[oddjob]

Re: Laying Concrete - advice ?

Ditto on PW and Mr.LF ....<br />If you cant get a jitterbug or whirly-bird as we called them, or even a vibrator probe. Tamp the livin daylights out of the surface with the screening board up and down (working it toward you )several times before the final screening. Its more work but it will get you closer to the jitterbug finish. <br />Bull floating is an art. make sure you raise the pole/handle up when pulling and lower when pushing. You may have to shake the pole to start the movement if it is sticky. If you error here is hard to rework without adding a few hand fulls of mix and re-screening that area. <br /><br />It would be a big plus if you had an well-experienced helper with you as time is of the essense(sp).<br /><br />Steel reinforcement. If settling is a problem in the area, drill some holes into the form board and stick a 2' X 3/8" dia. rebar into the form leaving 1 foot on either side. Tie the steel to the mesh and Godzilla wont be able to shift or crack your slab.

 

[Bondo]

Re: Laying Concrete - advice ?

The parking area I have split in to runs, 2.4m wide. I was going to box up, drop in steel on chairs etc and pour. Next day, remove boxing, move it sideways 2.4 and repeat the operation

????????????????<br />Pour it "In Place"........<br />Then pour the other 1/2 Beside it..........<br />It's going to Weigh Over 70 Tons..........

 

[Kiwi Phil]

Re: Laying Concrete - advice ?

Thank you very much for the advice. I will put it in to action this coming week. Will let you know how it went when I am finished.<br />Cheers<br />Phillip

 

[Boomyal]

Re: Laying Concrete - advice ?

Originally posted by Kiwi Phil:<br /> Thank you very much for the advice. I will put it in to action this coming week. Will let you know how it went when I am finished.<br />Cheers<br />Phillip

Good luck Kiwi, concrete scares me just about as much as fiberglassing. <br /><br />Just be sure to soak the ground before ya pour, especially if it is hot out.

 

[Kiwi Phil]

Re: Laying Concrete - advice ?

It is last month of winter, so temp is way down to around 21-25 C, and humidity 35%.<br />Ground is shale rock bed with good old Aussie clay. Need a Drott to level it though.<br />This job ain't scaring me. Contractor wants $14,000, and I hope to do it well under $8,000, so wearing a big smile (at the moment). Am determined it will go well.<br />The top pad is the tricky one. 20m x 7m. Butts against the house, so has to have a good finish, but has to be the 1st area I pour. <br />Bondo: am moving the boxing over.<br />Once this is done, it is all down hill. Total of 70-72 lineal meters of driveway, 3 m wide. So will just back the truck up, pour, and keep moving toward the gate, with a joint every 2.5m. Finish is not so important.<br />Cheers<br />Phillip

 

[Peter J Fraser]

Re: Laying Concrete - advice ?

Hi Phil,<br />I did the driveway at our beach home last year which was 160 sq/m and approx 20 cu/m of readymix (17.5 Mpa) in one slab.<br />Started the job at 06:00 to beat the sun and all the concrete was placed by 07:15. then the waiting started. I had a very good contractor to place the concrete I did all the prep myself.<br />They were off the job and gone by lunch time - finished.<br />2 days later I had the control joints cut in. The slab is 110mm thick over mmost of the area with no steel in it.<br /><br />Looks good<br /><br />Peter

 

[Kiwi Phil]

Re: Laying Concrete - advice ?

Well I got 2 thirds of the job done - no just kidding. <br />I chickened out on doing the job myself when I saw all the different levels needed butting the house. <br />Have to be careful here when joining slabs to buildings. <br />We have Termites all over the place (white ants) and under no circumstances can you let them in to the home. Will eat it to bits. <br />So concrete had to be minimum 70mm below breather holes in bricks. So got in a contractor to do the job. Has got down 29cubic meters so far, and has a 45m long run (3m wide) to finish. Does it on weekends at a good rate, so although i have not saved what I hoped, I am still about 20% savings by buying all materials and paying him labour only. Savings will exceed $3,000, so I am happy.<br />Looks really good too.<br />Cheers<br />Phillip