How Do I Mix Concrete By Hand ?

[scooterboy]

Hi!

Got an area of the garden that I want to turn into a sort of patio (terrace). Ain't a large area, roughly 4 by 5 metres (12 by 15 foot). Reckon I'll have to use concrete, but know absolutely nothing about mixing concrete up. The GF insists I do the job myself - she just hates to see me relaxing, heh, heh! The patio wouldn't be supporting heavy stuff, just some tables and chairs, flower pots (lots of 'em) and other things. Maybe also a roof, if that makes a difference.

The said area is pretty level - I'm aware that I'll have to level it off where it's needed.

Oh, the garden soil is sandy - it's definitely not "earth". Don't want tiling done or

anything fancy - just the bare concrete. Don't have (or want to have!) concrete mixers or other machinery - the job has to be done using the bare essentials.

Question is, how the hel_l do I mix concrete (by hand) and how thick does the layer

need to be? Does the whole area have to be concreted at the same time, or can part of it be done - and the rest later ? What is actually the difference between concrete and cement? A step-by-step guide would be great!

Any hints (polite ones, preferably!) ? Thanks!

[paulsmithson]

One cement: 2 sand : 4 stone. Mix and add water---too much water means weak concrete!

lay it 100mm thick over a bed of levelled sand preferabley with some reinforcing mesh 25mm from the bottom. lay it in bays if the area is too large for you to cope with in one mix

form construction joints wherever you stop work til the next day.

Lay to wood formers and tamp lightly and drag the tamp rail to get it level.

brush finish the surface to make it non slip and hide any markings etc ( especially if you are inexperienced at this)

finally cover it with damp hessian to help stop it drying out too quickly then wet the hessiaqn again.

Good luck

[pap]

browse the internet.

Are you buying concrete bags? Renting a tray that you tow into place and dump or are you mixing sand, cement and gravel to make your concrete?

4 by 5 meters is a lot and I mean a lot of mixing.

Most unreinforced concrete(depending on quality) needs to be 4-6inches thick. If your going to build on it later go with 6 inches.

If you are putting posts on it for a patio or to build on in the future try to determine where your posts might go and reinforce those areas.

To mix bags of concrete use a wheel barrel and shovel or hoe. Add water until you have the cosistency you want. Should be like pancake batter in consitency. Too much water just add more concrete.

[sfokevin]

Given you size 12x15 make sure you embed a grid of steel reinforcement or rebar into it otherwise you will get cracking - you may want to score in a grid into the surface too which any cracking will follow... here is a nice website: http://www.extremehowto.com/xh/article.asp?article_id=60266

[qualtrough]

Given you size 12x15 make sure you embed a grid of steel reinforcement or rebar into it otherwise you will get cracking - you may want to score in a grid into the surface too which any cracking will follow... here is a nice website: http://www.extremehowto.com/xh/article.asp?article_id=60266

Whenever I have workmen do any cement work here they form a pile of sand and scoop a hole out in the middle. They then pour water and cement in the hole and begin mixing, scooping in sand, cement, and water as needed until the proportions are right. Crude, but has worked well on all our projects.

With labor so cheap here, why are you doing this? I think you are better off finding someone with the experience to prepare the bed and mix the cement property, etc. A lot of work in the hot sun!

[scooterboy]

Hi paulsmithson!

Can you explain what "stone" is? Maybe it's gravel (?) But the mixing ratios are nice to know - thanks.

Hi others!

Was hoping to avoid having to use reinforcing mesh - is this a MUST ?

Buying (or will be) BAGS of concrete.

"rebar" - what is THAT? Scuse my ignorance.......

Otherwise, great hints - thanks, you guys.

[skipvice]

Hi paulsmithson!

Can you explain what "stone" is? Maybe it's gravel (?) But the mixing ratios are nice to know - thanks.

Hi others!

Was hoping to avoid having to use reinforcing mesh - is this a MUST ?

Buying (or will be) BAGS of concrete.

"rebar" - what is THAT? Scuse my ignorance.......

Otherwise, great hints - thanks, you guys.

you did not get enough help from udonmaps

[tutsiwarrior]

drive around locally and find a construction site and watch what they do...you can see concrete activity when you see a pile of sand and of gravel (aggregate) in front of the site...

it's cheap to get local workmen that know what they're doing to do the job...if yer girlfriend reckons that you are a lazybones ask her to help you with the concrete and see what she says...

[kasi]

Given the size you are talking about you will need about 2.3 cubic yards of concrete. That's a lot of mixing. Mixing concrete isn't a lot of fun IMHO! And it's difficult to achieve professional result mixing it in the above mentioned way.

You are going to need forms and wire mesh.

I would recommend talking to the local premixing company and see if you can arrange for a partial load from one of their trucks.

Here's how to calculate the volume of concrete you need

Another option is to rent (or buy and resell a small mixer)

Clean sand and gravel are essential ingredients.

[simon43]

How do you mix concrete?

You don't, unless you have a WP that authorises you to mix it!

Simon

[pap]

Hi paulsmithson!

Can you explain what "stone" is? Maybe it's gravel (?) But the mixing ratios are nice to know - thanks.

Hi others!

Was hoping to avoid having to use reinforcing mesh - is this a MUST ?

Buying (or will be) BAGS of concrete.

"rebar" - what is THAT? Scuse my ignorance.......

Otherwise, great hints - thanks, you guys.

Rebar is steel in the shape of a long 1/2 in pole. Or what ever size you need depending on the project. For your use, probably wire mess is best. Even several layers of chicken wire can work but is not optimal. This prevents the concrete from cracking.

If you are buying bags of cement you need the sand and gravel. If you are buying concrete it already has the cement, sand and gravel mixed together.

With that big of an area you need stress lines. I believe the link one of the other guys put on will have that.

If money is an issue than buy concrete and then mix the concrete in a hole. I not killing yourself is more important hire someone. Construction workers are paid very little in Thailand. If you want something in between order a truck with the required amount and have them bring it to you mixed. I have found that if you factor in your time the cheapest option is to pay someone on something like this.

[The Skipper]

Mixing concrete is the one thing Thais excell at.

Hire them.

Then hire them again to rip it out since the drainage is all wrong, do again and again untill correct.

[tutsiwarrior]

another thing...messin' with rebar before you pour the concrete is a special skill requiring special tools...personally, I'd back off an' get sumone that knows what he's doin' to do the job...

[pap]

Mixing concrete is the one thing Thais excell at.

Hire them.

Then hire them again to rip it out since the drainage is all wrong, do again and again untill correct.

[PhilHarries]

As others have advised, hire someone experienced to do the job. I have concreted an area similar in size to your one and can confirm it aint an enjoyable task (and that was in the UK in autumn with a mixer). Poorly mixed and laid concrete looks <deleted>, is <deleted> and in a short time starts to break up and thus goes to <deleted>.

You need to set your formwork (shuttering) up allowing for around a 1% slope away from the house.

You need to set up the reinforcing mesh, yes it is essential unless tou want the slab to crack, clear of the ground.

You say there is a probability of adding a roof. The support posts for this are best concreted in thus you need to excavate foundation holes and set the posts up before pouring the concrete.

Then you need to mix all that concrete BY HAND in 30 degrees heat. You'll not do it in one pour so you will have construction joints running across the slab which, if not done properly, will form cracks.

No! If you (i.e. your gf) insist on DIY read up about it, go watch others do it then do the first three steps above and buy in premixed concrete.

No! Forget the last bit. Buy a case of beer and install in the fridge. Hire a gang of locals to do the job. Sit back under some shade, supervise the work and enjoy a cool beer or two (you may wish to share a couple with the guys, that always boosts moral).

[jayenram]

No! Forget the last bit. Buy a case of beer and install in the fridge. Hire a gang of locals to do the job. Sit back under some shade, supervise the work and enjoy a cool beer or two (you may wish to share a couple with the guys, that always boosts moral).

Excellent advice!

IMO the rebar should be 9mm diameter steel bar mesh at 200 mm centres in 100 mm thick concrete. Prepare the area using sand/gravel as a base. Raise the rebar using 25mm bricks as support. When the whole area is ready, get the truck mixer in. 2 m3.

[chownah]

Scooterboy,

After everyone trying to talk you out of doing it yourself do you still want to do it? If so please say so and I will talk you through the process of mixing concrete by hand. Please be aware of the fact that you have not only asked how to mix it by hand but you have also asked how to design and build a slab and also whatever is necessary for a roof. It is probably best to start with just learning how to mix the concrete....you could practice by making some garden stepping stones which would give you an idea about how much work it is and also if you make a mistake that is too bad it won't bother you so much to just scrap a stepping stone and try again.

Anyway if you still want to learn how to mix concrete by hand just give a holler.

Chownah

[phibunmike]

Chownah's advice is excellent - do a small project first to learn how to mix it, how quickly it dries off as you work, how tired you get, etc.

I built a brick bbq in my garden and hand-mixed myself as it was a small job (and locals didn't know what I was building). I used a minute amount of mortar compared to your project, but it was VERY tiring. Also, I found that it dries VERY quickly here - you could easily come unstuck on a concrete slab (you want two or three people at a minimum for that).

Good luck,

Mike

Edit> I forgot to say, like the others, "don't do it yourself - get help".

Edited January 19, 2007 by phibunmike

[paulsmithson]

Some excellent advice here.jayenram have you seen some of the photographs here showing concrete being poured into a reinforced slab with the reinforcement resting directly on the prepared sand base!

Might as well not bother eh?

Labour is cheap Scooter and if you have never concreted before you will most likely make a hash of it and then have to break it all out and do it again!

Like Chownah says if you do decide to go ahead pm either of us for more advice.

Personally I would advise against this especially if you are no longer young (?) and are not used to hard-VERY HARD--physical work in a hot climate. on a lighter note I would think that a case of singha should be bought with every bag of cement---you will need it!

[excaliber]

Excellent advice and tips although I failed to see in any of them, "a footing" around the perimeter of the slab for support. Without the footing the slab could easily break away from the house or adjacent structure. A common site in Thailand. (pictures on request)

The footing should be about 12" wide / 30cm and approx. 12" deep.

"Cement" is a grey or white powder that has very little to no strenth without adding aggregates (sand, gravel, rock) which, after mixed with water becomes "Concrete".

The cement to aggregate ratio given is appropriate. In the west we have type II portland cement which is waterproof and unfortunately isn't available here. There the ratio is 3 to 1; 3 aggregate: 1 cement.

You may want to put some color to the slab instead of the usual, unsightly grey.

Several colors are available; red, green, etc. You could spend more money and mix the entire load with color or: after pouring and semi-finishing the entire slab, sprinkle the powdered color on top of the slab working it into the first 1/8" or so using small pieces of plywood (.50m x .50m) to support yourself on top of the new, wet slab working from the house outward (since the first concrete laid was probably closest to the house or structure and setting up sooner.)

and if you wanted to get creative, you could break up the area with brick inserted to act also as expansion joints. Using this method you could pour 1.00 m x 1.00 m squares (.90 m x .90 m) at your leisure, one a day for example. It's not as difficult as it may sound and it leaves a very attractive and durable surface.

At about 1800 per cubic meter of C-pac/ready mix it would be quicker and easier to get it pre-mixed and brought in. The other advantage would be not having any cold joints. As mentioned, if you do it yourself you can break it up with expansion joints using a 2x4 the length or width of the slab.

Unfortunately, proper finishing tools aren't available here so getting the right finish isn't easy. The Thai method of mixing cement and water to form a paste and applying it to the surface isn't a good idea as it will almost always crack and break.

Chokedee....

Edited January 19, 2007 by excaliber

[Nawtilus]

You guys quoting 15/1800 pcm for ready mix, is that an upcountry price ?? In Bkk I have always been given prices from 2200 to 2700.

[Lancashirelad]

You guys have given the OP some excellent advice but only one has mentioned some fall (1%)

An area this size should not be laid level, but have maybe 3 - 4mm of fall going away from the house.

If you get a Thai team in to do it, you'll have to watch them for this as they generally like to lay it level, but then it will stand water when it rains.

Edited January 23, 2007 by Lancashirelad

[OneeyedJohn]

The biggest problem here is the lack of suitable tools to finish the job properly. Our patio is 8 x 7 m and I hate seeing it everyday as its one large grey area. We should have put colour and bricks in as mentioned above.

One fine day I'm gonna..................

Laying concrete is definitely not a one man job. You'll need several sturdy women folk to help

[splitlid]

to the origional poster.

the fact that your asking how to mix concrete tells me that your best off getting some one else to do the job,

all this construction jargon you have been fed by the thaivisa resident builders has surly flown over your noggin'.

DO NOT try to do it yourself. it will result in a total f"ck up.

its cheap enough to employ thais to do this job and with less sweat and tears from yourside.

[lingling]

You guys quoting 15/1800 pcm for ready mix, is that an upcountry price ?? In Bkk I have always been given prices from 2200 to 2700.

That depends on the strength and the supplier. I paid 1400 or 1450 per cubic metre for 15m³ of 325cm³ mix a couple of months ago. B2200 to 2700 sounds like you were getting extra strength concrete or concrete with some additive. (or did you order through some builder? Then you have to pay their commission too.)

[lingling]

15m³ of 325cm³

...should be 15m³ of 325kg/cm³ of course. Thanks Chownah for pointing out my typo!

[scooterboy]

Well - a big thanks to everybody that came with unbelievably good suggestions, links and excellent advice. I must admit, I never really expected such an enormous amount of replies. Got really engrossed in reading the possibilities and checking webpages. I'm loathe to admit it (more than you guys can imagine!), but you're all quite right and I bow to

your better judgement (and to the ones who've already had the back-breaking pleasure of actually doing the same sort of work).

I think I WILL leave it to others to do the job for me, seeing as this is definitely not a "handyman" sort of task to take on, which I'd rather naiivly presumed it to be. It's the steel reinforcing part that's got me beat, as there ain't no way I can tackle that particular job. Mind you, it's rather funny to think that I'm a guy with a reasonable level of intelligence,

but will have to leave the job to someone who perhaps can't read or write (no offense meant). Naturally, I will most certainly remember the tips

and get as close as I can to where the concreting is taking place, to check how and why the work is being (or will be) done as it is.

Still impressed by all your efforts - and the knowledge won't be wasted. I'm still going to try my hand at concreting, but it'll just be a tiny area (a couple of square feet or so ) at the other end of the house and it won't matter if I screw things up, there. Gotta try things out if you

want to learn something - and ain't that the truth!.

Too, others will perhaps also heed your sound advice if they need to do any concreting.

Thanks to everybody once again - y'all a great bunch of guys!!

[sfokevin]

Scooterboy!!!!... Isn't that the nickname of the Head Engineer at Suvarnabhumi Airport

There you are on the right...

Edited January 25, 2007 by sfokevin