Cement : how hard is it to make ?

[Perota]

I'm in the process to transform the jungle around the house into a nice garden. Some jobs I do, some jobs I ask for professional help. One thing I don't understand is why cement work is so expensive.

I need to build a small spill over dam. The quotation I got for the job are surreal so I just wonder how hard it is and if I can just do it myself.

Does anybody has experience of this kind of job in Thailand ? the do and don'ts of making cement ...

Thanks in advance


PJ




PS : I start this thread in "farming" because it's about outdoor work, but if mods think it belongs to "construction", feel free to move it.

[somtamslap]

Assuming you mean concrete, it's hard graft in this climate because it dries out so bastard quickly..employ a couple of locals to help you..200bt a day would do it..

[dirtydog]

One thing I don't understand is why cement work is so expensive.

It isn't just cement work, first a wooden form needs to be made, then rebar cut and tied, then comes your cement work.

[ENT]

^ Just don't piss in the mix, weakens it.

[DaffyDuck]

I'm in the process to transform the jungle around the house into a nice garden. Some jobs I do, some jobs I ask for professional help. One thing I don't understand is why cement work is so expensive.

I need to build a small spill over dam. The quotation I got for the job are surreal so I just wonder how hard it is and if I can just do it myself.

Does anybody has experience of this kind of job in Thailand ? the do and don'ts of making cement ...
.

Unless you really know what you are doing, you should leave cement work to professionals, or those who do know what they are doing -- from elemental preparations, to setting up foundation and framework, to the right mix, and finally to proper treatment during setting.

[Perota]

One thing I don't understand is why cement work is so expensive.

It isn't just cement work, first a wooden form needs to be made, then rebar cut and tied, then comes your cement work.

That, I've more or less worked out. But what makes the difference between a good and a bad job ?
In theory it doesn't sound that difficult. Where is the trick ?

[FlyFree]

There's nothing difficult about concrete work, if you keep to a few basics. All the info you need will be available on the net (not forums) to do the job yourself.

[baldrick]

the screeing , finishing and good levels require the skills

a small spillway will not require much skill , just labour

[Loy Toy]

There's nothing difficult about concrete work,

Apart from the effort needed during mixing, pouring and levelling.

If you are doing the form work make sure you follow proper procedures and to eliminate the back breaking work get in a Ready~mix and do the floating work yourself. Also be sure you have a nice long, straight wooden plank and a 2 metre spirit level.

[Perota]

the screeing , finishing and good levels require the skills

In plain English please ?

a small spillway will not require much skill , just labour

That's what I'm thinking too but my contractor doesn't seem to agree and insist for charging an obscene amount for this small job .

As FlyFree suggested, I searched the web but found nothing really related to my problem. I guess it's going to be a "trial and error" process.


And some people say life in Isaan is boring ...

[Perota]

If you are doing the form work make sure you follow proper procedures ...

The proper procedures being ?

[somtamslap]

In plain English please ?

..making it look nice..

[Loy Toy]

The proper procedures being ?

1. Make sure the subsoil is levelled and compacted.
2. Prepare your wooden framewok to the pattern you wish to concrete and preferably using wood the same thickness as the concrete slab you wish to pour, ie 75mm slab use 75mm thickness wood framework.
3. When your framework is set and firmly secured by way of pegs and levelled with a slight slope where you want the rainwater to run away too lay a thin layer of sand about 1cm thick on top of your impacted soil.
4. I always then spray the ground with insecticide to kill off any bugs and ants particularly for a house slab and leave it for at least 24 hours.
5. Before you pour the concrete spray the sand with a little water.
6. Lay your reo steel on bar stools so as the reo will position itself in the middle of the final slab thickness.
6. Then pour your concrete making sure you vibrate the mix down around the reo steel at the same time achieving a full and even slab thickness.
6. After you have poured and levelled your slab and done the finishing work spray the slab with water prepeatedly over the couse of 24 hours so as to lessen the effect of cracking due to the hot climate here.

[jandajoy]

A good report LT.

What's the go on expansion gaps, or whatever they're called?

[Loy Toy]

What's the go on expansion gaps, or whatever they're called?

For a large slab like a heavy traffic area such as a 4 metre wide driveway I usually section off the slab every 2~3 metres by placing a long copper or alluminium flat plate (4mm thick ) across the width of the driveway which breaks the slab mass up into even sections.

For paths, etc I use the standard tar based soft expansion joints and the same ones we use in Oz.

They never seem to use them here and thats why you see some many cracked driveways.

I have also seen contractors use thick sliced cardboard as expansion joints here and I suppose that is a cheap easy way of doing the job as well.

[jandajoy]

wood would be no good I suppose. Just get eaten.

Someone told me that you could use a grinder to score lines or grooves every 2-3 meters. This way, when it did crack it would crack along these grooves.

[DrAndy]

That's what I'm thinking too but my contractor doesn't seem to agree and insist for charging an obscene amount for this small job .

from your post, you obviously don't really know what you want, in builders terms

either the contractor thinks it is going to be a very difficult job
or he thinks you can afford an exorbitant fee
or he doesn't really want the job

get a clear idea what you want and find a different builder

[Loy Toy]

wood would be no good I suppose. Just get eaten.

Come to think of it I have seen blokes use strips of masonite with success.

An expansion joint primarily forms a small gap so as your individual slab sections can expand and slip against each other without building up stress which causes cracks and distortion/ slab lifting.

How you create that small gap can be achieved by many methods using different materials but at the end of the day you want to have the best looking and straightest expansion joints as possible

Pretty much the same as preventing an earth quake.

[nedwalk]

or he doesn't really want the job

was what i used to do..and if you get the gig at least you get paid well

[DrAndy]

^ me too

I still do that and occasionally am pleasantly suprised!

[Panda]

It aint something you can learn over the internet. Spend a few days working with the concrete workers if you want to learn their techniques.

If you screw up in your preparations before the pour, concrete can be a very unforgiving medium to work with. VERY big job to fix up mistakes.

[superman]

That, I've more or less worked out. But what makes the difference between a good and a bad job ? In theory it doesn't sound that difficult. Where is the trick ?

To make good concrete you first need to know how to make it go hard. Concrete needs to be worked. In that, the more you work it, the harder it will become. Thai's pour as much water into a mix as possible, due to laziness. In the west we go by quantities, followed by a 'slump' scale. I'm sure that in professional construction in Thailand this will be adhered to also. It's an architects/engineers guide line. Too weak a 'slump' will not produce strong concrete.
Also, if concrete is to be delivered by a commercial company, find out what additives they will put into the mix. A fiber additive will produce a stronger mix.

[dirtydog]

Thai mixes are a lot less sand to the cement, ie here it would be 1 2 2 as a mix for floor, elsewhere 1 3 4.

cement sand stone.

[superman]

In the UK we work in percentages. IE, a 30-20 mix with a 10% slumpt, minimum water, + addatives, may be. Water can be added later on site when pouring. I may be wrong, but I'm sure it's a world wide practice. Yours sincerely Mr Floppy. Please Google 'Concrete Slumpt Test'. Extra water reduces the strength of concrete.

[dirtydog]

Please Google 'Concrete Slumpt Test'.

I doubt there is any such thing, but I do know what a slump test is, this is a small job so the concrete will be mixed on site, in Thailand a lot more cement is used in mixes on site, ie up to 50percent more, cement is the most expensive product, now why would Thai's use more of the most expensive product in a mix when in the UK they don't.....