Building A House In Chiang Mai At The Worst Possible Time

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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby Greenside » Sat May 18, 2013 8:14 am

Our contract has the slump test results on three or four of the batches we used so far.

Watch the water?
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby Mike Judd » Sat May 18, 2013 12:40 pm

I don't mean the water in the dam etc;? the water that they try to add to the mix ! but if you are lucky enough to be having Slump tests before they pour ,max !00m.m. you should be O.K.
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby Greenside » Sat May 18, 2013 1:12 pm

You've lost me, Mike. The concrete turns up in the truck and they pour it - at what stage (and why) does who try to add water? BTW the slump tests are done on material taken from the batch as it is being delivered (or what use would they be?) and the results of the compression tests come in over the following 28 days as the samples cure. CPAC sends their guy round to do it and issues a certificate to the contractor who gives my architect a copy.

Exactly what would happen if a batch proved significantly defective remains to be seen but at least you'd know there was a potential issue.
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby pipoz » Sat May 18, 2013 1:32 pm

Greenside wrote:You've lost me, Mike. The concrete turns up in the truck and they pour it - at what stage (and why) does who try to add water? BTW the slump tests are done on material taken from the batch as it is being delivered (or what use would they be?) and the results of the compression tests come in over the following 28 days as the samples cure. CPAC sends their guy round to do it and issues a certificate to the contractor who gives my architect a copy.Exactly what would happen if a batch proved significantly defective remains to be seen but at least you'd know there was a potential issue.


Normally you would want to have/like to get a concrete slump of around 150 mm when the truck arrives at site, but given this is Thailand, you will probably find that it is closer to 180 mm, when it leaves the batching plant and first arrives at your site. No big deal.

If after arriving at your site, they then add some more water to the truck (so that it is easier for them to place/spread out) and push the slump up to 200 mm, again it is no big deal. The affect on your long term concrete strength is marginal at the end of the 28 days. Adding some additional water (but not a 44 gallon drum of it) to the truck at site, just means the concrete will then a bit take longer to reach its theoretical 7 day design strength, but it will in all likelihood it will still reach its design strength after 28 days.

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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby Greenside » Sat May 18, 2013 2:58 pm

Thanks for the explanation. :)

The concrete is poured without any additions at the site but I know that when they were casting the pool walls for example we ordered a wetter mix to make the job easier. The forms just arrived - bang on time!
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby pipoz » Sat May 18, 2013 3:18 pm

Thats ok Greensdie, I seriously doubt that you will have any problems with a wet mix.

I have seen plenty of concrete mixes arrive on a site and they were nearly soup when they came out of the truck and at the end of the day (a month later) they still achieved their desired strength.

Likewise, I have also seen many concrete slabs, columns and walls poured, without any form of curing and unless you are in a extremely dry hot climate its not normally a structural concern. Sure the concrete outer surface might go a bit chaukly (without the wrapping/curing), but the 28 days strength is not greatly affected. Best bet, just leave the formwork on for a week then strip them.

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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby MGV12 » Sat May 18, 2013 3:36 pm

pipoz wrote:Thats ok Greensdie, I seriously doubt that you will have any problems with a wet mix.

I have seen plenty of concrete mixes arrive on a site and they were nearly soup when they came out of the truck and at the end of the day (a month later) they still achieved their desired strength.

Likewise, I have also seen many concrete slabs, columns and walls poured, without any form of curing and unless you are in a extremely dry hot climate its not normally a structural concern. Sure the concrete outer surface might go a bit chaukly (without the wrapping/curing), but the 28 days strength is not greatly affected. Best bet, just leave the formwork on for a week then strip them.

pipoz


How unusual ... positive comments about Thai pre-mix ...

Maybe this lurks somewhere in your 187 posts ... where does your knowledge/experience in concrete come from?

“Some days I am an optimistic pessimist ... other days I am a pessimistic optimist”
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby Roger Ramjet » Sat May 18, 2013 3:58 pm

I think people are missing a very valid point to do with concrete coming out like water. The reason so many people complain about the mix is because they are pouring it without plastic sheeting lade and the soup disappears into the surrounding soil, which makes the surrounding soil very strong, but your slab very weak. However if the formwork has been done properly for columns and beams there should be little loss. If the concrete is poured for a slab on the ground, then plastic should be used under the slab, unfortunately I know few people who use black plastic, me being the exception: viewtopic.php?f=3&t=1864&start=2040
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby pipoz » Sat May 18, 2013 4:03 pm

Granted Roger and agree a VP Membrane under a slab on ground is a must, but he did pour his up on a precast plank deck from what I could see

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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby pipoz » Sat May 18, 2013 4:13 pm

MGV12 wrote:[
How unusual ... positive comments about Thai pre-mix ...Maybe this lurks somewhere in your 187 posts ... where does your knowledge/experience in concrete come from?


Hi MGV12, to use a well know line, "The list is long but distinguished"

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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby MGV12 » Sat May 18, 2013 7:18 pm

pipoz wrote:
Hi MGV12, to use a well know line, "The list is long but distinguished"

pipoz


Thought they only taught air combat at the Navy's Fighter Weapons School 8)

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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby Mike Judd » Sat May 18, 2013 7:49 pm

I'am sorry,! but I can't seriously believe those comments about lots of water having no difference what's so ever with the finished strength of your concrete, just takes longer to cure.? Why bother with Slump Tests at all ? All the Engineers and Clerk of Works on the literally hundreds of building sites around the world that I have been on , must have been paranoid to insist on keeping the slump to around 100m.m. I can remember one time pouring concrete into a form 12mts long that was half the span of a bridge that was going to be craned out over a road in Sydney later. The slump was specified to be 50m.m. and we were using a Crane with a concrete bucket to do the pour, the only problem being the concrete wouldn't come out of the chute it was so dry, even with me standing up on the bucket with a crow bar, the Engineer had to be persuaded to let the driver add a bit more water. This was for a high strength precast piece of concrete and not your usual ordinary slab, but the general rule still is , the more cement in the mix, the stronger it will be,and the more water other than what is required to start the chemical action and a reasonable flow, the weaker it will turn out. I have no wish to tell anyone how they should do anything, just stating plain facts.
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby pipoz » Sat May 18, 2013 8:26 pm

Mike Judd wrote:I'am sorry,! but I can't seriously believe those comments about lots of water having no difference what's so ever with the finished strength of your concrete, just takes longer to cure.? Why bother with Slump Tests at all ? All the Engineers and Clerk of Works on the literally hundreds of building sites around the world that I have been on , must have been paranoid to insist on keeping the slump to around 100m.m. I can remember one time pouring concrete into a form 12mts long that was half the span of a bridge that was going to be craned out over a road in Sydney later. The slump was specified to be 50m.m. and we were using a Crane with a concrete bucket to do the pour, the only problem being the concrete wouldn't come out of the chute it was so dry, even with me standing up on the bucket with a crow bar, the Engineer had to be persuaded to let the driver add a bit more water. This was for a high strength precast piece of concrete and not your usual ordinary slab, but the general rule still is , the more cement in the mix, the stronger it will be,and the more water other than what is required to start the chemical action and a reasonable flow, the weaker it will turn out. I have no wish to tell anyone how they should do anything, just stating plain facts.


Mike you might read what I said more carefully, nobody said "having No Difference what so ever". I said the effect is marginal at the end of the 28 days, for a slightly greater slump of say 20mm more.

Quote: "Normally you would want to have/like to get a concrete slump of around 150 mm when the truck arrives at site, but given this is Thailand, you will probably find that it is closer to 180 mm, when it leaves the batching plant and first arrives at your site. No big deal. If after arriving at your site, they then add some more water to the truck (so that it is easier for them to place/spread out) and push the slump up to 200 mm, again it is no big deal. The affect on your long term concrete strength is marginal at the end of the 28 days"

We work with high slumps over here all the time and 150mm is common for our pump mixes and acceptable to the design engineers, who by the way are Internationals/Expats. 100mm slumps or less may be the desired norm in the west, but then again the west is always ultra conservative.

Also my comments were relevant to him building a house, not a bridge or any other large scale commercial structure. He is simply building a residential house slab for normal foot traffic and in that context even if he were to achieve a slighly lesser strenth at the end of his 28 days, as no one designs to the limit, hence "no big deal.”.
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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby pipoz » Sat May 18, 2013 8:44 pm

[quote="MGV12"][quote="pipoz"]

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Re: Building A House In Chiang Mai At The Worst Possible Tim

Postby Mike Judd » Sun May 19, 2013 7:56 am

I might have got off on the wrong foot here, my original comment was because I have experienced concrete coming out of Cpac trucks in Thailand with so much water that if it wasn't for the forms there would be just the sand and metal left lying there. With all respect, I think most Members would agree that the Thai's love lots of water in the mix, it's so much easier for them. T.I.T.
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