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[targus]

thread bookmarked!

[Rory Phoulorie]

footing, columns and ground beams all to be done with ready-mix.

Request the ready-mix concrete supplier to prepare a set of four test specimens (cube or cylinder, depending on what is specified) for you to test at an independent testing agency (CARIRI, Geotech, Trintoplan, UWI, etc.). One specimen should be tested at 7 days (this test should yield at least 60% of the specified 28 day compressive strength), two specimens tested at 28 days and one specimen kept as a spare. Please ensure that you know what strength (cube strength or cylinder strength) you need for your concrete.

I know u mean well and this is prob the way to go....but srsly...do u think anyone actually does this?

Yes, people do actually test the compressive strength of the concrete. When you compare the thousands of dollars that you spend on a truckload of concrete to the hundreds of dollars that you spend to test the concrete, you realise it is a very worthwhile investment.

One thing I forgot to add to that list of things to be aware of in my previous post is that the OP should invest in a good quality concrete vibrator (locally known as a concrete poker).

He/she should not use reinforcing steel rods to "poke" the concrete in order to remove air voids from it. He/she should also not use the concrete vibrator to move the concrete in the forms/excavations. He/she should not allow the concrete to drop over a height greater than 1.5m (5ft). He/she should use chutes or tremie pipes to place the concrete in the desired location.

After the concrete has been placed and finished in the desired location, a sheet of polythene should be placed over the concrete to prevent rapid evaporation of water from the concrete (rapid water loss can lead to shrinkage cracks in the concrete). He/she should try and keep the concrete wet for at least three days after the concrete has been placed.

[ibanez]

Concrete supplier has a vibrator poker so that's sorted!

Can the footing and column be poured at the same time?

It's a 3 ft column from the footing up towards the ground beam!

[pete]

What if the sample they give you fails the 7 day or 28 day test, will the concrete supplier be liable for replacing all that had been poured as well as the labour to remove it?

[crazybalhead]

Excellent question.

[Rory Phoulorie]

Can the footing and column be poured at the same time?
It's a 3 ft column from the footing up towards the ground beam!

That may be difficult. If you try to pour the concrete for the column at the same time that the footing is being poured, what may happen is that when you start to pour and vibrate the concrete in the column, the concrete that is already in the footing may get displaced out of its own formwork. What you may have to do is let the concrete in the footing set for a few hours before you come back and pour the column later the same day.

What if the sample they give you fails the 7 day or 28 day test, will the concrete supplier be liable for replacing all that had been poured as well as the labour to remove it?

Usually when you specify concrete strength, it is based on the 28 day strength. The 7 day test is done to get an early indication of whether the concrete will achieve the specified 28 day strength. The 7 day strength is usually around 60% of the 28 day strength, but this is dependent on what admixtures are used in the concrete mix.

Readymix concrete companies in Trinidad usually prepare their own test specimens as part of their quality control operations. In all my years of engineering, I have seen only one company ever admit that they supplied bad batches of concrete and accepted liability. There is a prominent "readymix" concrete company that will never admit they supplied poor quality concrete. That is why I recommended that the OP get the readymix concrete supplier to prepare test specimens for him/her and to have them tested at an independent testing agency.

All these readymix concrete companies in Trinidad tout that they supply concrete meeting ASTM and BS requirements. Yet when you request from them their quality control records which are to be kept in a format that will allow a proper statistical analysis of the various grades of concrete that they produce as specified by ASTM and BS, they cannot produce this information. When you request from them quality control records showing that the aggregates that they use in their concrete mixes meet the ASTM and BS requirements, they provide you with a set of test results from National Quarries Company Limited which do not comprise the full battery of tests required. Hardly any of them do their own quality control testing of aggregates. They rely on the test results provided by the aggregate supplier. Go ask any one of them to see the Potential Alkali-Silica Reactivity test results for their aggregates and I can assure you that none of them could produce this test result.

[*$kїđž!™]

footing, columns and ground beams all to be done with ready-mix.

Request the ready-mix concrete supplier to prepare a set of four test specimens (cube or cylinder, depending on what is specified) for you to test at an independent testing agency (CARIRI, Geotech, Trintoplan, UWI, etc.). One specimen should be tested at 7 days (this test should yield at least 60% of the specified 28 day compressive strength), two specimens tested at 28 days and one specimen kept as a spare. Please ensure that you know what strength (cube strength or cylinder strength) you need for your concrete.

I know u mean well and this is prob the way to go....but srsly...do u think anyone actually does this?

Yes, people do actually test the compressive strength of the concrete. When you compare the thousands of dollars that you spend on a truckload of concrete to the hundreds of dollars that you spend to test the concrete, you realise it is a very worthwhile investment.

One thing I forgot to add to that list of things to be aware of in my previous post is that the OP should invest in a good quality concrete vibrator (locally known as a concrete poker).

He/she should not use reinforcing steel rods to "poke" the concrete in order to remove air voids from it. He/she should also not use the concrete vibrator to move the concrete in the forms/excavations. He/she should not allow the concrete to drop over a height greater than 1.5m (5ft). He/she should use chutes or tremie pipes to place the concrete in the desired location.

After the concrete has been placed and finished in the desired location, a sheet of polythene should be placed over the concrete to prevent rapid evaporation of water from the concrete (rapid water loss can lead to shrinkage cracks in the concrete). He/she should try and keep the concrete wet for at least three days after the concrete has been placed.

really good advice rory....

[rfari]

Rory, any reviews on kalcrete wrt mix quality?

[Rory Phoulorie]

Rory, any reviews on kalcrete wrt mix quality?

Kalcrete is new to the readymix concrete business. I am not familiar with their operations or their technical personnel so I really am not in a position to make any comment on them. Kallco (the construction company) was a subcontractor on a project that I worked on, and while they had some good equipment, they did not have experienced supervisors to guide the field operations.

Things that you need to look out for with new operations like Kalcrete are:

1) Condition of their batching plant - Are the scales calibrated? Is the moisture sensor calibrated?

2) Condition of the inside of the drums of their concrete trucks.

3) Find out the target strength for the various grades of concrete they produce. Even though the 28 day compressive strength of the concrete may be, say, 28MPa (4000psi), the target strength is usually higher to account for any variations in cement and aggregate quality and mixing proportions. Essentially, a safety factor is built into the concrete compressive strength.

4) Request from them quality control test certificates for the aggregates (coarse and fine) that they use. Review these test certificates against the relevant ASTM or BS requirements.

5) Request from them manufacturer's test certificates for the cement that they use. The test certificate will usually indicate what is the reference test standard (ASTM or BS) that the cement was manufactured to.

6) Ensure that all the mixing water for the concrete mix is added at the batch plant. DO NOT allow them to add mixing water at the site to get the mix more workable (i.e., less stiff). If the mix is too stiff, then ensure that they add plasticiser to the mix and NOT water.

That's about all I could think of off the top of my head.

[rfari]

Nice. Good stuff. I spoke to one of the apparent owners over the phone earlier this year to enquire on the 3000 and 4000 psi cements and both were about 750 -800 tt/cu m (I have to find the email). Ready mix was about 1200 so it raised my brow

[crazybalhead]

rory, where yuh wukkin?

[pioneer]

There's a guy from central who "made" french windows for a cousin of mine, within a short time all the hinges started breaking off. Person refused to offer any service/support/liability.

Solution - Abel

[ibanez]

Concrete for ground beams and columns poured yesterday!

All went well, sufficient coverage on all steel work!

Foundation blocks next!

[Rory Phoulorie]

. . . .Foundation blocks next!

Which manufacturer's foundation blocks are you purchasing? You should ensure that the blocks are manufactured and tested to some internationally accepted standard (ASTM or BS). I believe that Bestcrete/Abel and Coosal's do indeed actually test their blocks to ensure compliance with such standards. I am not sure about the other block manufacturers.

Every Tom, Dick and Harrilal are buying concrete batch plants and block making machines without having proper knowledge about the quality control processes involved in concrete block manufacturing.

[ibanez]

^^
Bestcrete

[ibanez]

Foundation blocks layed and loaded!

Backfilling to be done next.

The existing dirt dug from the trenches and butts etc, will be used for backfill.

However, there was a downpour of rain on Friday into the night which really 'messed up' the place.

Any advice on how this dirt should be spread and left to dry, before any more dirt is to be placed on top of it?

[Rory Phoulorie]

What type of dirt is it? A sandy (grainy) soil? Or a clayey (sticky) soil?

Backfill soils should be compacted in layers not exceeding 200mm thick (loose). They should not be compacted in a wet state. If it is wet, it should be spread out and left to dry out. It should also not be completely dry. It should be compacted in a damp state. A rule of thumb is that the soil should be compacted until the compaction equipment leaves no significant marks in the backfill (indicating that it is well compacted).

Sandy soils should be compacted with a plate compactor (known locally as a Wacker plate compactor).

Clayey soils should be compacted with a rammer compactor or pad foot compactor (known locally as a jumping jack compactor).

[ibanez]

The dirt is clayey soil, but really 'firm'! Will be adding 'sand dirt' or 'overburden' to complete the back-filling process!

Can someone explain what exactly is 'overburden', is a layer of red sand required on top of either?

Thanks

[Rahtid]

Yes contact Elvis, he is best in construction. I had another contractor that built my house, i had a foundation crack that caused my house to shift. The foundation split in half, Elvis did a great job in saving my house by doing some major foundation repairs. He is also reasonable and yes Rahtid is his tuner name.

heard elvis tell this story.....

Interesting.

1uhh

Thnx ECIGGTT

cyah plz everybody tho,

[Bizzare]

cyah plz everybody tho,

this is the sad truth for every tradesman

[Rory Phoulorie]

The dirt is clayey soil, but really 'firm'! Will be adding 'sand dirt' or 'overburden' to complete the back-filling process!

Can someone explain what exactly is 'overburden', is a layer of red sand required on top of either?

Thanks

Overburden is the term used to describe a layer of material that overlays the material that you actually want to mine in a quarry.

With respect to your home construction, I am assuming that you are backfilling to facilitate construction of the ground floor slab. What you should use beneath the concrete slab is a layer of 0.15mm thick (500 gauge) polythene vapour barrier, 50mm thick red sand blinding and 200mm thick hardcore (well graded crushed "blue" limestone is ideal). Beneath the hardcore you would have the overburden backfill.

[rspann]

I noticed that you said the soil was clayey,was it sapatay(usually found in southern areas)If so did you auger /pile the foundation?

[ibanez]

Nah not sapatay. Yes I did auger/pile the foundation.

I'm doing everything according to my building plan!

[solidust]

Hey

Anyone ever went through or did business with Wilsonartstt?

http://www.wilsonartstt.com/