Sampling Rate of concrete 1

[sag04]

A recent article I had gone through about concrete cubes specifies
Sampling Rate /Quantity of concrete to be represented by each sample
Column, Shear Wall -- 10 cum
Solid Raft, Pile Caps and mass concrete -- 100 cum
All other type or parts --- 25 cum

From each sample of concrete taken 2 cubes shall be made
please comment
Thank you all

 

[BigH]

Sag4 - it all depends on your jurisdiction, your specifications, etc. I'll put in the Indian Highway Standards approach - then others will/can give for other jurisdictions (I can't remember exact numbers in Canada).
Concrete volume poured (each class of concrete each day)
(in case same class is going to different sites) but normally, say at one site:

1-5m3 - 1 set
6-15m3 - 1 set more (2)
16-25m3 - 1 set more (3)
26-50m3 - 1 set more (4)
Each added 50m3 - 1 set more (5, 6, 7, depending)

Now don't asked about 15.5m3 - use your judgmenet.
They have a requirement for a "test result" to be the average of three cubes. AAHSTO Bridge codes requires the test result to be the average of two cylinders (and a cylinder for 7 days = 3 cylinders cast per set/sample).
So a set must be 3 cubes - but that is only for 28 days. Add a cube or two (our contractors add 3) for 7 days strengths (to see if you are likely to achieve the required strength). If you want a cube for early stripping (say at 1-day) add a cube. If you want a 14 day result, add a cube - if you want a 56 day, add a cube - the number you cast depends on your needs but you must have 3 (or two, whichever applies to your spec).

 

[dbuzz]

We would typicaly specify the sampling rates:
- Footings 1 per 25 cum (at least 1 per building)
- Ground slabs 1 per 25 cum (at least 1 per slab)
- Columns 1 per 5 cum (at least 1 per building)
- Beams 1 per 25 cum (at least 1 per building)
- Walls 1 per 25 cum (at least 1 per building)
- Suspended slabs 1 per 25 cum (at least 1 per slab)

Each sample would typically consist of a slump test and three cylinders (one for testing at 2 days, one at 7 days and one at 28 days).

 

[BigH]

dbuzz - where? Good idea if we give 'locales' - good info. A lot less stringent than in India's Ministry of Surface Transport. I found my "old" CSA CAN3-A23.1-M77 (since superceeded) and the frequency given is:
"... one strength test for each 100m3 of concrete placed and in no case shall there be less than one test for each class of concrete or each separate type of structural component,..., placed on any one day." Also, permits waiving if under 50m3 if there is adequate evidence of satisfactory strength is provided.
For Canada, this is assuming commercial batch plants providing concrete all over the city (I opine) - in India, where is is much more frequent, you might run into portable site mixers, project-dedicated batch plant, etc.

 

[dbuzz]

BigH, those rates are for work in Australia's mining, minerals processing and chemicals industries.