Multiple Truck Concrete Test. 1

[JoeManNorth]

Hey. I have a few big jobs coming up and I would like to know how many trucks I should run a concrete test (slump, air, cylinders) out of say 10 trucks. The client of course wants to save as much money as he can but I want to make sure the number of cylinders I cast is representative of what was poured. I know there's no real need to test EVEY truck.

 

[BigH]

This was a topic in one of the concrete threads about 6 to 8 months ago. Various members put in specs that they have used. In India - highway jobs go like this. 1st set for first 6m3; 2nd set if for 6 to 15m3; 3rd set for 15 to 30m3 and 4th set for 30 to 50m3. Then 1 set for each added 50m3. Other jurisdictions use other set standards - I'd have to look up Canada's - maybe tomorrow. Remember that a set of cylinders (three) is to be taken from the same truck and there is also a requirement that the samples be a composite of material taken from the 1/4, 1/2 and 3/4 points. Of course, you would do slump very near the beginning to get a handle on that particular point. Please do a search of the threads for this issue.

 

[JoeManNorth]

Thanks alot eh for the tips.

 

[chriswat]

Hi I am currently studying for a HND in construction and have a question if any one can help me with some research ideas i.e. sites to look at things ti include etc any way the question is - You are working for a consulting Engineer who has designed a cooling tower project comprising of four towers. This project will require 1200m3 of concrete in the foundations and ponds, 230m3 of concrete in the distribution structures and 1200m3 of concrete in the tower shells. The shells are to be constructed in lifts of 1.2m; there are a total of 50 lifts per tower. Describe and explain with the aid of anotated sketches the sampling, procedures and testing requirements you would specify to ensure the concrete quality is up to the standard, you should quote from BS wherever possible.

If any one can at all help I would be extremly greatfull

Many thanks in advance

 

[BigH]

The pours wouldn't be all on a singal day - and the the sampling/testing frequency are typically for a "day's work of a specific grade of concrete." Besides the frequency that I noted above for the India highway projects, the Canadian Standard CAN3-A23.1-M77 (now superceded but I don't have the new one) gives the following as the frequency (Clause 17.2.1.a and 17.2.1.2)
"Not less than one strength test shall be made for each 100m3 of concrete placed and in no case shall there be less than one test for each class of concrte or each separate type of structrual component, as designate by the Authority placed on a single day." ... "WHen the frequency of testing stipuated [above] will provide less than three tests for a given class of concrete, tests shall be made from at least three randomly selected batches." ... "Note: When the total quantities of a given calss of concrete are less than 50m3 the strength tests may be waived by the Authority if, in his judgement, adequate evidence of satisfactory strength is provided."

 

[JConc]

CSA states that a strength test should be done on each class of concrete every 100 cu. metres. There should be at least one strength test for each class of concrete placed that day, regardless of size. Today the rule is that a 30 litre concrete grab sample is to be taken between 10 and 90% of the load. A good idea is to have the initial few loads tested for plastic properties - temp,slump and air [if required] to prove consistency - and then randomly every 5th-10th load after that depending on pour speed, manpower etc. If work is critical, more frequency.