There are many methods involved but. I will just enligthen u guys on the necessary steps to follow when sampling a concrete...
1) After mixing the concrete sample by the batching plant,a mixer truck is being use to carry the sample to the needed site.
2) You collet some quantity of sample from the mixer truck using a wheelbarrow,
3) The sample must be slumed(70-150mm),To check if the sample is good for casting,
4) Also the temperature of the sample is being checked using a thermometer,
5) Two moles is needed for the sampling,firstly mix the sample well using a hand trowel then pour the sample inthe mold(100m by100m in size) it has 3 holes,an iron rod is used to tamp the sample inthe molds 25times for the first layer then another 25times after filling the mold with the sample,a rubber hammer is being used to hit the edges of the molds inorder to remove Co2 from the sample and bringing out the molter ...
6)After smoothing the surface of the cube,it is being kept in a cool place to solidify
7)After 24hrs the cube which is being divided into two(7 & 28 days) due to the number of molds used in taking the sample,is being Cured by immersing it into a pond filled with water and left to cure for either 7 or 28 days .
7days from the date of casting the sample ,the cube is being tested to kwn the work rate of the sample using a compression machine,if the cube fails,the 28days will be tested at d due date for crushing,if the 28days fails also then a test kwn as Rebound Hammer will be carried out on the area which the sample was casted on...if the Rebound Hammer test fails also then that particular area will be demolished for Re-casting............By Material Engr Pezin