HOW TO DO SAMPLING OF CEMENT FROM BAGS?

While sampling cement from a lot (consisting of a number of cement bags), the lot is divided into a number of sub-lots.

Number of sub-lots into which a lot is to be divided is depends upon the weight of the lot. Use the following table while dividing the lot into sub-lots.

Take sample from at least 2% of the bags subject to minimum of five. Randomly choose a minimum 5 no. of bags from sub-lot. Use the following procedure to select bags randomly.

Procedure for Random Sampling to Select Bags from Sub-lot

• First count the number of bags in a sub-lot. Let it be “N”.
• Then decide how many bags you need to sample. As a guide a minimum of 5 no of bags should be selected.
• Divide the total no of bags (i.e. N) with the no of bags to be sampled (i.e. N/5). Let it be “x”.
• Now starting from any bag at random, count the bags in the sub-lot in one order as 1, 2, 3 up to x and so on. Every x^th bag so counted shall be removed.

Taking Samples from the Bags

• Insert the sampling tube (as shown in the figure above) diagonally into the valve of the bag and place your thumb over the air hole and then withdraw the sampling tube.
• Take approximately equal number of increments from each of the bags as selected above.
• Weight of each increment should not be less than 2 kg.

Packing of Sample

• Store the sample as selected above in a moisture proof, air-tight containers to avoid moisture absorption and aeration of the sample.
• If want to store the samples in can, then completely fill the can and seal it immediately.
• The containers must carry suitable identification marks so that they can be related back to the particular sub-lot from which the gross sample has been taken.