Sir, my question is, if we mention the concrete mix grade as M20 for columns of a residential building (say G+1 storeys) then the mix proportion as per IS 456-2000 code is 1:15:3 (Cement:Fine aggregate:Coarse aggregate). As for residential building projects in rural and suburban areas, the concrete is prepared in site by volume batching using mortar pan (ghamela). When i asked the mason for how many number of pans (the size used generally during concrete casting) does a 50 kg cement bag fills, he replied me 3. According to this, as per IS code, for each time of mixing the concrete of M20 grade in concrete mixer, it is required to add 3 pans of cement (equals to one bag of 50 kg cement), 4.5 pans of sand and 9 pans of aggregate (kankar). But, the local mason uses the ratio as 1 bag (50 kg cement): 7 pans (sand): 8 pans (aggregate) which is not matching the recommended mix proportion as per IS Code. When i asked him to follow the mix ratio as per the IS Code, he said that the concrete will look like more in aggregate and porous. So to account this, they go with their method of concrete ratio. So, 1. How does this affect the structure and how to consider such real time concerns while designing the structure? 2. Which one is right? 3. Any suggestions......?