How to do concrete melt weight

First of all, correct your concept: it's "capacity" not "melt weight";

According to the regulations: use a 20L "capacity bucket": first self-calibrate the actual volume V and weigh its own weight P. Then, fill the concrete to be measured in two batches, insert and pound the concrete. Volume V and weigh its own weight P, the specific method and process, you should know, do not repeat;

Then, two times full of concrete to be measured, inserted after pounding dense, scraping and wipe the outer wall of the barrel, weighing P1; and then pour the concrete out of the empty barrel, clean out the empty barrel, and then refill the concrete to be measured, steps, methods, the same as the previous; weighing P2;

Calculation: (P1+P2) / 2V -2P)/2V, the result is converted into kg / cubic meter, accurate to 10kg / cubic meter.