Concrete Pixels

About 70% of concrete volume is made up of aggreggates of various sizes from less than 1 mm up to 64mm or even more although in normal construction a maximum size of 20-32mm is used. One of the most important consideration when combining different sizes of aggregates is the distribution on how much of each type should be. The optimum distribution has to be achieved inorder to achieve maximum packing with least void spaces that would at the sametime provide the required concrete properties. In most cases, current practice is just by adjusting manually the composition and comparing it to the target sieve lines define by the standards. Basically it’s a trial and error approach that would seem easy for experienced mix designers. Recently I have come into one technical paper that uses Fuller’s “ideal” curve equation. First, an ideal curve is determined based on the maximum size of aggregate and the sieve sizes. Second, the actual sieve curve is determined based on the simple sieve analysiswith the predetermined amount of each aggregate size. Third the ideal and the actual sieve lines are plotted and the problem is solved by minimizing the deflection of the actual sieve line to that of the ideal one. I have tried it using the excel functions to and results are very convincing.