huangyhg

dubai sand not suitable for concrete?
today i had an ee wander into my office and say that he heard that the aggregate for the concrete being used to build all of those high-rises in dubai had to be shipped in. he said he heard that the local sand was too old and smooth to be used as aggregate. i told him i had a tough time believing that. maybe the gradation is very narrow and so they were hauling in some different grades to mix with it. does anyone know something about this? does the smoothness of the granules matter enough to render it unuseable in concrete?
if you "heard" it on the internet, it's guilty until proven innocent.
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one run through a crusher and the percentage of angular shapes jumps to 80%. two runs get over 95%. something else may be wrong, but if the parent rock is strong and durable, then modified mixes can achieve any grading requirement.
the issue might be more due to salt content.
my understanding is that the sand is so old - it more like round pebbles than enything else. hence not good in concrete...
that is my story and i am sticking to it.
unless there was some sort of contaminant, then crushing marbles would provide an adequate material...
dik
a quick 'google' identiies a number of uae-based companies that supply concrete aggregrates.
i have worked in abu dhabi in 1992 - 1995. to my knowledge both dubai and abu dhabi get sand from al ain and the major suppliers were only two (one is al-sharafi) at that time. i had always problem with the quantities. they will always write 32 m3 supply note on truck whose body label says maximum volume 30 m3. being limited choice i had to live with them. however i had no problem with sand. i was production and quality engineer for a readymix concrete co and had coordinated numerous lab test from m/s ferguson labs (who were basically uk based). in reality the sand was well graded and up to 5mm in size, contrary to my home country in asia where it was maximum 3mm in size. so as per my knowledge sand in uae is very good.

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