This is more of a theoretical question, I’d like to learn more about the nature of concrete.
Is the purpose of gravel in concrete for strength? What would concrete consisting of only sand & cement be like (simply replacing the gravel volume with sand). Generally I thought that increasing the ratio of cement to total aggregate (sand & stone) increased the strength as well.
Replies
Having a gradation of aggregate will give the best concrete.
yes, I understand that, but why? What function does the aggregate serve in the concrete? Is there anyone on here that works for a ready mix plant?
Strength, durability and surface hardness. Cement is very soft. Sand will not wear nearly as good as coarse aggregate. You will use much more cement in a sand and cement paste. Gradation reduces spaces between larger aggregate
Gradation affects the strength of concrete
Gradation helps to reduce shrinkage crackshttp://www.cement.org/ will give you every answer you need.
Edited 4/30/2006 5:09 pm by gb93433
The powerpoint file is a short part of a lecture I give on concrete.
I'm sure there are folks on here who know alot more about concrete than i ever will but i think i have every book and web page about concrete maked or read... i do alot of concrete alot of molds stamps forms and just flat work... makes you feel like god... who else can make ROCK ? :)
portland sand & lime = mortar the more lime the lower psi the less portland the lower the psi... the higher the portland to sand the higher psi (type O N & S ect...)
add rock and take away the lime... thats concrete in theory you want every void filled so it takes different size rock to join & fit together ... if you just had sand(ie fine rock) & portland... no matter what your portand ratio it wouldn't be very strong...
once your aggregate ratio is correct (fine sand & everything bigger) the amount of portland added increases the strength of the final product... the less water you use also makes it stronger... an almost dry hard to work mix will be much stronger than a wet liquid mix... if you need a liquid mix then you need to make up for it with more portland...
all this is just general rules... there is air... ad mixtures... pressure, heat, ect ..that all can come into play...
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Thanks everyone. That's what I was looking for.