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Hi

Can someone tellme the ratio of cement+sand +20mmjally( aggargate) for Columns concrete: lintel concrete: roof concrete:Chajja
In what ratio they should be mixed..

Iam buying Birla 53 grade


Thanks
velu

Concrete mix - Ratio - 1:2:3 (cement:Jalli:Sand)
Inside palstering - Ratio - 1:6 (cement:Sand)
Outside plastering - Ratio - 1:4 (cement:Sand)

More details - Check Bharti Cements website technical section.

thanks

Hi Velu
Concrete mix is mentioned in the structural details as m15/m20/m25 etc....
M-15 = 1:2:4 (cement:sand:stone aggregate)
m-20= 1:1.5:3 (cement:sand:stone aggregate)
m-25= 1:1:2 (cement:sand:stone aggregate)
Depending up on the slab spans ,beam lengths,loads etc..civil engineers design the concrete mix.In general constructions M20 is good enough.

Regards
Ar.Praveen.N
Ardes Architects and Interior Designers
www.ardesarchitects.com

Hi
I was told that 1:1.5: 3 ratio of m20 has

1 unit of cement
1.5 unit of sand and
3 unit of 20 mm jalli

But I see that in above posts, the order is reversed. i.e. 1.5 unit of Jalli and 3 unit of sand.

My contractor follows the following proportion for all concreting works

1 bag of cement -> has 4 pots of cement
10 pots of river sand
10 pots of 20 mm jalli
4 pots of 12 mm jalli

So the resultant mix is 1(cement):2.5(sand):3.5(Jalli) and he says most of the contractors use 1(cement):3(sand):4(jalli). Birla super 53 grade OPC is used.

Is this acceptable structurally and is this a common practice ?

Thank you,
Selva

MK, most of the contractors use the proportion as you mentuoned. They did the same thing in our ongoing project too. I noticed that and brought it to the notice of my architect. This proportion is not correct. I asked my contractor to follow the correct proportion or quit. He has changed the mixing proportion since then and I see a better quality concrete now visually too. Even though he says he is following the instrction I think he has changed only little bit.

So, please ask him to go with propoer M20 specification.

During the RCC roofing recently my contractor was using 9 pots of sand and 10 pots of 20 mm Jalli for 1 bag of Cement. Going through the post, I see that its not the optimal mix.
I just saw this inormation in the Bharti Cement Technical support section: "Concrete: The ideal ratio of the concrete mixture should be 1:1½:3 (1 cement: 1½ sand:3 aggregate)." which might be incorrect as everywhere else I see the ratio as 1:1.5 Stones and 3 Sand, and also as indicated by Ar.Praveen.N..
For RCC I was using ACC Concrete Plus cement. Is the mixing ratio different for different brands of cement? Can anyone please shed some more light on this topic?

One of my architect friends says , 1:1.5:3 / 1:2:4 refers to cement : sand : jalli. I also checked with some contractors who agree with it. Praveen should pls clarify.

Hi,
Its my typo mistake in the previous post,sorry about it.Hope i haven't damaged some ones work.
The ratio is always cement :Sand :jalli
M20 in theory its - 1:1.5:3 but in practical they make 1:2:3 to avoid honey combs .Less the sand more the honey combs .The jalli will not settle properly in case of less sand.

Regards
Ar.Praveen.N
Ardes Architects and Interior Designers
www.ardesarchitects.com

I am not getting clear as it states we need to use M20 mix for RCC, but about others like

1. Columns mix + with size of steel to use
2. Beams mix + with size of steel to use)
3. lintel concrete + steel size to use:
4 .roof concrete : Already mentioned (M20 proportion) but can anybody mention the size of steel to use -
5.Chajja Mix :
6.internal flooring (Any steel to use)
7.External flooring. (any steel to use)
8.Belt mix for foundation with size of steel to use ( if brick foundation is not used only Belt foundation)

Anybody please give the same as it would help everybody to propose this model