ready mix concrete vs manual mix

[girishik]

Dear All,

Please some provide info on the ready mix concrete vs manual mix. I confuused with which one should I go.

Regards,
Girish IK

[arjun.surendra04]

Unless you have a huge requirement avoid ready mix. Things at construction site should be in perfect state for these trucks to come pump the mix. Usually there are some or the other thing that will cause delay in pouring the mix and this will cause problem as the trucks block the road and they start complaining. When I mean manual mix it's going to be a diesel based mixer a lift and team of workmen. It takes a day to cover 2400 roof in manual process. Mix quality can be physically monitored. If I am not mistaken ready mix is costlier for small area.

[kpb2308]

I used RMC for footings. Recommended grade was M20. I got M17 on 7 day test, and M24 on 28 day test. Later someone told me, they had brought separate concrete in a bag and put that in the testing cubes. I have also heard they do not use good input materials. Example, for sand, they use half quary dust and half sand. So, for my GF roof, I decided on gang mixing. Recommended mix was M25. I stood the whole day at site and ensured they put the required quantity of sand, cement and jelly. The 7 day report shows M25. Need to still get the 28 day test.
My advise, if you have the time to monitor properly for one day, go for manual mixing.
Even the structural engineer said he prefers manual mixing.

[m3_07]

I used RMC for footings. Recommended grade was M20. I got M17 on 7 day test, and M24 on 28 day test.

Which company was this???


Also, in RMCs, you do not have a control on the quality of the materials they use. RMC issues get compounded by the chemicals they use to harden the concrete.

[kpb2308]

m3_07, I used Hitec concrete, which was recommended by my contractor.

[saisuraksha]

@ Girish,

Even i was in a same state to go for Manual mixing or Ready mix i did few research and Here are the same.

Ready mix : it was costing Rs 2400 approx for 1 cubic meter and we may require 14 cubic meters including beams for a 30 x 40 site

R M Concrete is a mixture of 50% cement , robo sand, natural sand and fine 6mm to 12 mm stones along with this they will be mixing GGBS (google it) , apart from concrete charges there is soming called pumping charges involved this charge is to deliver the concrete to the place from the vechical

ACC case it was very high and its 25k they were asking rest all companies were are also asking pumping charges ranging from 7k to 10k.
Ultra tech said they will not disclose the mixture and they will give a certificate after 28 days what would be the strength.

After doing all the research i found there will be 20k difference per molding between RMC and Manual execution
but every one suggested to go for Manual mixing and no one is incline to RMC.

[yadavprabha]

so My thoughts from fresh experiance , just 2 weeks ago.

1. Sand Mix is any day better , you will end up spending 15-20 k extra and more work in terms on montoring the mix and the labourers all the while.

2. RMC GGBS is costly (4200 rs Per CM) and i have got this for the Ground Floor Slab, and my experiance is full of Cracks...all across and water is leaking as we cure....not a good sign at all ,. the RMC india guy told me ...he will put some chemical ....but not good experiance..

3. Then FF Slab i did manual Mix , it was good....effort is more for sure and cost on upper side by 15-20k ...but worth it....if you are monitor, no Cracks...

5. Would suggest RMC only for Footing which goes below the Ground....

let me know if any more details ...as these are fresh in my mind..

[Nivas]

yadavprabha,
Thanks for sharing your experiences, I was contemplating RMC for my roof slab ,do you think 100% OPC RMC would have done better, do you know the cost difference b/n GGBS and 100% opc ? Was vibrator used during the pouring as you mentioned leaks?

[yadavprabha]

Nivas, the GGBS was around 3800 is the last quote and the 100% ops was 4200, yes Vibrator was used all the while while pouring.

ok GGBS is better ...
So i my earlier post i had told i went for GGBS, which is wrong sorry i had gone for 100% OPC since my engineer told it will be strong, But the RMC guy told me ...it is better i go for GGBS. but i went with what my engineer said. s0 100% opc is always Costiler.