Concrete Mix Design

cunnins4

Hi folks,

As part of my final year project I need to design some mixes for beams with different size aggregates and different strengths. I've done mix design before, but things like slump, defective rate, minimum cement content and water-cement ratio were always specified in the questions.

Is there anywhere I could get info. on what sort of values I need for these? I basically have to design a 40N concrete with 10,20,40mm aggregate and the same for 50N and 60N mixes to make up non-shear reinforced concrete beams spaning ~1.5m or so. I imagine the slump wouldn't need to be very much as there's no stirrups to be worked around, but I've no clue as to what values to specify for the rest.

The mixes have to be spot on, as these beams will be built and tested so I can't have a design of 40N achieving 20N after 28 days! Don't think my supervisor'd be too happy with that!

Any guidance is appreciated!

Cheers.

godtabh

cunnins4 wrote: »

Hi folks,

As part of my final year project I need to design some mixes for beams with different size aggregates and different strengths. I've done mix design before, but things like slump, defective rate, minimum cement content and water-cement ratio were always specified in the questions.

Is there anywhere I could get info. on what sort of values I need for these? I basically have to design a 40N concrete with 10,20,40mm aggregate and the same for 50N and 60N mixes to make up non-shear reinforced concrete beams spaning ~1.5m or so. I imagine the slump wouldn't need to be very much as there's no stirrups to be worked around, but I've no clue as to what values to specify for the rest.

The mixes have to be spot on, as these beams will be built and tested so I can't have a design of 40N achieving 20N after 28 days! Don't think my supervisor'd be too happy with that!

Any guidance is appreciated!

Cheers.

There are concrete specs for this kind of thing. I had a set before but i've no idea where they are. I think i got them off roadstone

dan_d

Contact the concrete companies like Kilsaran.The structural engineer will specify those things usually, but often the mix designs are worked out in conjunction with the concrete companies, because they'll often be able to tell you what products you can add or take away to best make your concrete suit what you're pouring.They tend to be fairly willing to help, and most of them have plants here in Dublin (sorry, assuming you're in Dublin).If they can't give you definite answers, they'll certainly be able to point you in the correct direction. Slumps and ratios tend to be pretty standard, and the cement content they should certainly be able to help you with.Ask any questions, they have people who specialise in mix design.

cunnins4

dan_d wrote: »

Contact the concrete companies like Kilsaran.The structural engineer will specify those things usually, but often the mix designs are worked out in conjunction with the concrete companies, because they'll often be able to tell you what products you can add or take away to best make your concrete suit what you're pouring.They tend to be fairly willing to help, and most of them have plants here in Dublin (sorry, assuming you're in Dublin).If they can't give you definite answers, they'll certainly be able to point you in the correct direction. Slumps and ratios tend to be pretty standard, and the cement content they should certainly be able to help you with.Ask any questions, they have people who specialise in mix design.

Spot on, roadstone got back to me with a full design a couple of hours after I phoned them. Would've been so much easier to do have phoned them initially than p1ssing about trying to do it myself.

Cheers lads.

dan_d

In this business you learn from experience!
Best of luck with the project (and I'm a girl fyi!):D

cunnins4

It turns out I'll be making the mix in house in college, so would it be safe to use the specs given to me by roadstone? My figures are MILES off the mark on theirs (mainly because on every part of the design part it's "not specified" "no data" or "assumed" which is sending it way off).

dan_d wrote: »

(and I'm a girl fyi!):D

Sorry about that!

godtabh

cunnins4 wrote: »

It turns out I'll be making the mix in house in college, so would it be safe to use the specs given to me by roadstone? My figures are MILES off the mark on theirs (mainly because on every part of the design part it's "not specified" "no data" or "assumed" which is sending it way off).



Sorry about that!

Roadstone would have much better quality control (hopefully) so their specs would should be a lot more precise

Ask West.

cunnins4

kearnsr wrote: »

Ask West.

I did indeed, he said to go with roadstone. May have to tweak it a bit after a couple of trial mixes, but hopefully it won't take too much!