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Re: Partial cement replacement

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INDICATIVE MIX FOR GGBFS PARTIAL CEMENT REPLACEMENT

I am not able to publish the 60% replacement GGBFS cement replacement
mix for the Wellington Sewage Scheme - because of the proprietary
interest of other members of the Design and Build Consortium.

However the following mix proposed for a more recent project
may serve as a guide.


     GGBFS               228 kg/cubic metre
     Portland Cement     152 kg/cubic metre
     Coarse Aggregate   1150 kg/cubic metre
     Sand                700 kg/cubic metre
     Water reducer/Super Plasticiser     to suit from trial mixes

ROY G TAYLOR P Eng
Director
CONCRETE TANK CONSULTANTS (INTERNATIONAL) Ltd




Kho Poh Teck wrote:
> 
> Thanks for all your valuable information. In our work here, the Max w/c
> ratio specified was 0.4 and there is a bit of a problem getting the correct
> slump. I don't really like to increase the admixture dosage than is
> neccessary without compromising the strength requirements.
> 
> Frankly speaking I'm not a good chef but would be nice if you have some
> recipe for a correct pump mix. Could you recall your mix design in your
> sewage plant project in NZ, Dr Taylor?
> 
> KHO
> CEng MIStructE
> 
> ----------
> > From: RG TAYLOR <abuild(--nospam--at)xtra.co.nz>
> > To: seaint(--nospam--at)seaint.org
> > Subject: Re: Partial cement replacement
> > Date: Wednesday, October 14, 1998 08:11
> >
> > RG TAYLOR wrote:
> > >
> > > Partial Cement Replacement
> > >
> > > We have had experience with GGBFS (slag) replacement in $NZ160 million
> (Approx $US80m) sewage plant
> > > in Wellington.  The tanks had a total of 10,000m3 of concrete.  The
> concrete for the tanks was 60%
> > > GGBF replacement and 40% OPC (Ordinary Portland Cement).  There would
> be some similarities to other
> > > slag replacement applications such as massive pile caps, although our
> thickest wall was about 1m thick.
> > >
> > > While the sewage project was very successful (See aerial picture on our
> website
> > > http://www.abuild.co.nz/concrete/tank.html) and we have high
> expectations of excellent concrete
> > > durability  there were a number of practical design issues withh the
> concrete mix inter alia:
> > >
> > > 1)  Workability of the 60/40% blend of concrete - significant amounts
> of superplastiser had to be
> > >     used.
> > > 2)  Special design was required for a pump mix and required some trial
> and error.
> > > 3)  In design for continuous pours of wall up to 30 - 40m needed
> investigation as to whether the
> > >     design crack width of 0.15mm could be achieved with different
> material and hardening behaviour
> > >     i.e. different from OPC in micro behaviour. In practice it worked
> out particularly well.
> > > 4)  Care is required in taking formwork off early because of slower
> hardening rate.
> > >
> > > Roy G Taylor  P Eng
> > > Director
> > >
> > > Concrete Tank Consultants (International) Ltd
> > > Phone   +64 4 478 3424
> > > Fax     +64 4 478 3424
> > > Email   abuild(--nospam--at)xtra.co.nz
> > >
> > > Kho Poh Teck wrote:
> > > >
> > > > Is anyone familar with concrete mixes with GGBFS (Slag)? What would
> be the
> > > > best proportion of cement to slag with a max w/c ratio of 0.4 and a
> slump
> > > > of 125mm? Can anyone be kind enough to let me know for Grade 50 or
> Grade
> > > > 40. The concrete is intended for massive pilecaps.
> > > >
> > > > KHO
> > > >
> >
> >
>