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Re: Partial cement replacement

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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

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> 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
> > >
> 
>