Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Partial cement replacement

[Subject Prev][Subject Next][Thread Prev][Thread Next]
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
> >