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Playing with Fibre and Breaking in the New Mixer

We had a good turn out to our first pour with 1 new member from first year coming to help.  Today’s goal was to get a feel for the mix and the forms and experiment with workability.

Mix 1:
For our first mix we tried the lowest water content to cement ratio we thought possible (0.3).

We choose pea gravel as our core aggregate as the mix needs to fill in between the mould and the core in the final design.

LtoR: Sudip, Fraser, Max, Richard(adding water),Nathan, FraserLtoR: Sudip, Fraser, Max, Richard(adding water),Nathan, Fraser

We ended up needing quite a bit more water than we originally thought.

We used forms from a previous year (with a bit of extra duct tape) to see how well they worked and poured 5 cylinders of each mix.

LtoR: Nathan, Fraser (preparing cylinders), Sudip, Max and RichardLtoR: Nathan, Fraser (preparing cylinders), Sudip, Max and Richard

Mix 2:
For our next mix we increased the water to cement ratio and tried adding fibre. Sudip, our Faculty Sponsor, brought us four types of fibre to experiment with. We decided to use STRUX 90/40 from Grace Concrete,the longest of the fibres because we thought they might be the one to decrease the workability most/ get clumped in the mixer. For many of us it was our first time
using fibre in a mix.

R:Filling Cylinders after the Slump TestFilling Cylinders after the Slump Test

The fibre only clumped very slightly. It definitely decreased workability, but with the increased water content workability wasn’t an issue.! !! Friday,

January 8th, 2016: Stripping
At lunch on friday we came in to strip the cylinders and the two bowling balls. It was very tricky getting the forms off the bowling balls. We ended up cutting them off and discovering some of the masking tape lining the forms had cured into our bowling ball.

Our Plan Next:
Our first pour in the the lab helped us get a feel for workability and working with fibres. We discovered 1) using less fine aggregate helped a lot with workability when using such a small coarse aggregate 2) our forms can’t have tape on the inside and need an easy method of removal such as a hole for air pressure 3) we need to come up with methods to make our mix lighter.

We’re planning to meet on Monday and have a second lab day later in the week.

It’s exciting to plan design and experiment with a project outside of class. We really appreciate your support!