Concrete Mold Flow Test: Compound Angled Mold

Having no prior experience with concrete my intention for this assignment was primarily to develop some understanding of how the material behaves when poured into a mold. That said, I created a mold with multiple compound angles, which I hoped would help to determine how well (or poorly) a relatively dense mixture of concrete would perform in terms of filling in and turning the various corners of the mold. The following photos show my mold in process:

Once the mold was complete I mixed some concrete using a roughly 2.5:1 ratio of sand to cement and added water slowly, folding the concrete until I achieved the desired consistency (which as mentioned above was relatively thick - i.e. not too soupy or watery).

As can be seen in the above photos my most immediate difficulty was the failure of the mold itself. Once the concrete had been poured the adhesive on one of the foundation pieces failed, the entire top half of the mold shifted, and concrete began seeping out. To be perfectly honest, this actually proved to be a useful event in the context of the exercise as I ultimately learned that this was not a completely catastrophic failure. Though obviously less than desirable, once I was able to get things under control the concrete was thick enough that it seeped no further and the cast came out in a state of reasonable functionality (albeit not as pretty as I would have liked). Furthermore - and with regard to the goal of this investigation - I was pleasantly surprised with the flow of the concrete within the mold. I had half expected there to be massive voids in the form, but there were none; only minimal voids in the exterior (as seen in photos), and one of no consequence in the interior (not shown). Had my mold been constructed of sturdier material, which would have allowed me to apply some kind of pressure or force other than gravity to the wet concrete, I believe this would be a non-issue.

Removing the interior section of the mold was a bit of a chore, but that was to be expected.

And here is the final object complete with dead tree. Neither aesthetics nor modularity were of primary importance to me here, even so, I am not entirely unhappy with the shape of the planter. I rather liked Rich's suggestion of a cubist green wall, and can imagine myself exploring the geometric possibilities of pre-cast concrete for horticultural purposes long after this class has finished.