Testing and Conclusions

Testing with water

We used two watering cans to imitate the effects of rain, we continuously filled them up and poured them onto the dome over five minutes and recorded the results via video.

As the video shows, the mud cladding was not very waterproof to say the least....

Why did the cladding not resist water?

The mud cakes, although smoothed at the joints, shrunk and receded from each other to create cracks and holes in the cladding (we should have foreseen this as it was extremely obvious to us after it had happened).  We believe that the straw needed to be cut much more finely as to integrate with the mixture more thoroughly. In hindsight we probably wouldn’t include the straw unless we were doing two layers of cladding, as it is purely an insulative measure. The sand that we mixed with the clay and straw was granitic sand....in other words, the wrong sand. The sand wasn’t fine enough and therefore made the mixture dry inconsistently and hard to apply.

The mud isn’t dry!!!

Over the few days that we allowed the mud to dry it had rained, but never fear, it was covered by a big farm shed..... Little did we know that the shed leaked right where the dome was situated and therefore the mud cladding didn’t dry fully, although it was still a lot drier than when applied.

How did we try to rectify the situation?

Upon realisation that the mud had receded and shrunk during its interrupted drying period we decided to make a mixture that consisted only of clay and water, apply it to the cracks and holes and attempt to dry it under high heat. This would, in theory, stick to the structure more successfully than the previous mixture and was able to be easily poured into cracks to fill them. This worked to an extent but again, we underestimated the drying time and some of it washed away with the application of water.

If we had our time again

If we were to change a few major things about this assignment they would be:

-        - The mixing and application of the clay/mud cladding. We would use finer sand, like the sand used with cement and we would (if using straw at all) chop or blend the straw into a much finer mix.

-      - The mixture would be applied to the outside of the inside skin of chicken wire and then the outer layer of chicken wire added, followed by another layer of mud on top of that, this would create a much stronger skin and would be much more waterproof.

-         - The entire dome, once the two layers of mud cladding had set, would be covered with a thinner (with the         addition of more water), more cement-like mixture of clay sand and water, omitting the straw.

-        - We would have made a ridge (similar to the one around the window opening) around the edge of the cladding at the halfway mark where we stopped cladding to show the structure beneath and create a cut away effect, so that the water did not drip over the edge and instead ran down the sides and onto the ground.

In conclusion, we believe the structure held up beautifully, it was of sound design and assembly and it looked great, it lent itself to a number of different claddings and was lightweight, enabling it to be moved around with ease once constructed. The cladding was a bit of a failure but the results needed to construct a much sounder model were obtained and recorded for later use or use by other people looking to make a mud clad geo-dome. All in all it was a success in that we discovered why and how things did and didn’t work. 

Archive photos for the day