Dome construction

This weekend was tough. Lots of concrete mixing, moving and experimental methods of applying it to the dome form.

AJ and I did some testing with the concrete pump. It turns out that it does not work well with the relatively rocky mix of concrete that we put together. In fact, we managed to plug the hose and had to sacrifice the entire batch of concrete to get it unplugged before it set up. Not everything goes as planned I guess.

We set an appointment for Saturday to try to cover the dome with cement. With the pump out of the picture because of the rocks, we had to apply it by hand. We figured on a few hours to get the dome covered... Turns out that it took us most of the day just to get about 1/2 of the dome covered. The cement was not cooperating and ended up sliding off the dome and onto the ground all around the base. I wanted to give up and try something else, but despite the large amount of concrete piling up around the base of the dome on the ground, we did manage to get most of it on the form.

We let the concrete set up for a couple of hours over lunch and then went back to work trying to add more. It was pretty frustrating. Some of the concrete seemed to crumble away as we tried to add more to it. Part of the problem was that we tried mixing up some thicker mixes to see if it would stick better which ended up just making the mix thicker and harder to spread.

By the end of Saturday afternoon we had 99% of the dome covered with at least some concrete. The idea was to come back in the morning and try shooting it on in a thin layer.

Sunday morning we started off by sifting the rock through a screen to remove everything smaller than 1/4 inch. That helped to make a mix that went on smoother and easier than the Saturday. Within 3 hours we had a pretty good coat of cement over the entire dome. There were still some patches that were too thin, but the dome looked more uniform and the rough texture of the sprayed concrete actually covered up a lot of the rough work from the day before.

After lunch, AJ deflated the form and we removed it from the inside. I thought that we were done for the day, but AJ decided that we should do a coat of cement on the inside too. So, we went back to work. It took a couple of hours to coat the inside of the dome. It's a bit rough both inside and out, but it feels surprisingly cozy and roomy inside. From the outside it looks rather small, but from the inside it seems larger. I don't have any pictures of the inside after the coat of cement. I'll get some later tonight or tomorrow if the weather holds out...