Yeah I am contemplating putting some REO into the rock by drilling in and chemical anchoring. Its all good though. Some more planning first though.
Use Rockite, that is what it is designed for. Bunnings have it. I used it for rocket nozzles, it is basically nonexpanding but sets like rock and secures them extremely well. Cures in about 30 mins for hard but goes absolutely solid in 24 hrs.
It is used in the building industry to secure railings and the like into concrete floors and surfaces.
Went down to the house today and formed up the pier support. Steel reo rod of 10mm with some mesh over the top. Also you can see the power conduit with guide rope.
Concrete this weekend. Another week or two and I will go the outer concrete for the rest of the obs to sit on.
Had a visit from my old mate Conacrete today. Pier support poured and finished. Dimensions are 1400 x 1200 x 900 (tapering from the top down the bottom with a dimension of 600 x 600); approximately around 0.85 cubic meters. I think that is about 2.1 tonnes. Certainly more than enough weight to hold the scope in position.
Maybe end of next week I will pour the outside section of concrete to hold the dome. Images to follow.
Now that the pier support has been stripped of its formwork, I picked up a half a tonne of compaction sand to level off the site to allow for concrete to be poured next weekend, which will surround the pier support. Watered in and levelled off. The site will need to be quite compacted before I pour concrete to ensure it remains stable. This stuff sets very hard after a bit of rain, which we are expecting tomorrow.
Today I went down to the house and formed up the outer concrete ring. Concrete is ordered for Saturday and the weather looks good. For those interested I used 6mm plywood for the form and 75mm gal mess for the reinforcement. I cut the plywood to 100mm thick and the reo stools are 45mm high. Concrete will be 25mpa with structural aggregate. Getting exciting now. Not long before the dome will be installed.
In the first image you can see the pins placed to hold the form and I have adhered the expansion joint foam to the side of the pier support.
In the second image you can see the completed form. I had to scribe around the rocks on the other side and black form plastic to prevent moisture coming up through the concrete.
Don't mind the rocks, we have been having some windy days of late (normal for the time of year) and those are just there to hold down the mesh until pour day.
Your observatory will be operational before you know it
Incidentally the pier support pad looks quite large, was there a particular reason for this?
Mike
Yes thought you might see some familiarity there Mike. The diameter is 3 meters though.
The whole process started in March this year when I decide to buy the dome. Building the backend of the scope has taken about 7 weeks now and is about to have a major upgrade from what I lovingly called the Battle Tank. I will you guessing on that.
The pier support is the same as the one in the roll off roof obs seen in the background. The larger the pier support the less likely there will be any movement from the weight of any large mass such as a large OTA swinging and causing a moment of inertia. All this obs has been planned with a much larger telescope in mind down the track. I don't want to leave anything to chance. The imaging train and the pier support structure are part of that plan. The pier will also have a large diameter too to prevent deflection. Part of my plan to collect mega data. For now it will be the RC12, but in time it will be something else. I will give you a guess though. The pier will be around 600mm long at most.
Hope your concrete turned out well Paul. Just sprayed mine to add a little moisture to it. A little hot out there today.... Great day for curing concrete.
It was ok Andrew, but I ordered 25MPA and I think I got 35MPA. The mix went off in 45 minutes. I just got it screeded off and it was getting hard. That made it hard to trowel it off. I ended up with small holes of around 5mm in the topping here and there. I can sort it later with flowcrete, but the mix came from Port Elliot and it was a little dry on arrival. It will be hard as a rock now. It should have had a bit more water in it to account for the warmer weather.
Anyway another image for you guys to peruse. Next step installing the dome next weekend, with the help from a mate or two.
Good Job Paul. Bad luck about the quick setting though. I was lucky mine was quite wet, but also only had 2km from the Concrete place to here, so not that much of a drive. Cant wait to see the dome on it.
Good luck with the concrete.
