Even though the Quonset hut was bolted down, the steel arch shape hut does not really achieve its design strength until it is grouted in place. With winter coming, I was under pressure to get it done quickly before the temperature dropped and the snow storms rolled in.
It is actually possible for concrete mix additives, such as plasticizers or accelerators, to accelerate the curing reaction so it will set in colder weather, but, the SteelMaster Quonset installation manual warned that such mixtures may be corrosive. Calcium Chloride, specifically, is known to release steel corroding chloride ions and should never be used with rebar, let alone the thin 20 gage steel of the Quonset hut.
The weather was generally too cold by that point, so I had bought a couple propane heaters and decided to get started before it got any colder. But then the weather changed and the forcast was for several days with highs above 50°F and lows above freezing. I headed out to the property to take care of this job…
The Video:
The Mix:
My grout mix was a simple 2:1 ratio of sand to Portland cement. I bought the 94 lb bags of Portland cement for ~10$ each. I already had lots of nice clean sand on site (my hill is made of it), so I just used the skid steer to bring some over to where I was mixing. Creating the mix with my own sand saved me hundreds of dollars over buying pre-mixed bags of cement. The third ingredient was water… I have no access to water on the site, but I had brought a number of 5 gallon buckets full of water with me. I did not use any additives.
I have often mixed small batches of concrete in a mixing tray or wheel barrow for odd jobs around the house. My biggest manual mix had been a couple sidewalk squares. But in this case, I knew I had about ¾ of a cubic yard to mix, and I knew that I would have lots of other concrete and stucco mixing jobs, so I decided to buy a mixer. I had been keeping my eye out for one for a while and ended up getting a decent 3.5 cu. ft. ¾ horse power electric cement mixer, on sale for 40% off. The majority is metal, but the barrel is a strong thick plastic that won’t rust on me. I paid about $200 dollars, but I am sure it will be worth it. Just the time it saved me on this one project probably made it worth it to me ;^)
Once I was all setup, I used a shovel to measure out the mix and then added water until it reached the right consistency. Ideally, the concrete should be sticking well to its self, and not to the mixer. However, until it was fully mixed, I was using a small shovel or the trowel to scrape off the sides and keep everything mixing.
I used a 3 gallon bucket to carry the mixed grout to where it was needed.
With the shorter days, of November, it wasn’t long before the sun set and I was very glad to have my work lights… However, the work-lights and mixer were quite a strain on my generator and it nearly stopped a few times, leaving me momentarily in the dark.
Near the end, when I was worried that I might be a little short of concrete, I started adding some scrap rigid insulation as a volume filler. I probably should have thought to do that from the start.
This weeks focus was on preparing for Shotcrete… The basic studs and lath were up, but we needed to get all the rough electrical and rebar in place. Sherri and I had a lot of work to do.
Here is the video.
The electrical rough-in inspection must be done before the walls are closed up. Usually, that means before drywall, but for us, it means before shotcrete. In our township, electrical inspections are done only during a few specific hours each week, so we had to catch the two-hour Wednesday morning slot or Shotcrete would be delayed to the following week.
I has carefully designed the electrical layout weeks before, and then tweaked it based on Sherri’s input. Now, Sherri and I just needed to work as quickly as we could to place the boxes, run the conduit and then finally, pull the wires thru. We used Carlon ENT (smurf tube) and I had quite a hassle getting all the boxes that I needed. Next time, I will order in advance, but that is another story.
The process took longer than I expected, you can see I am working on it several days the week before. We still had work to do on this inspection day, so we came in very early and got going. We had not been finished long when the inspector arrived. He was very pleasant and actually said he appreciated that we were doing the electrical ourselves. That was a surprise because I expected that any inspector, especially one who was a professional electrician himself, would be somewhat against the idea of home owners taking on their own electrical. He made a few small suggestions for how to keep concrete out of the openings, and handed us our “approved” inspection paperwork.
Next, Sherri and I got going on Rebar. Mostly, I was cutting and Sherri was tying.
At the end of the day, my friend, Nate, arrived to check out the site. He had been up from Indiana for a conference in Ann Arbor. He reminded me that I had first told him about this idea at my dining room table nearly 6 years ago. I didn’t ask if he thought I was crazy, then or now ;^)
Well, this portion of the build is starting to seem never-ending. It is a bit frustrating because I head out to the site with expectations of what I will accomplish and then don’t seem to accomplish half of that. The time-lapse videos help, because, like a sports coach, I can review the tapes. It looks like I am working hard, so I guess the primary thing I see is that I need to reduce my velocity expectations.
Here is the video for this past Friday and Saturday:
Reviewing the tapes (at a much slower speed than the 300 to 900 times speedup that you see) also shows that I could benefit from better organization. I currently spend too much time running to get the thing I forgot to bring with me in the first place… I guess that will improve with experience. Even moving around within the site, I often need to walk a few extra feet to get the tool I just put down. I do have a tool belt, but I hate wearing it. I find it hot and unbalanced. Maybe I should start carrying a small toolbox instead? I could set it down next to me and then move the whole thing every time I move…
On Friday last week, we got a hold of our Shotcrete contractor and made a plan for one week later. We came back on Saturday and put in a long day, but still didn’t get it all done.
I am starting to see the end of my stockpiled vacation days (less than 2 weeks left) and I need to put some days in the office next week, but with the shotcrete date looming, I am going to take Wednesday thru Friday off this week. When I run out, I will need to be more creative. My schedule is pretty flexible and I could do four-tens, or shift to California time or something like that…
One of the things still not done is the electrical rough-in. I have an inspection Wednesday morning, so I will need to get out there for dawn on Wednesday to get it done. Actually, Sherri and I have been working together on it. I am running the conduit and Sherri is pulling the wires through.
I am also talking with several recycling companies to get cheap ridged insulation. It looks like I can get it for about 40% of what I would pay at Home Depot, but I am still nervous about ordering because none of the companies I am dealing with are great about communicating exactly what I will get. Online forums discussing these companies give mostly good reviews, and the prices quoted are quite ahead of my budgeted allotment, so Sherri says I should just go ahead… Maybe I will place the order tomorrow.
Even though the Quonset hut was bolted down, the steel arch shape hut does not really achieve its design strength until it is grouted in place. With winter coming, I was under pressure to get it done quickly before the temperature dropped and the snow storms rolled in.
I have often mixed small batches of concrete in a mixing tray or wheel barrow for odd jobs around the house. My biggest manual mix had been a couple sidewalk squares. But in this case, I knew I had about ¾ of a cubic yard to mix, and I knew that I would have lots of other concrete and stucco mixing jobs, so I decided to buy a mixer. I had been keeping my eye out for one for a while and ended up getting a decent 3.5 cu. ft. ¾ horse power electric cement mixer, on sale for 40% off. The majority is metal, but the barrel is a strong thick plastic that won’t rust on me. I paid about $200 dollars, but I am sure it will be worth it. Just the time it saved me on this one project probably made it worth it to me ;^)