I needed some limestone to work some cement experiments trying to replicate both the Portland cement patent, and to make slaked lime for mortar mix.
This meant I had to be able to identify limestone. Luckily since limestone is calcium carbonate, ( a base). Simple chemistry ensures that when it makes contact with acid it will fizz (which is CO2 being released) as the acid and the base attempt to counteract each other.
If you have a large weathered rock, you may get better results if you smash it into little pieces – limestone is brittle and crushes well.
Then simply drop some strong vinegar or weak muriatic (hydrochloric) acid on the rock. If it fizzles, then it is a good bet its limestone.
Just like when talking to beekeepers, beer brewers, or any of a number of simple skills – the basics of what I am about to talk about are simple, but the chemistry rapidly gets complicated – but if you just want a simple quicklime or slaked lime realize that this level of tech was well known even before the ancient romans – so it is definitely something modern man can accomplish.
First off understand that there are two types of lime quicklime and hydrated lime.
Quicklime is made by heating calcium carbonate (limestone, marble, chalk, shells, etc.) to a temperature of around 1000°C for several to “burn” or “calcimine” it.
Quicklime is a strong base so it is unstable and can be hazardous. To make it less dangerous, water is added to” slake” it. This is also known as hydrated lime. (more…)
This was the hardest part of the entire project so far – it was my first attempt at working with cement (other than using a couple bags of ready mix to set fence poles). To make matters worse, We were being filmed by a crew from Doomsday Preppers so we were on an extreme time limit (basically we had one day to do all the cement work), I only had one helper (Thanks Dad), and my mixer kept breaking.
All in all, I am pleased with the outcome, and learned a lot about what to do, what not to do, and how I would do it if I ever do it again….
What we did up to this point was to build out dome and frame in the door. Now we have to prepare for the cement.
Our intent is to cover the dome using a concept called ferro-cement (FC). In ferro-cement you don’t have to use as much cement to cover a structure because you are using more structural wire – the ideal is chicken wire every ¼ inch or stucco mesh.
In most instances of using FC workers use a thick mix of Portland cement and sand 1/3 ratio, and work against each other to press a low slump (little water) mix against the wire. (more…)
When figuring out the door I got the basic idea from my test build in my front yard, but when my Dad came to help me build the actual cement dome he brought a lifetime of construction experience that I just don’t have.
We fiddled around and came up with an idea that I am very happy with, but due to the time constraints of the film crew we did not write down any measurements, and I could not take video of it.
However, with the pictures I made on the computer and the experience you will have building the dome, I am sure you can figure it out.
Besides the dome itself, you will need one of the extra 4.3 foot struts, some plumber strap, some nails, and 2×6 boards for the door frame. (more…)