Tuesday 23 October 2012

Mixing Cement

Cement is an incredible chemical soup that we always take for granted.
It's grey and usually lifeless.
It supports us everywhere, yet is ubiquitously known for being drab, boring, and carries the stigma of cold urban infrastructure.
There is a calculated reason that it has been restricted in Gaza.
Cement builds structure like no other material.

A little tip if you live in snow country...or rain country too.
Never build doorways or other entrances where a roof sheds snow or water.
So when building our schoolhouse, the entrance needed to be placed at the gable end of the building.
One step further; we used the woodshed as the entrance to fend of the elements before reaching the door.

Today's project needed materials, but all of them were leftovers.
Some cement, pressure treated lumber, off-cuts of styrofoam insulation, steel re-bar, and a piece of plywood.
All of these materials are based from toxic chemicals.
I suffer through their use, but am at a loss for natural alternatives.
Cedar and stone would suffice had I not the waste from other jobs.
But there is no equivalent in nature for concrete...
...other than hot lava!
(Which, by the way, I do not possess the appropriate safety gear for.)

The ramp to the door is a form made of a sheet of plywood and a frame.
The wood only holds the cement until it dries.
I used steel bars to both strengthen the cement mix and join the ramp to the building.
The bars go right through the wood into the end joist.
The concrete is heavy and needs as much support as possible.
Once it cures, it provides much of it's own support.

Cement mixing instructions are on the bag.
Ready-mix only needs water, but they skimp on the important parts.
Mix your own if you can.
Get a cement truck if it's over a cubic yard.
Many people rent a power float to finish the concrete.
I use a piece of wood on a stick.
Keep it simple.
Look up instructions on floating concrete online.
They say to bring the 'cream to the top' which is a euphemism for drawing the cement paste to the surface, but if you get carried away, the surface will flake off after it dries.
Also, working the surface too much allows the mix to settle out so the stone will sink to the bottom.
It's better to a have the aggregate evenly distributed.

Chicken tracks look great if you have no OCD.
Myself, I had to wait until chicken bedtime so I could repair the surface.
When the weather is dry and warm, you won't have much time.
The damp and cool air gave me a second chance to make things right.
Yes, I know.
The chicken tracks look pretty cool.
But they also kicked dirt on the walkway, and pooped on it too.
It needed to be smoothed out again.

You can probably tell that Kira thinks it's funny when I indulge myself.
Perhaps you can see your reflection in the carefully smoothed concrete.
Yes it's smooth.
So smooth.
I'm sorry...
..what were we talking about?


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