New Skills and New Tasks: Concrete Finishing and Welding
As I mentioned in my introductory post about my Americorps service with Santa Fe Habitat for Humanity, one of the things that interested me about working with this particular affiliate was the opportunity to learn new tasks and gain new skills. Concrete work and welding in particular are both things that I’ve not seen done elsewhere and the latter is something I’ve had interest in learning more about for quite some time. I am under no illusion that we do any more than the basic forms of both these tasks at Santa Fe Habitat, but just being exposed to the steps involved and getting the chance to do them has been pretty great, and gives me a foundation to hopefully learn more in the future.
Concrete work at Santa Fe includes things like filling fence post holes, filling block for the foundation of the adobe walls, and capping the earthen walls after they’re built, but what I am referring to in this post is the pouring of sidewalks, walkways, and porches for which we order a truck as opposed to hand-mixing individual bags of Quikrete. Also, to be clear, we do not pour our own slabs; that’s a whole different art. Dealing with a larger volume of concrete then individual bags is unique in and of itself but it’s the finishing techniques that make this a new task for me.
First, before the truck arrives, we have a bit of prep work in digging out, compacting, and leveling our subbase to the correct depth. With sidewalks in particular we use the builders level to make sure our pour is seamless with the existing sidewalks and bridges any differences in height. This work usually happens concurrently with the other initial step in the process – creating forms. The most basic function of creating forms is to define the space in which you want to concrete to be contained, but what is more tricky is making sure your form is at the correct height, level, and squared – to existing concrete in the case of sidewalks or to the slab in the case of porches. You also want to incorporate a slight slope away from structures to aid in water runoff. Thus, preparing the subbase and putting in forms can be, depending on the grade of the land, a bit time-consuming. Lastly, we lay re-bar and/or re-mesh to provide stabilization and add strength to the concrete and put in any expansion joints that provide a buffer between the concrete and things like the adobe walls.
The day of the pour we use shovels and rakes to even out the material in the form as it comes out of the truck, pulling up any re-mesh to make sure it is embedded in the concrete and not sitting on the ground. Finishing concrete is largely a process of flattening, compacting, and bringing the non-gravel part of the mixture to the surface so that it may be jointed and textured. Screeding is the first step in which a flat surface is dragged across the pour to even it out (we use a 2×4) and skim off any excess. This also helps to fill gaps and compact the mixture. Immediately following this we begin “floating” the concrete by running flat magnesium tools across it. Bull floating, in which a large float on an extension pole is run across the surface multiple times, begins forcing the gravel down and noticeably smoothing the surface. After this step hand floats (sometimes referred to as trowels) help further smooth the surface and bring the water or “cream” to the surface while forcing down the gravel. This involves light, sweeping strokes and requires a steady hand. Depending on the weather and the composition of the mixture this step can be very quick or take quite a while. Once a finished surface has been achieved, we can proceed with creating rounded edges by running an edging tool lightly along the inside of the form and also cutting joints (e.g. the lines on sidewalks) into the concrete. Lastly, when the concrete has reached a desired firmness, we run a fine broom across it to create some traction and help water to drain off.
Welding, as I mentioned, is something I’ve had my eye on for quite some time. Lucky for me, Santa Fe Habitat does a fair amount of it since the dominant architectural style in Santa Fe includes coyote fences which consist of young trees (called latillas) wired to a welded framework. For these fences we sink 2” thick pipe at least every 10 feet and have two 1 ½’ rails running horizontal. We also have 2 gates on average per house to provide access from the front and back. This necessitates a good amount of welding per home.
I began my overall welding experience by using the abrasive cut off saw and grinder to fit the pipes, learning the hard way that accuracy in calculating the angles of the cuts that are necessary to achieve the correct throat depth of the pipe. Since I was/am brand new to metal work my cuts were not very good and I ended up with too much space between most of my pipes and a poor fit in general which made my first welds extra challenging. Even without dealing with the need for multiple passes however I struggled mightily on my first day despite Daniel’s best efforts to teach me; let’s just say those welds aren’t the best looking ones on the fence.
My second and third attempts at welding were in making the 2 gates, those welds made difficult by my inability to get good enough cuts on my first few tries that would let the gate hang in plane. To force it to be in plane (i.e., lay flat) I ended up with more space at my joins than I would have liked. But by this time I was more consistently laying down a decent bead and getting more comfortable with welding in general. During those 2 days I also began getting some good experience in how to fix the welder when it would stop feeding wire. I must confess however that I burned myself a bunch of times and took a really long time to produce a barely-passable product. I concluded during those 2 days that a) welding does not come naturally to me, b) good welding requires practice, c) burning myself escalates my frustration levels, and d) I had to dig deep to embrace my failures. But I ended up with 2 usable gate frames so I count this as a win.
Over the past week I welded another 2 days, attaching the horizontal pipes in place on the back fence at Carolina’s house, and putting in her 2 gates. Both these days I spent time teaching other people and then supervising as they practiced. I have become comfortable over the past couple years sharing what I know and teaching skills to others on Habitat sites – even one I don’t have much experience with – but I admit to feeling a little unprepared to teach a task I still feel very unskilled at. At the end of the day however both Callahan and volunteer Jebb picked it up quickly and we didn’t run into any unsolvable issues or make any serious mistakes, so despite not feeling prepared I must admit that it all turned out well enough.