After 14yrs, the black plastic bed edging around my landscape beds was deteriorating and needed to be replaced. I decided on concrete curbing for a better mowing & trimming edge and something that provided a better barrier between the rock/mulch and the grass. I had about 1200 feet of edging to replace. After finding out that professional curbers charge a minimum $6 per foot ($7200 project!), I decided to purchase an Electric curbing machine from Northern Tool and try the project myself. I was able to figure out how to do it using Google searches, but mostly from watching YouTube videos, primarily videos from Borderline USA (they have great videos).
I'd have to say this is one of the more challenging home projects I have done. It's also very physically demanding, at least on the guy running the mortar mixer (sand is heavy). You can do it with 2 people, but 3 is much more efficient (A mixer guy, a wheel barrow guy, and someone to run the machine and finishing) because you can keep the mixer running continuously. A 4th person could be a finisher, and then you'd really rock and roll.
List of Videos in my series
DIY Curbing - Final Result
DIY Curbing - Part 1 Mixing Cement
DIY Curbing - Part 2 (1st Section)
DIY Curbing - Part 3 (2nd Section)
DIY Curbing - Part 4 (3rd Section)
My biggest problem (after figuring out the mix) was small 'blow-outs' like in Parts 3 & 4. It seemed to happen when I let the front of the mold get too high (the rear wheels dropped) and the mix would push out the front. This happened when the the back of the machine dropped like when starting downhill (even a little).
I did have to do a fair amount of troweling after extrusion. This is probably due to my inexperience keeping the correct amount of back pressure on the machine and keeping the wheels at the right height (which keeps the mold parallel to the ground), and maybe my mix was a little dry.
The Klutch Curbing machine worked fine. We metered in the concrete with a shovel and it only jammed once or twice (an occasional rock got into the sand). I just turned off the power, opened the motor access panel and rotated the belt backwards a little and restarted the machine and all was well. Clearly the biggest pain was dragging around 200ft of #12 extension cord, but the electric machine was way cheaper than a gas unit.
Our mix recipe was:
4 5-gal buckets of Mason sand
1 47# bag of Portland cement
1/4c cup (3oz by weight) of 'curb Gravy'
2# of Solomon #417 Red
Water until the mix was right.
The goal is to get a mix that is wet enough but does not slump (it holds its shape). When checking if the mix was wet enough, Tom made a snowball and bounced it in his hand to see if it held together (looking for cracks). He was looking at his glove to see how much moisture was on his glove. After doing many mixes he was able to tell how wet it was based on that and how it bounced in his hand. We did about 20 mixes and he was very consistent all day long. Check out Borderlines mixing video:
The amount of sand determines a few things - the strength of the mix (too much sand and the concrete gets weaker). The amount of sand also determines the linear feet of curb you get per mix. We were getting about 19-20ft per mix using the Klutch slant mold. The recipe in the Klutch manual was 5-buckets of sand to 1-part cement, which would really make a lot of curb (like 25ft), but I didn't find any other recipes using that much sand, so we went with a 4-bucket mix. The borderline guy points out in his video that this is slightly more than a 4:1 mix.
I didn't show spraying Mineral spirits on the release powder or sealing the curb. These Borderline videos cover that:
Curbing Machine - Klutch #49404 (I paid $812 after sale and flyer coupons)
From Bordeline
Curb Gravy water reducer 10#
Pink Troweling Lube 1gal
Aussie Slate Roller Stamp
Random Rock Roller Stamp
The borderline rollers were 5-1/2in wide, just a little narrow for the Klutch slant mold and my novice hand. A 6in roller would have worked better for me.
From My Local Concrete supply Company
Solomon Colors #417 (used ~2# per mix)
Gray powder release
A professional 3.5gal Chapin sprayer with a 0.2gpm spray tip
1/8 inch touch up roller
AS-1 25% solids acrylic sealer.
Things I rented
Sod Cutter from my local Coop (I purchased a 9in blade for it)
Mortar Mixer from a local contractor supply ($135/week)
From my landscape supplier
Mason Sand (finer than torpedo sand)
Miscellaneous
5-gal buckets, 7-inch roller and frame, 10Qt bucket, 1qt container, 2-wheel wheel barrow
After buying all this junk (equipment & supplies), I spent about $2500
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