![Did a cross lap joint on these two stone offcuts [4080x3072 - 2MB]](https://poal.co/static/images/s8YgVi.jpg){kind=link}
In the picture it looks so much like it was made with wooden 4x4s and a can of Rustoleum Faux Granite spray paint! I'm NOT shitting on it, stone work has to be incredibly challenging especially when working with small geometry granite but with the length and heavy weight (lever arm torque) stressing at the cuts.
I see an opportunity to benefit from your experience here...
I've got 2 stone pillars about 5ft tall at the entrance of my subdivision road. They were made from fieldstone (granite) and have a 3ft square cross section. My Dad, his crew and I built them roughly 50 years ago. Dad made the top caps for the pillars by building wooden forms and filling them with cement, curing, removing the forms. They are fancier than simple slabs, he used wood trim in the forms to provide added detail. My problem is that the caps are failing after 50 years. One cap has a ~10" hole in the center, the other was found broken into a dozen pieces last year. It took 4 of us to place each cap back in the day, they were very heavy. My concern is rain/water entering the top of the pillar, refreezing and cracking up the cement holding the stones together. They must have caps to protect the pillars.
My choices, as I see it, are to build new forms and make new caps like my father did, or contract a stone mason to cut real granite caps out for me. The caps are roughly 3' 6" on each side and the cement versions were maybe ~3" thick (+/-3" overhang).
What would you recommend? If I make wooden forms, which cement would offer the most strength and durability? Should I consider embedded wire screen to ad strength and to keep them intact if they should ever crack? There wont be anyone around in another 50 years to make new forms and fix this if it happens again. I was thinking high pressure fiberglas reinforced cement might last a really long time.
Or I can pay all the money and have them made from granite by a pro. I think I'd rather follow the family tradition and make them myself like my Dad did, but use the toughest cement I can find. What would you recommend in my situation? Plus, I'll have to find someone with a crew or equipment to place them on the pillars, I'm retired and have no crew.
Thanks. It's bluestone. Honestly you're fine with whatever bag of premix you like. It's all about proper curing. Pour it when nighttime temps stay above 45, keep it tarped and mist it a few times a day for a week or two. You could add some fiber reinforcement (nylon fibers) and some wire mesh if you want, but I don't think it's necessary. Vibrate your form with an empty sawzall to get some bubbles out. To add a little pitch to the top build the forms higher and notch the end of a 2x4 so that the notch end sits at your 3" mark and the other end is on top of the form on the opposite side. Use that to screed the cap into a slight pyramid.
The tarp is to keep rain out or moisture in during the curing process? I'd be building the forms and filling them with cement in my shop in the spring, so temps and rain won't be an issue.
I gather that a longer curing period while maintaining an abundance of moisture is key to forming the strongest cement. This might be where my Dad's caps failed, I doubt he wet them down during the curing period. I'm pretty sure he vibrated the bubbles out, probably just by using his hammer to vibrate the forms back in the mid-1970s.
I think I'd go whole hog on the caps. Steel wire reinforcement + nylon fibers + vibration + slow wet cure. I'll only get one chance to do it right ... I'm running out of years to keep an eye on them.
Yes, the tarps keep moisture in. Concrete is fully cured in 30-40 days. Giving the caps some pitch at the top is also important. I'm betting that big hole is from water standing on top, popping out a bit in the freeze and growing from there. You don't need much, maybe 1/4".
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