This is a follow-up to my original concrete casting question, detailing what I am actually up to. I would appreciate any advice you can offer.
My "Pisa" block piers need caps!
The standard caps are too small. . .I would need to assemble caps out of at least seven mitered pieces, which is not the look I want. So my plan is to pour caps large enough to complete the piers. My plan is as follows:
1. Build a form. Use masonite or melamine to create a smooth top surface, and wood or rubber trim to create the beveled edges. The bevels would actually form a channel where a brick chisel will be used on the finished product to strike off the outer two inches or so, creating a broken edge to match the standard caps. The mould would include bevels on the upper side of the mould as well, aligned with the bevels on the bottom. This forms the "pinch point" where the edges will eventually be stuck off.
Should the block be reinforced? Rebar, or screen?
2. Through experimentation, arrive at a color mix that reasonably approximates the factory-made blocks. A separate color mix would be used to create the streaks of contrasting color that run through the blocks.
3. Mix the concrete. I plan to use a cement-heavy mix (formula suggestions?), and screen the pea gravel to remove aggregate larger than 1/4" or so. Larger aggregate doesn't look good when the edge is broken off. Include the coloring in the mix.
4. When the mix is ready, sprinkle the accent color over the concrete and fold it in. Repeat once or twice. Don't over-mix.
5. Treat mould with release compound (suggestions?). Pour the concrete into the mould and vibrate the mould with my rotary hammer.
6. Remove finished block from mould. Allow to harden for a week or so, then chisel off the edges. Install on piers. Celebrate.