All recommendations are welcome. In particular how to vibrate a two part mold without it breaking apart. I did not weigh the mix and water, but i suspect i used too much water. Also added about 2% plasticizer.
this post was submitted on 03 Aug 2025
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The vibration required is pretty serious. If you look into how they make concrete bricks you need a lot of force and control for the frequency to make it effective.
https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?referer=&httpsredir=1&article=1024&context=mesp
I used this as a basis designing a table to vibrate epoxy-concrete molds for machine tools. You'd want the dildo attached to a hammer drill style vibrator for small scale application. https://i.imgur.com/RcIcqk1.jpeg I used a steel plate here, 2hp Craigslist motor, bicycle tubes, rubber and wood. My plan was for larger molds..
That, and the aggregate ratio also being the two critical parameters. Edit: the whole requirement is also dependent on your needs. You can change a lot if you don't need serious strength to better target surface finish.
I forgot i had this, will try it though the frequency is probably lower than what you suggest.