I finally have been able to make a hard, durable brick. I was lacking a flux that would work in the short firing time frames I am forced to use. Salt and lime didn't work fast enough. But ground up glass dust did. What takes pure clay several days firing to do, I now can do in 1 day!
Old scrap glass from bottles, windows, and television picture tubes is smashed down in my mixer with heavy round stones.
Old scrap glass from bottles, windows, and television picture tubes is smashed down in my mixer with heavy round stones.
before adding it to the clay to press out bricks.
The three bricks to the left are regular clay bodies for a control. The forth, sixth, and seventh are 50/50 red field clay and glass. The fifth brick is 50/50 grey streambed clay and glass.
The controls were not vitrified and crumbled easily. The red clay/ glass bricks were solid and passed water absorbtion testing averaging 11% and maintained full strength. The grey streambed clay / glass brick had absorbtion at 22% and split minutes after submersion in a bucket of water.
I attribute the failure of the streambed clay brick to the high level of lime pebbles in the clay mix it was made of. The lime swells as it absorbs water causing fractures in the clay body of the brick. I will work on removing the lime pebbles for the next tests as I really liked the near white look of that brick and would want some of them to hold up for me.