When I got my analysis back for the SW AR marl (https://glazy.org/materials/96006) it got me thinking. If this material works why not limestone? The marl has less loi but only about 5%. Limestone would have some advantages for me as it’s non-plastic (the marl has some plasticity) and I need to reduce plasticity and drying shrinkage. Plus, the limestone quarry is only about 10 miles from me and I can get dust extremely cheap. The rock is $10/ton and the dust slightly higher. Just have to sieve it. This batch I sieved down to 100 microns. So about 140 mesh. This analysis for the limestone is from an old geology paper https://glazy.org/materials/26745
I mixed up tests yesterday. 10% of the added marl resulted in 1.9% porosity at cone 6. I mixed tests of 5,8,10 for the limestone. The limestone has more calcium less silica and alumina. I’m going of an old analysis from the 1920’s for the limestone but it’s the same vein of limestone still being mined. It’s Goodland Limestone and according to the old analysis very low magnesium and 1.3% iron.
I mixed these up with my sand light colored clay which is the same clay I tested with the marl. The test bars will be fired to cone 6.
