When pumpable, one-step, high-solids grouts hit the market in the late 1980s, solids content ranged from 20 percent to 30 percent. There were two-step pumpable grouts already in the market at that time and these were less than 20 percent solids.
The belief in the industry at that time was that the solids content of these one-step bentonite grouts had to contain only active solids, solids that would swell when hydrated. Bentonite industry researchers attempted every possibility they could find to raise the active solids content above 30 percent. They did not have much success.