Laboratory research on modified bentonite PT-85 for HDD mud developement.
Vol. 31, no. 1 (2014), s. 149-154, 
HDD (Horizontal Directional Drilling) is elassified as trenchless technology. Specific character of HDD causes specific parameters of drilling mud. Searching for innovated solutions is important to fulfill increasing technological requirements. The paper presents results of lab research on modified bentonite PT-85. Research of reological parametrs, mono- and multivalent ions contamination resistance and lubricity was conducted. Rheological models for tested mud were presented also. Results show possibility for industrial application of PT-85 bentonite.