ON mODIFIeD BeNTONITe PT-85

Horizontal Directional Drilling is a trenchless method used for installation of pipe-lines, air-pressured and gravitational ducts as well as cable installation � This drilling method is utilized on terrains with roads, highways, railway tracks, canals, rivers, and highly urbanized areas, where direct pit under the ground is impossible � Trenchless tech-nologies such as HDD have more advantages than the traditional methods � Not only do they shorten time necessary for dig-up, but also the pipelines used during drilling can be placed in any desired position under any territorial barrier � In addition, HDD does not disturb public transportation and most importantly, does not devastate the environment, what makes it the commonly used technology in the construction industry. Drilling muds that are used for HDD have to possess certain rheological qualities that will facilitate the process � Because of the relatively short distance for cuttings to fall, drill-ing fluids should have higher yield point and be resistant to structural pressure. Rheological parametres of drillig mud have fundamental meaning for drilling proces � Technical and eco-nomic effects highly depend on these properties � Basic factor conditioning proper selection of drilling mud is adjustment of suitable rheological model to a given mud. Particularly it’s most important in horizontal drillings – as in HDD technology� Currently used mud are drawn up from bentonite base that is modified with poly-mers. These modifications are often made by using the hydrolyzed polyacrylamide