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Abstract

Magnesium oxide is included in a bentonite clay anti-friction composition in an amount of 0.025-0.25% based on the dry weight of the clay to substantially improve the efficiency of underground cable or pipe installation. The anti-friction composition is applied between an outer surface of the cable or pipe and tunnel walls to substantially and unexpectedly reduce the amount of force, e.g., hydraulic pressure, necessary to push or pull the cable or pipe into its intended location within the tunnel. The composition includes a water-swellable colloidal smectite clay, such as bentonite, and magnesium oxide in an amount of 0.025-0.25% based on the dry weight of the clay. In another embodiment, the composition also includes a polymeric fluid loss reduction agent, such as carboxymethyl cellulose to decrease the amount of the clay composition absorbed into the tunnel walls. Soil is extracted underground to form a tunnel and the cable or pipe is forced by a hydaulic jack, into the tunnel. The tunnel walls surrounding the cable or pipe are contacted with the composition comprising a water-swellable colloidal smectite clay and magnesium oxide in an amount of 0.025-0.25% based on the dry weight of the clay, while forcing the cable or pipe into the tunnel.

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First Claim