A method of cementing a geothermal wellbore includes pumping a first volume of cement slurry down a wellbore. The first volume of cement slurry has a first water to cement ratio. A second volume of cement slurry is pumped down the wellbore. The second volume of cement slurry has a second water to cement ratio that is less than the first water to cement ratio. The first volume of cement slurry hardens at a vertical portion of the wellbore, and the second volume of cement slurry hardens at a horizontal portion of the wellbore.

In one embodiment, a building material derived from a geopolymer formulation comprises sand, ground granulated blast furnace slag (GGBFS), fly ash, sodium tetraborate, boric acid, zeolite, sodium caseinate, and SC-9. Optionally, the formulation also comprises additional constituents like sodium metasilicate, sodium hydroxide, magnesium oxide, hemp, basalt fibers, aggregates, and fillers. The building materials have high compressive strength, flexural strength, tensile strength, impact resistance, and thermal resistance.

A thermally conductive silicone composition comprises: (A) an organopolysiloxane having at least one alkenyl group with 2 to 12 carbon atoms per molecule and having a viscosity at 25 C. of from 10 to 10,000 mPa.Math.s; (B) a hydrophobic fumed silica; (C) at least one thermally conductive filler; and (D) at least one polyether selected from a group consisting of (D.sub.1) a polytetramethylene ether glycol. (D.sub.2) an alcohol initiated ethylene oxide and propylene oxide copolymer, and (D.sub.3) a polyether-modified organopolysiloxane. The composition exhibits good shape-holding property and high thermal conductivity despite good handleability and dispensability.