Provided is a fiber material for cement reinforcement, configured such that a resin A containing an isocyanate compound as a constituent component is present inside a fiber bundled body, and a resin B containing an epoxy resin as a constituent component is present on a surface of the fiber bundled body. Further, it is preferable that the resin A contains a polyol or an epoxy compound as a constituent component in addition to the isocyanate compound, the resin B contains an acrylic-modified epoxy resin or a bisphenol-A epoxy resin as a main component, the fiber bundled body has a tensile strength of 7 cN/dtex or more, and the fiber bundled body includes 50 to 3,000 single fibers. The invention is also addressed to a concrete or mortar molded article using the above fiber material for reinforcement.

Cement slurries are prepared that comprise water, a hydraulic cement, particles of an oil-absorbent particles and non-swellable hydrophobic particles. The particles are present in an amount sufficient to alter a property of a non-aqueous drilling fluid. The cement slurry is placed in a subterranean well, whereupon the slurry contacts residual drilling fluid on casing and formation surfaces. The oil-absorbent particles and hydrophobic particles in the cement slurry may reduce the mobility of the drilling fluid, thereby improving zonal isolation.

Cement slurries are prepared that comprise water, a hydraulic cement, particles of an oil-absorbent particles and non-swellable hydrophobic particles. The particles are present in an amount sufficient to alter a property of a non-aqueous drilling fluid. The cement slurry is placed in a subterranean well, whereupon the slurry contacts residual drilling fluid on casing and formation surfaces. The oil-absorbent particles and hydrophobic particles in the cement slurry may reduce the mobility of the drilling fluid, thereby improving zonal isolation.

A panel has a gypsum matrix, in which the following additives are embedded: glass fibre in an amount greater than 1 wt % relative to the gypsum and a synthetic polymeric binder in an amount greater than 2.5 wt % relative to the gypsum. The glass fibre and synthetic polymeric binder are present in a weight ratio of at least 2 parts binder to one part fibre. The amount of sand present in the gypsum matrix lies in the range 0-0.5 wt % relative to the gypsum. The amount of cellulosic fibre present in the gypsum matrix lies in the range 0-2 wt % relative to the gypsum.

Provided is a fiber material for cement reinforcement, configured such that a resin A containing an isocyanate compound as a constituent component is present inside a fiber bundled body, and a resin B containing an epoxy resin as a constituent component is present on a surface of the fiber bundled body. Further, it is preferable that the resin A contains a polyol or an epoxy compound as a constituent component in addition to the isocyanate compound, the resin B contains an acrylic-modified epoxy resin or a bisphenol-A epoxy resin as a main component, the fiber bundled body has a tensile strength of 7 cN/dtex or more, and the fiber bundled body includes 50 to 3,000 single fibers. The invention is also addressed to a concrete or mortar molded article using the above fiber material for reinforcement.

Lipophilic fibers are effective media for cleaning non-aqueous fluids out of a subterranean wellbore. The fibers are preferably added to a drilling fluid, a spacer fluid, a chemical wash, a cement slurry or combinations thereof. Non-aqueous fluids, such as an oil-base mud or a water-in-oil emulsion mud, are attracted to the fibers as they circulate in the wellbore.

Lipophilic fibers are effective media for cleaning non-aqueous fluids out of a subterranean wellbore. The fibers are preferably added to a drilling fluid, a spacer fluid, a chemical wash, a cement slurry or combinations thereof. Non-aqueous fluids, such as an oil-base mud or a water-in-oil emulsion mud, are attracted to the fibers as they circulate in the wellbore.

An object to provide a prestressed concrete that can be widely used for general building members, in which a chemical stress induced by an expansive material and a mechanical stress induced by a continuous fiber reinforcing wire are simultaneously used together, and due to a synergistic effect of the mechanical stress and the chemical stress, the strength is increased, the reduction in weight, reduction in thickness, and suppression of cracking are achieved, and the degree of freedom in design increased. To provide a prestressed concrete characterized in that, in a concrete into which a prestress is introduced, a mechanical stress induced by a tensional material and a chemical stress induced by an expansive material for a concrete are introduced simultaneously into the concrete, the tensional material is a continuous fiber reinforcing wire, the expansive material for a concrete is contained in an amount of 5 to 30 kg/m3, and aluminum oxide contained in an amount of 0.2 to 2.0% by weight to the expansive material.

An object to provide a prestressed concrete that can be widely used for general building members, in which a chemical stress induced by an expansive material and a mechanical stress induced by a continuous fiber reinforcing wire are simultaneously used together, and due to a synergistic effect of the mechanical stress and the chemical stress, the strength is increased, the reduction in weight, reduction in thickness, and suppression of cracking are achieved, and the degree of freedom in design increased. To provide a prestressed concrete characterized in that, in a concrete into which a prestress is introduced, a mechanical stress induced by a tensional material and a chemical stress induced by an expansive material for a concrete are introduced simultaneously into the concrete, the tensional material is a continuous fiber reinforcing wire, the expansive material for a concrete is contained in an amount of 5 to 30 kg/m3, and aluminum oxide contained in an amount of 0.2 to 2.0% by weight to the expansive material.

A fiber for concrete reinforcement is provided including 85 wt. % to 98 wt. % of a polypropylene, 2 wt. % to 10 wt. % of a polycarbonate, and up to 5 wt. % of a compatibilizer, wherein the fiber has a tensile strength of at least 600 MPa and a modulus of at least 6 GPa.