A method of sealing propagating cracks in a sensor-laden cement sheath comprising the steps of monitoring an electrical resistivity of the sensor-laden cement sheath to produce a measured value, wherein the sensor-laden cement sheath comprises a conductive sensor, an on-demand expanding agent, and a cement, activating a heat source when the measured value of the electrical resistivity is greater than an activation threshold, increasing a temperature of the sensor-laden cement sheath with the heat source to an activation temperature, wherein the activation temperature is operable to initiate a reaction between the on-demand expanding agent and water, wherein the activation temperature is greater than a formation temperature, reacting the on-demand expanding agent with water to produce a swelled agent, wherein the swelled agent occupies a greater volume than the on-demand expanding agent, and sealing the propagating cracks in the sensor-laden cement sheath with the swelled agent.

A method can include conveying a dispensing tool through a wellbore, the dispensing tool including an enclosure containing plugging devices, and then opening the enclosure by cutting a material of the enclosure, thereby releasing the plugging devices from the enclosure into the wellbore at a downhole location. A dispensing tool can include a container having an enclosure therein, the enclosure including a flexible material that contains the plugging devices, and an end of the enclosure being secured to a member displaceable by an actuator. The enclosure material is cut in response to displacement of the member by the actuator. A plugging device can include at least one body configured to engage an opening in the well and block fluid flow through the opening, and multiple fibers including staple fibers or filaments formed into yarn.

A method can include conveying a dispensing tool through a wellbore, the dispensing tool including an enclosure containing plugging devices, and then opening the enclosure by cutting a material of the enclosure, thereby releasing the plugging devices from the enclosure into the wellbore at a downhole location. A dispensing tool can include a container having an enclosure therein, the enclosure including a flexible material that contains the plugging devices, and an end of the enclosure being secured to a member displaceable by an actuator. The enclosure material is cut in response to displacement of the member by the actuator. A plugging device can include at least one body configured to engage an opening in the well and block fluid flow through the opening, and multiple fibers including staple fibers or filaments formed into yarn.

The invention relates to a construction panel with high resistance to fire and to a method for producing a construction panel with high resistance to fire.

The invention relates to a construction panel with high resistance to fire and to a method for producing a construction panel with high resistance to fire.

PROBLEM TO BE SOLVED: To provide a concrete structure and a concrete slab, which, by using a continuous fiber-reinforced polymer material as a main reinforcing material or a tendon, and by mixing a short fiber reinforcing material in concrete, compensate for the mechanical shortcomings of the continuous fiber-reinforced polymer material, not rusting, and taking advantage of superior characteristics of the continuous fiber-reinforced polymer material, with low manufacturing cost and ultra-high durability.

MEANS TO SOLVE THE PROBLEM: In a concrete structure, in which a continuous fiber-reinforced polymer material is arranged as a main reinforcing material or a tendon, a short fiber reinforcing material consisting of an organic fiber is mixed in 0.5% or more with respect to an entire volume, the continuous fiber-reinforced polymer material is shaped like a rod or a stranded wire, a ratio Lf/Gm between a fiber length Lf of the organic fiber of the short fiber reinforcing material and a maximum aggregate diameter Gm of a concrete composition is 1.2 to 3.7, and an aspect ratio Lf/De when an equivalent diameter De, which is a cross-sectional area of the organic fiber converted into a circle diameter, is 30 to 69.

Provided herein are fiber reinforced cementitious materials and mixtures with increased crack resistance. The cementitious materials and mixtures include a cement and at least one carbon fiber. Also provide is a fiber reinforced cementitious mortar that includes the fiber reinforced cementitious material to which at least one of water, an aggregate material or a chemical admixture is added.

The present invention provides a crack repair material of a concrete vacuum tube segment using ultra-high performance concrete (UHPC) for a hyper-speed transportation system and a crack repairing method for the same capable of, in a case in which a vacuum tube segment of a hyper-speed transportation system, such as the Hyperloop, is manufactured using UHPC, repairing cracks formed in the UHPC vacuum tube segment easily and conveniently using a crack growth prevention material and a patch repair material and capable of immediately repairing cracks formed in the UHPC vacuum tube segment to secure airtightness so that operation of a vacuum pump is minimized and overload of the vacuum pump is prevented.

The present invention provides a concrete vacuum tube segment for a hyper-speed transportation system using ultra-high performance concrete (UHPC) and a manufacturing method thereof. A concrete vacuum tube segment for a hyper-speed transportation system can be easily manufactured using UHPC, in which shrinkage and structural cracking do not occur due to mixing a binder and a short fiber to secure airtightness on the basis of a maximum fill theory, and accordingly, shrinkage of the concrete vacuum tube segment can be reduced even in a partial-vacuum state in which the magnitude of drying shrinkage is very small and quick drying occurs; when mixing the UHPC, an antifoaming agent is mixed and a circular vacuum pump is used to remove generated entrapped air to minimize the entrapped air; and a capsule-type crack healing material, which is able to repair fine cracks, is compacted to secure airtightness of the concrete vacuum tube segment.

Disclosed is a method for preparing an uncalcined geopolymer-based refractory material. The method includes the steps of mixing a mineral powder, a fly ash, a metakaolin, and silicon carbide whiskers by ball milling to form a milled material; mixing the milled material with a sodium water glass solution and water to form a slurry; and curing the slurry to obtain the uncalcined geopolymer-based refractory material. The uncalcined geopolymer-based refractory material thus prepared contains a geopolymer matrix formed of the mineral powder, the fly ash, and the metakaolin and the silicon carbide whiskers embedded in the geopolymer matrix.