A structural barrier and energy absorbing device comprises a plurality of structural elements. The structural element alone or in a plurality may serve as a traversal impediment or energy absorbing device, such as a pedestrian barrier, vehicular barrier, anti-tank obstacle, ballistic barrier, or the like. The structural element may be a tetrapod such that it comprises an element body having four extension portions that extend outwardly from the interior center to a distal end, such that the structural element maintains an identical orientation and a low center of gravity in each of four resting positions. The structural element may be a solid-state structural element comprised of a particular material or a portable and collapsible structural element wherein the element body comprises an outer skin defining an interior void space, such that during set-up or installation the interior void space may be filled with a filler substance onsite.

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.

A high performance concrete composition comprising: (i) at least one Class C fly ash, (ii) at least one calcium aluminate cement, (iii) at least one aggregate, and (iv) water.

The present invention belongs to the field of composite materials, and particularly to a non-flowable quick-setting phosphate cement repair material with strong cohesive forces and the preparation method thereof. The material comprises the following raw materials in percentage by weight: 20% to 40% of sand, 5% to 12% of ammonium dihydrogen phosphate, 10% to 25% of magnesium oxide, 2% to 8% of fly ash, 30% to 60% of rubber powder, 6% to 10% of silica fume, 0.35% to 0.6% of a polycarboxylate high efficiency water-reducing agent, 1% to 5% of sodium silicate, 1.5% to 2% of a polypropylene fiber, 0.5% to 2% of a retarder, and 8% to 10% of water. The material is used as the repair material for the special positions of bottom boards of bridges or facades of buildings which are damaged, and the repair effect thereof is remarkable.

A geopolymeric material is described having compressive strength at 28 days ranging from 15 to 100 N/mm.sup.2, obtainable by curing for 12 hours at a temperature ranging from 20° C. to 60° C., from a geopolymeric aqueous mixture comprising the following inorganic components in the following parts by dry mass: metakaolin 1565 potassium silicate and/or sodium silicate 2040 aggregates recycled from CDW (Construction and Demolition Waste) 5300; said geopolymeric aqueous mixture is obtainable by mixing 20175 parts by mass of water with said inorganic components, and has a viscosity at 23° C. between 100 and 10000 Pa.Math.s, wherein: i) the viscosity is measured via Brookfield methodology, ii) the aggregates recycled from CDW belong to one or more of the classes 17.01.01, 17.01.02, 17.01.03, 17.01.07 according to the European Waste Catalogue, iii) the aggregates recycled from CDW have a grain size less than or equal to 4 mm, preferably less than or equal to 2 mm.

A method may include: defining engineering parameter of a proposed cement slurry, the engineering parameters comprising at least a compressive strength requirement, a density requirement, a storage time requirement, and a thickening time requirement; selecting, based at least in part on a model of compressive strength, a model of storage time, and the density requirement, at least a cement and mass fraction thereof, at least one supplementary cementitious material and mass fraction thereof, and a water and mass fraction thereof, such that a cement slurry formed from the cement, the at least one supplementary cementitious material, and the water meets the compressive strength requirement and the density requirement; selecting, based at least in part on a model of thickening time, an accelerator and mass fraction thereof; selecting, based at least in part on a model of activator thickening time, an activator and mass fraction thereof; and preparing a cement slurry comprising the cement and mass fraction thereof, the at least one supplementary cementitious material and mass fraction thereof, the water and mass fraction thereof, and the cement retarder and mass fraction thereof.

Cement compositions containing a hydraulic cement, a synthetic phyllosilicate (e.g. Laponite®), and silica flour. The cement compositions may optionally include other additives such as an expandable agent, a defoamer, and a fluid loss controller. Cement slurries and wellbore cements made therefrom are also specified. The inclusion of the synthetic phyllosilicate has enhanced the mechanical strength, improved the density homogeneity, as well as decreased the permeability of the wellbore cement, making it suitable for cementing oil and gas wells under high pressure and high temperature (HPHT) conditions.

In various embodiments, a process is described for the preparation of a concrete mixture in a Ready-mix or for an installation. A quantity of amorphous silica is added with an average particle size in the range of from about 1 to about 55 nanometers and/or wherein the surface area of the particles of the amorphous silica is in the range of from about 300 to about 900 m2/g. The amorphous silica may be added in colloidal form or otherwise, and is added at a particular stage to ensure efficacy.

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.