A concrete-based composite material including iron rich particles is characterized by an iron content greater than 17% by weight of the composite material, can include iron particles which are an iron by-product recovered from iron slag material, can include iron rich particles which have an iron content of at least 60% by weight of the iron rich particles, and/or can include iron particles having a particle size distribution in the range of about −⅜ inch to +60 mesh or in the range of about −20 mesh to about +60 mesh. The composite material can include ground granulated blast furnace slag as a portion of the cementitious component of the composite material. A method of forming a structural element from the composite material includes casting the structural element such that the structural element is characterized by a ballistic performance of Level 10 as defined by Underwriters Laboratories standard UL752.

Ultra-high performance concrete produced from cement, aggregate, water, fillers, and additives, wherein the aggregate comprises 800-1,300 kg of an igneous rock in the form of crushed stone per cubic meter of concrete.

A concrete comprises in relative parts by weight: 100 of Portland cement; 0.25 to 9 of a defoamer; 0.001 to 6 of a surfactant; 0 to 230 of coarse gravel and/or fine gravel and/or shear enhancers; 0 to 85 of sand; 0 to 60 of a particulate pozzolanic or non-pozzolanic material or a mixture thereof having a mean particle size less than 15 micrometers; 0 to 80 of a particulate pozzolanic or non-pozzolanic material or a mixture thereof having a mean particle size between 15 to 88 micrometers; 0.3 to 18 of a water-reducing superplasticizer; 0 to 14 of polyethylene fibers; and 5 to 40 of water. An air mixing process using a tightly sealed mixing tool is used to thoroughly mix the constituents of the concrete before adding the water for curing. By adjusting relative parts in the composition, concretes of high and ultrahigh performance can be achieved efficiently.

Methods of forming a carbon fiber reinforced carbon foam are provided. Such a method may comprise heating a porous body composed of a solid material comprising covalently bound carbon atoms and heteroatoms and having a surface defining pores distributed throughout the solid material, in the presence of an added source of gaseous hydrocarbons. The heating generates free radicals in the porous body from the heteroatoms and induces reactions between the free radicals and the gaseous hydrocarbons to form covalently bound carbon nanofibers extending from the surface of the solid material and a network of entangled carbon microfibers within the pores the porous body, thereby forming a carbon fiber reinforced carbon foam. Carbon fiber reinforced carbon foams and ballistic barriers incorporating the foams are also provided.

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.

A foam concrete has constituents that include a cement, a sand, a coarse aggregate, an oil ash, a water, and a foam solution. The foam concrete has a compressive strength of at least 20 MPa, a thermal conductivity of less than 0.41 W/mK and a maximum weight of 1650 kg/m.sup.3.

Calcium silicate-based cements and concretes are disclosed, which result in concrete compositions that have an improved strength development. A cement product includes a plurality of particles of a carbonatable calcium silicate cement and a first additive; wherein, the first additive is an organic molecule with at least one primary, secondary or tertiary amine group.

Provided is a cement composition that has high fluidity (for example, a 0-drop flow value of 200 mm or more) before curing and exhibits high compressive strength (for example, 320 N/mm.sup.2 or more) after curing. The cement composition includes a cement, a silica fume having a BET specific surface area of from 10 m.sup.2/g to 25 m.sup.2/g, an inorganic powder having a 50% cumulative particle size of from 0.8 μm to 5 μm, a fine aggregate having a maximum particle size of 1.2 mm or less, a water reducing agent, an antifoaming agent, and water. The ratio of the cement is from 55 vol % to 65 vol %, the ratio of the silica fume is from 5 vol % to 25 vol %, and the ratio of the inorganic powder is from 15 vol % to 35 vol % in the total amount of 100 vol % of the cement, the silica fume, and the inorganic powder.

The present invention relates to epoxy curing agents which are obtained from the reaction of a polyalkylene polyether modified polyepoxide resin and a polyamine component. They polyamine component is a reaction product of a polyethylene polyamine having 3 to 10 nitrogen atoms, for example, diethylenetriamine (DETA), and at least one aldehyde having 1 to 8 carbon atoms, for example, formaldehyde. The epoxy curing agent may be used as part of a two component coating system in the curing of liquid or pre-dispersed curable epoxy resins.

A seismic steel tubular column with internal local restraint and filled with high strengthen compound concrete containing normal-strength demolished concrete lumps, and a construction process. The seismic column includes a steel tube (1), high-strength fresh concrete (2), normal-strength demolished concrete lumps (3), horizontal stirrups (4), and longitudinal erection bars (5). The horizontal stirrups (4) are arranged at upper and lower ends inside the steel tube (1). The high-strength fresh concrete (2) is poured and the normal-strength demolished concrete lumps (3) are put alternately inside the steel tube (1). A compressive strength of the high-strength fresh concrete (2) is 30˜90 MPa greater than that of the normal-strength demolished concrete lumps (3).