An embodiment includes a Class C fly ash (CFA) cementitious composition with a controllable setting time comprising at least one Class C fly ash; at least one alkali hydroxide; at least one source of phosphate; and water. Alternate embodiments include a Class C fly ash (CFA) cementitious composition with a solid activator comprising at least one Class C fly ash; at least one alkali carbonate; at least one source of phosphate; and water.

According to some embodiments, a curable mixture configured to set in the presence of water, wherein the mixture comprises magnesium oxide, a primary cementitious component and at least one accelerant. A proportion by weight of the primary cementitious component is 80% to 120% of a proportion of magnesium oxide by weight.

A method may include providing a cement composition comprising ground vitrified clay, hydrated lime, and water; and introducing the cement composition into a subterranean formation.

A structural barrier and energy absorbing device comprising a plurality of structural elements is provided. 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.

Methods of recovering coal combustion products (CCPs) from coal combination byproducts are disclosed. The methods include compiling coal combustion byproducts (e.g., lignite coal and/or bituminous coal), grinding the coal combustion byproducts to form ground coal combustion byproducts with a maximum particle size of 40 microns, and separating the ground coal combustion byproducts to yield CCPs using an electrostatic precipitator. The following CCPs can be separated from the coal combination byproducts using the presently disclosed methods: fly ash, bottom ash, scrubber materials, and raw coal.

A method may include providing a cement composition comprising ground vitrified clay, hydrated lime, and water; and introducing the cement composition into a subterranean formation.

According to some embodiments, a curable mixture configured to set in the presence of water, wherein the mixture comprises magnesium oxide, a primary cementitious component and at least one accelerant. A proportion by weight of the primary cementitious component is 80% to 120% of a proportion of magnesium oxide by weight.

The present invention provides an apparatus and a method for producing cement through flue gas desulfurization, and specifically provides an apparatus and a method for simultaneously producing magnesium sulfate cement during a magnesium oxide based flue gas desulfurization process. The apparatus of the present invention includes a flue gas desulfurization equipment, a concentration equipment, a crystallization equipment, a centrifugation equipment, a drying equipment, a waste ash supplying equipment, a slag material supplying equipment, a mixing equipment, etc. By adopting the apparatus and method of the present invention, the problems in the present conventional cement production such as high energy cost, severe damage to the environment and so on can be solved, and the problems like high production cost of ordinary magnesium sulfate cement and high transportation cost of supplies thereby causing incapability in a large scale market spreading and application can also be solved.

The present invention provides an apparatus and a method for producing cement through flue gas desulfurization, and specifically provides an apparatus and a method for simultaneously producing magnesium sulfate cement during a magnesium oxide based flue gas desulfurization process. The apparatus of the present invention includes a flue gas desulfurization equipment, a concentration equipment, a crystallization equipment, a centrifugation equipment, a drying equipment, a waste ash supplying equipment, a slag material supplying equipment, a mixing equipment, etc. By adopting the apparatus and method of the present invention, the problems in the present conventional cement production such as high energy cost, severe damage to the environment and so on can be solved, and the problems like high production cost of ordinary magnesium sulfate cement and high transportation cost of supplies thereby causing incapability in a large scale market spreading and application can also be solved.

A cementitious binder, includes a hydraulic binder in an amount in the range from 50 to 80% by weight of the cementitious binder; a first siliceous based material in an amount in the range from 0.5 to 35% by weight of the cementitious binder, the first siliceous based material having a (SiO.sub.2)/(Al.sub.2O.sub.3) ratio by weight greater than 2.5; a second siliceous based material in an amount in the range from 10 to 25% by weight of the cementitious binder, the second siliceous based material being different from the first siliceous based material and having (a) a (SiO.sub.2)/(Al.sub.2O.sub.3) ratio by weight greater than 10 and (b) a BET specific surface area greater than 5 m.sup.2/g; and an aluminum based material in the range from 0 to 10% by weight of the cementitious binder and having a (SiO.sub.2)/(Al.sub.2O.sub.3) ratio by weight lower than 2.5, wherein 0.09<Al.sub.EFF/(Al.sub.EFF+Si.sub.EFF)<0.28, where Al.sub.EFF=molar content of alumina aluminum in the hydraulic binder, and Si.sub.EFF=molar content of silica in the first siliceous based material for particles having a size lower than 3 m+molar content of silica in the second siliceous based material.