The invention relates to a cementitious multi-component mortar system comprising finely ground Portland cement clinker with a grinding fineness in the range of from 6000 to 12000 cm.sup.2 g, for use as an inorganic chemical fastening system for anchoring elements in mineral substrates.

A multi-component inorganic capsule anchoring system can be used for chemical fastening of anchors, bolts, screw anchors, screw bolts, and post-installed reinforcing bars in mineral substrates. The multi-component inorganic capsule anchoring system contains a curable powdery ground-granulated blast-furnace slag-based component A, and an initiator component B in aqueous-phase for initiating the curing process. The powdery ground-granulated blast-furnace slag-based component A contains further silica dust. The component B contains an alkali- or alkaline earth-hydroxide, alkali- or alkaline earth-carbonate, or alkali-or alkaline earth-sulfate component.

A green concrete and mortar compositions free of Portland cement are disclosed. The compositions comprise Natural pozzolan, nanosilica particles, and alkaline activator. The green concrete produced from the composition of the invention is cured at ambient temperature and has higher compressive strength than that of concrete made with Portland cement.

A concrete durability protection method is provided, including following steps: Step one: rinsing the concrete surface; Step two: spraying agent A material or alternately spraying agent B material and agent A material at the wet surface of the concrete; Step three: repeating step two. The beneficial effects of the present invention include: nanoscale active silicate penetrates into the concrete surface layer within a certain depth and reacts with free calcium ions within the concrete to form C—S—H crystalline, thereby improving the compactness of the concrete surface layer within a certain depth, repairing defects in the concrete surface layer within a certain depth, such as the capillary interstices, pores, microcracks, etc., so as to effectively improve the durability of concrete. The unreacted nanoscale active silicate material has permanent activity. It could recover its activity when the concrete absorbs moisture, and continue to react with free calcium ions in the concrete to quickly form C—S—H crystals, realizing the permanent concrete durability protection.

Disclosed is a method of cementing. The method comprises providing a set-delayed cement composition comprising water, pumice, hydrated lime, a set retarder, and a micro-electrical-mechanical system; and allowing the set-delayed cement composition to set.

Disclosed is a method of spraying a surface with a set-delayed cement. The method comprises providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; spraying a surface with the set-delayed cement composition; and allowing the set-delayed cement composition to set on the surface.

A concrete composition and method include a portion of fine aggregate bearing a coating of a polymer, which may be a continuous coating layer or a layer of powdered, discrete particles embedded in a binder. The polymeric coating may be a super absorbent polymer (insoluble in water, but absorbing water), or another polymer such as the acrylamides, co-polymers thereof, polyacrylamides, or the like (soluble in water). The coating absorbs water, but particles are too small to form significant voids. Water is absorbed into the concrete mix in far greater proportions (e.g. w/c ratio over 0.5) improving workability, doubling workability time, and improving ultimate compressive stress (strength).

A cement mixture is disclosed that includes an aqueous mending agent that is disbursed within but isolated from the cement mixture, wherein the aqueous mending agent will form molecular bonds with hardened cement that is formed by the cement mixture when the mending agent is permitted to flow within the hardened cement.

Methods of using extended-life cement compositions are disclosed. A method comprises providing an extended-life cement composition comprising calcium-aluminate cement, water, and a cement set retarder. The method additionally comprises mixing the extended-life cement composition with a cement set activator to activate the extended-life cement composition. The method further comprises Introducing the activated extended-life cement composition into a subterranean formation and allowing the activated extended-life cement composition to set in the subterranean formation; wherein the activated extended-life cement composition has a thickening time of greater than about two hours.

A method for conditioning an acid waste by cementation, wherein the acid waste is chosen among liquids having a pH of no more than 4, semi-liquids having a pH of no more than 4, solids of which the partial or full dissolution in water leads to a solution or suspension having a pH of no more than 4, and mixtures thereof, which method comprises the steps of: a) preparing a cement paste having as components at least: a magnesium phosphate cement and the acid waste, and b) hardening the cement paste thus obtained, and is characterised in that in step a), the cement paste is prepared without subjecting beforehand the acid waste to any treatment consisting in reducing the acidity thereof.