Making building material mixture for magnesium oxide concrete, comprises selecting particle distribution and particle shape of quartz surcharge and selecting a mixing solution based on magnesium chloride content and solution equilibrium

摘要

Producing building material mixture, based on magnesium oxide as a binder, and an aqueous magnesium chloride-containing mixing solution and quartz sand as aggregate, comprises selecting particle distribution and particle shape of quartz surcharge for adjusting the strength of building material mixture and sprayability; selecting a mixing solution based on magnesium chloride content and solution equilibrium compared to upcoming rock salt; and selecting magnesium oxide based on magnesium chloride solution consumption for adjusting the sprayability. Producing building material mixture, based on magnesium oxide as a binder, and an aqueous magnesium chloride-containing mixing solution and at least a quartz sand as aggregate, or a suspension of magnesium oxide and an aqueous magnesium chloride-containing mixing solution as a binder and at least a quartz sand as an aggregate, comprises selecting particle distribution and particle shape of at least a quartz surcharge for adjusting the strength of the building material mixture and sprayability; selecting a mixing solution based on magnesium chloride content and solution equilibrium compared to the upcoming rock salt; and selecting magnesium oxide based on magnesium chloride solution consumption to achieve standard stiffness in accordance with a test method according to DIN EN 14016-2 for adjusting the sprayability, or for adjusting the conveyance in spray system and sprayability. Independent claims are included for: (1) the building material mixture for producing magnesium oxide concrete for cavities to be closed and mine workings in rock salt in dry spraying process, obtained by the above process, where: ingredients (I) are provided as average mass fractions with specified tolerances in a dry spray formulation; (I) comprise R-solution (10 +- 2 mass%), magnesium oxide product (15 +- 3 mass%) and aggregate (75 +- 5 mass%), powdered magnesium oxide calcined from caustic magnesite is used as magnesium oxide product, and the magnesium oxide product exhibits magnesium chloride solution consumption of = 60 mass% to achieve the standard stiffness in accordance with a test method according to DIN EN 14016-2; the ingredients comprise R-solution (15 +- 3 mass%), magnesium oxide product (17 +- 3 mass%) and aggregate (68 +- 6 mass%), and the magnesium oxide product exhibits magnesium chloride solution consumption of greater than 60 mass% to achieve the standard stiffness in accordance with a test method according to DIN EN 14016-2; and powdered magnesium oxide calcined from caustic magnesite is used as magnesium oxide product; (2) the building material mixture for producing magnesium oxide concrete for cavities to be closed and mine workings in rock salt in suspension spraying process, obtained by the above process, where: ingredients (II) are provided as average mass fractions with specified tolerances in a suspension spray formulation; (II) comprise R-solution (15.5 +- 3.5 mass%), magnesium oxide product (15.5 +- 3.5 mass%) and aggregate (69 +- 7 mass%), and the magnesium oxide product exhibits magnesium chloride solution consumption of = 60 mass% to achieve the standard stiffness in accordance with a test method according to DIN EN 14016-2; (II) comprise R-solution (17.5 +- 3.5 mass%), magnesium oxide product (17.5 +- 3.5 mass%) and aggregate (65 +- 7 mass%), and the magnesium oxide product exhibits magnesium chloride solution consumption of greater than 60 mass% to achieve the standard stiffness in accordance with a test method according to DIN EN 14016-2; and powdered magnesium oxide calcined from caustic magnesite is used as magnesium oxide product; (3) a device for the production of building materials, comprising a dry spray nozzle as its end part, where the dry spray nozzle is provided with a means for compressed air delivery and a means for pump conveying, the dry mixture comprising additives, the caustic magnesium oxide and the aggregate is fed via the means for compressed air delivery, the mixing liquid containing magnesium chloride-containing salt solution is fed in a saturation region via the means for pump conveying and the dry spray nozzle is delivered via pressure pipes; and (4) a method of applying building material mixtures for forming magnesium oxide concrete to cavities to be closed and mine openings in rock salt via the device, comprising cleaning the surface of the rock salt on which the building material mixture is applied by sandblasting in dry blasting process, applying a layer of 1-10 mm thickness of first magnesium oxide building mixture with a particle size of maximum 1 mm, as primary layer, setting the applied magnesium oxide building mixture and applying a second magnesium oxide-building mixture with a particle size of up to maximum 8 mm as a final protective layer on the primer layer and curing the magnesium oxide-building mixture to magnesium oxide concrete.