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US 4,804,563 AGranted
Method and apparatus for the spray placing of concrete layers
AssigneeHochtief Aktiengesellschaft Vorm. Gebr. Helfmann
InventorsBernd Hillemeier, Gunter Brockmann, Richard Pohl
Life of this patent
Estimating the term…
Abstract
A spray concrete composition which is sprayed with driving-air pressure has its setting time accelerated by incorporation in the driving air of amorphous silica dust having an inner surface (specific surface area) of at least 25 m.sup.2 /g.
Claims9
A method of applying spray concrete to a surface to be concreted, comprising the steps of:
- (a) forming a pumpable and sprayable settable concrete composition consisting at least of a hydraulic cement, an aggregate and water;
- (b) entraining said composition in a stream of driving air at a driving pressure to form a spray of said composition and cause particles of said spray to deposit on said surface to be conceted and set as a layer of concrete thereon;
- and
- (c) admixing with said air before it entrains said composition a quantity of silica dust having an inner surface area of substantially 200 to 700 m.sup.2 /g and sufficient to interact with said composition upon contact therewith and spontaneously raises the temperature thereof by substantially 5 to 10 degrees Kelvin and thereby accelerate the setting of said concrete on said surface.
1 more element
Dependencies are inferred from the claim text.