Universitat Kassel

Universitaet Dortmund

Universität Dortmund

Bernhard Middendorf

Maik Feldmann

Armin Just

Juergen Neisecke

Hans-Peter Heim

Ekkehard Fehling

Alexander Wetzel

Philipp Krooss

Thomas Niendorf

Werner Seim

Ralf Urs Giesen

Michael Hartung

Kevin Klier

Viola Sauer

Siemon Piotrowski

Jana Simon

Jürgen Neisecke

A method is provided for producing a microfiber-reinforced high-strength concrete, comprising a cement matrix with a microfiber addition. The fiber elements have a shape-memory alloy. The method has at least the following steps: training a fiber shape of the fiber elements at a temperature above a transition temperature, wherein the fiber shape allows the fiber elements to latch; cooling the trained fiber elements; plastically deforming the fiber elements from the trained fiber shape into an intermediate form by means of which the fiber elements are prevented from latching; introducing the fiber elements into the cement matrix in order to form a fresh concrete; and casting the fresh concrete and heating the fresh concrete to the transition temperature such that the fiber elements reform into the fiber shape, thereby latching the fiber elements. The invention additionally relates to a microfiber-reinforced concrete which is produced using such a method.

Microfiber-reinforced high-strength concrete

The invention relates to an expanded concrete composed of binder-containing mixtures, preferably having binders composed of Portland cement as specified in DIN EN 197 or of mixtures of hydraulic, latent-hydraulic and/or pozzolanic binders, having binders, water with a fraction of 20-60% by mass based on the mass of the binder in the mixture, chemical gas-forming agent, preferably in the form of aluminum powder, at 0.05-0.25% by mass, based on the mass of the binder, for forming mostly air pores in the expanded concrete, wherein the gas-forming agent in the form of a powder forms a mixture of different particle sizes, concrete additives such as in particular microsilica and/or flyash with a fraction of 0.5-25% by mass, based on the mass of the binder, concrete admixtures of mostly liquefying character and at a fraction of 0.5-5% by mass, based on the mass of the binder, wherein the distribution of the air pores of different sizes in the matrix of the expanded concrete, depending on its consistency, makes possible a compressive strength up to 30 N/mmafter curing, and the expanded concrete is air-curing at atmospheric pressure under normal ambient temperature. In addition, a method is proposed of producing such an expanded concrete, and also a test method of determining the fresh concrete properties of an expanded concrete according to the invention.

Air-curing expanded concrete composed of binder-containing mixtures

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Calden, Germany

Bernhard Middendorf