Abstract:
PROBLEM TO BE SOLVED: To provide a concrete mixture containing an organic fiber for reinforcement and having especially improved tensile stress (flexure and direct tensile stress) compared to concrete mixtures of conventional technology.SOLUTION: The concrete containing a cured cement matrix is obtained by dispersing an organic fiber and, in addition, mixing a composition containing (a) cement, (b) a granular material showing 20 to 60 mass% of the cement matrix, (c) a fine material by a pozzolanic reaction and (d) at least one kind of dispersant with water, and further (1) the granular material (b) has a maximum particle size of 2 mm at maximum, (2) the fine material (c) by the pozzolanic reaction in the composition has a material particle size of 20 μm at maximum, and further (3) mass percentage of water to the added mass of the cement (a) and the fine pozzolanic reaction material (c) is in a range of 8% to 25%, (4) the organic fiber has each length I of at least 2 mm and I/φ ratio of at least 20, where φ is a fiber diameter, (5) the amount as volume of the fiber is the amount showing 8% of the concrete volume after aggregation at maximum, and (6) a ratio R between an average fiber length L and maximum particle size of the fine material D is at least 5.
Abstract:
PROBLEM TO BE SOLVED: To provide an improved type method for spraying concrete or mortar by a dry process or a wet process in order to apply a concrete or mortar layer to a surface. SOLUTION: Just before a spraying means or at a spot of the spraying means, aqueous suspension (A) of aluminum compound selected from silica and aluminum, basic aluminum sulfate, alum, and their mixture is added. Herein, the aqueous suspension (A) has a pH