The paper presents the results of investigations of properties (consistency, air content, density, water absorbability, freeze resistance, compressive and bending strength) of ordinary concretes as well as concretes containing various amount of steel fibres. To make the samples, the Portland cement CEM II/B-M (V-LL) 32.5 R and natural aggregate with graining of 0÷16 mm (with increased quantity of sand – 38%) were used. The concrete samples with addition of steel fibres were made in three batches where the added fibres constituted 0.8%, 1.6% and 2.4% of the mass of concrete mix. After the tests it was stated that the admixture of steel fibres causes the increase (to a small extent) of the density and air content in the concrete mix, the water absorbability of the concrete, moreover it has positive influence on the strength properties. In the freeze resistance tests, the cubes made of the modified concrete presented lower compressive strength with the increase of the quantity of steel fibres.

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