Properties of Ultra-High-Strength Self-Compacting Fiber-Reinforced Concrete

摘要

It is known that characteristics of fiber-reinforced concrete generally depend on the volume and properties of the matrix, the type and dosage of fiber. Studies have been conducted on the influence of these factors on strength and deformation characteristics, including the modulus of elasticity, creep and frost resistance of ultra-high strength self-compacting fiber reinforced concrete (UHSFRC). Portland cement CEM I 52.5, sand with fineness modulus of 2.5, organic-mineral modifier MB-50 and straight steel fiber were used as components for self-compacting concrete. The fiber dosage was varied in the range from 0 to 2.0% of the volume of concrete mixtures. The tests have shown that the creep of steel fiber reinforced concrete at different levels of loading (0.3 and 0.6 of Rb) is significantly less than that of the matrix. The ratio of transverse creep deformation is significantly lower than under the short-time loading, as for the matrix and the same as for steel fiber reinforced concrete. Despite almost linear diagram of concrete deformation under compression, the value of creep deformation shows quite higher figures. It is noted that the effectiveness of steel fiber increases with the increase of stress level. Freeze-thaw resistance was evaluated in the cyclic process of freezing at -50℃ [-58℉] and thawing in 5% NaCl solution. The test results show very high frost resistance of concrete, what corresponds to the grade F_2800, what is 2.7 times above the concrete requirements for transport structures in Russia.