NON METALLIC (MCP) FIBER REINFORCED CONCRETE: MECHANICAL CHARACTERIZATION AND SLABS ON GRADE DESIGN ASPECTS

摘要

Fiber Reinforced Concrete (FRC) is widely used for elements of secondary structural importance (slabs on grade, tunnels, railway superstructures). Steel fibers are the most commonly adopted. However, at high fibers volume ratios, some difficulties could be found in obtaining a good homogeneity of the steel fibers in the concrete matrix with consequent non-homogeneity of the material characteristics. This paper deals with experimental evaluation of flexural performances of non metallic (Modified Copolymer of Polypropylene, MCP) Fiber Reinforced Concrete (MPFRC) and related design aspects for slabs on grade. The experimental program involves splitting tests of cylindrical specimens, compression tests and four point bending tests on notched and un-notched specimens. MPFRC results of four points bending tests were compared with results of hooked Steel Fiber Reinforced Concrete (SFRC) with the same volume ratio. MPFRC specimens showed more consistent results, thus confirming the more homogeneous distribution of fibers in concrete. Different concrete strengths and fiber volume ratios were investigated. Based on the experimental results, the constitutive law of the fiber reinforced concrete is determined. The constitutive law allows slabs on grade design considerations referring to the Ultimate Limit State and Serviceability Limit State.