Abstract
The paper presents the results from the research on self-compacting concrete with different steel fibre type addition. The reference self-compacting concrete mix with water/binder = 0.33 was prepared, then modified with steel fibres in the amounts of 0–60 kg/m3 and air entrained with polymer microspheres (40 μm diameter). The major objective of the research was to determine the effect of steel fibre and air content on the self-compacting concrete mix properties and hardened concrete frost durability. The tests also included internal cracking and scaling resistance evaluation for concrete specimens subjected to cyclic freeze-thaw process − two beams were frozen in air and two beams were partially submerged in water and then frozen. The scaling resistance was tested using the slab method on the specimens with sawn surface and on the specimens with natural finished surface. Non-air entrained steel fibrereinforced concretes, despite their high strength class (C55/67–C60/75) and medium absorption (4.34–5.11%), showed unsatisfactory resistance to internal cracking and scaling tests. The beams partially submerged in water failed after 100 freeze-thaw cycles, which confirms a significant influence of water uptake from moist environment during freeze-thaw cycles and the acceleration of the damage process. Test results indicate that air entrainment with polymer microspheres is a very effective method and allows obtaining very good air pore structure parameters and frost resistance results. The specimens with top − finished surface exhibited less damage in the scaling resistance tests in relation to the specimens with sawn surface.
Highlights
Over the last several years rapid advancement has been observed in the technology of self-compacting concrete (SCC) and its use in ready-mix concrete applications, production of precast concrete products and repairs of the existing structures
This paper discusses the results of the experimental program carried out to investigate the effect of steel fibre and air content on the self-compacting concrete mix properties, frost durability and the mechanical properties of hardened concrete
Two series of air entrained and nonentrained concrete were made with varied amount of steel fibre content (0–60 kg/m3)
Summary
Over the last several years rapid advancement has been observed in the technology of self-compacting concrete (SCC) and its use in ready-mix concrete applications, production of precast concrete products and repairs of the existing structures (bridges, tunnels etc). A smooth, crack-free and impermeable concrete able to resist chloride attacks and freezing and thawing processes is required for durability. This quality concrete is made with a special mix with powders and a very low water-cement ratio of 0.35 (Rostam 1996). The research results (Wawrzeńczyk, Molendowska 2011) showed that the application of polymer microspheres as an air entraining agent confirmed high efficiency of this method for traditional bridge concrete. Few publications describe mix design problems or deal with practical application of high frost durable steel fibre-reinforced self-compacting concrete pavement concretes. The SCC was made from CEM I 42.5 cement, limestone filler and the air-entraining agent at W/C = 0.40, and an addition of 30−44 kg/m3 steel fibre. The innovative and highly efficient method of concrete air-entrainment with the application of polymer microspheres 40 μm in nominal diameter was used for that purpose
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