Abstract
Sprayed fiber-reinforced concrete is used in construction for the execution and repair of reinforced concrete elements. It is believed that the addition of steel fibers is most effective, due to their parameters and low costs. Some researchers, however, suggest that the addition of steel fibers can contribute to the initiation of corrosion of the main reinforcement. In consideration of the differences of opinion on the corrosion resistance of sprayed fiber-reinforced concrete, it has become necessary to analyze this issue. The article presents comparative studies of corrosion assessments of the main reinforcement in specimens made of ordinary concrete and concrete with steel fibers. The tests were performed using a semi non-destructive galvanostatic pulse method, which allows location of the areas of corrosion and estimation of the reinforcement corrosion activity. In order to initiate the corrosion processes the specimens were subjected to freezing cycles in NaCl solution. In addition, the shrinkage and compressive strength of specimens were measured, and the observation of specimen structure under a scanning microscope was performed. It was found that galvanostatic pulse method allowed estimation of the reinforcement corrosion progress. The corrosion of the main reinforcement in steel fiber reinforced concrete specimens was less advanced than in the specimens without fibers.
Highlights
Sprayed concrete [1,2,3] is frequently used as a filling material, a protective and finishing material for repairs of civil engineering structures and industrial structures, or in the reconstruction of damaged historic buildings, in the case of limited or difficult access [3,4,5,6,7]
Repairs with sprayed concrete can be performed by casting the concrete mix onto thin-wired steel meshes placed on the surfaces of the repaired elements, or by using fiber-reinforced concrete (FRC), i.e., concrete with dispersed reinforcement in the form of various fibers, which eliminates the need for meshes [2,3,8,9]
In order to simulate the impact of an corrosive environment and above which made it possible to determine the differences in trigger the corrosion process on the reinforcement, the specimens were exposed to freezing cycles in the corrosion rates of the primary reinforcement in plain concrete and fiber-reinforced concrete with
Summary
Sprayed concrete (shotcrete) [1,2,3] is frequently used as a filling material, a protective and finishing material for repairs of civil engineering structures and industrial structures (mainly in concrete cover and to protect steel against corrosion), or in the reconstruction of damaged historic buildings, in the case of limited or difficult access [3,4,5,6,7]. Electrochemical cracking thede-iced concrete, opening the way forwhich chloride ions (NaCl) which diffuse concrete cover corrosion is the often by frost, as theon water freezingofinthe the concrete pores generates stress, reactions result in mediated corrosion cells forming the surface reinforcement, and the corrosion and damage passive film which protects the reinforcement. As previously mentioned, shotcreting is usually applied in construction and renovation works on industrial or civil engineering structures which are exposed to higher risk of corrosion, and for which the structural integrity requirements are much higher than in residential or public buildings [6,30] For this type of work, using fiber-reinforced concrete (in particular SFRC), i.e., a composite with higher waterproofing and freeze–thaw durability parameters, appears reasonable. In consideration of the differences of opinion on the corrosion resistance of sprayed FRC with dispersed steel reinforcement described above, it has become necessary to analyze this issue both in laboratory conditions and in situ
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