Design And Fabrication Of Anti-corrosion Scaleboard For Concrete And Its Properites Research

With excellent performance of high strength, good corrosion resistance and fatigue resistance, fiber reinforced polymer(FRP) composites have been widely applied in strengthening and protecting the concrete structures in civil engineering. Based on FRP and under the consideration of prefabricate and effective bond, a novel technology of surface scaleboard used for concrete protection was developed by the use of function bridging material instead of adhesive, and a prefabricated roughing FRP sheet(RFS) was manufactured. RFS could become a unit with concrete after casted, without any treatment for concrete surface, when compared to the traditional use of coating and FRP, which has a great potential to be widely used in concrete protection. In this paper, bond properties and durability of RFS were studied systematically, technology of construction and repair were discussed primarily.Texture depth and bond strength increased with the increasing of particle size of bridging material, and the use of lightweight aggregate with a particle size at 3.15~4.75 mm as bridging material reached the highest average bond strength of 2.17 MPa. Bond strength of the RFS-concrete substrate systems is mainly determined by mechanical interlocking and interfacial structure, bridging material with porous structure has many advantages including lightening self-weight and strengthening the interlocking of bridging material between resin and cement paste. With a certain bridging material and concrete, bond performance of the RFS-concrete substrate systems relate to the factors including size, gradation, designed density and plot ratio, the average failure bond stress can be formulated as F = K1 hsp + K2D50 + K3.Silane coupling agent(SCA) was introduced as modifying material to further improve the bond quality between RFS and concrete substrate. Results indicated that water absorptivity of lightweight aggregate can be controlled by SCA solutions, pull-off bond strength, mechanical strength, microhardness were increased, which were attributed to the optimized components and microstructure of interfacial transition zone(ITZ) under the condition of an appropriate concentration of SCA. In this study, concentration of 0.05% creates a relatively better performance.Bond behavior of RFS-concrete substrate was evaluated under complex environment conditions stimulating the durability of service environment, including chloride corrosion, temperature impact, seawater drying-wetting cycle, ultraviolet aging and fatigue load. Results indicated that RFS showed good resistance to chloride ion permeability. After treatment of temperature impact and seawater drying-wetting for 90 cycles, the appearance of RFS showed no evident change and the bond strength were significantly decreased 79.3%, 54.8%, respectively. After ultraviolet aging for 2000 h, the color of RFS turned yellow and deeper, and the bond strength was significantly decreased 59.6%. The effect of SCA on durability of RFS-concrete substrate during the difference service environment showed remarkable differences. SCA had no effect on improving bond quality of RFS under temperature impact, while had obvious effects under seawater drying-wetting cycle. For specimen modified by concentration of 0.05% SCA solution, after treatment of temperature iMPact and seawater drying-wetting for 90 cycles, bond strength were significantly decreased 79.3% after treatment of temperature impact, while a little decrease of 34.0% after seawater drying-wetting cycle. For specimen surface treated with acrylic resin, after ultraviolet aging for 2000 h, the bond strength was decreased only 28.5%, indicating that the use of surface coating can obviously improve the resistance of RFS to ultraviolet aging. Results of fatigue load showed that RFS deboned from concrete substrate only when the inner concrete was ruptured by impact force, and spalling would not appeared even though partial damage.Through simulations experiments under current laboratory condition, this paper puts forward the general idea of construction as follows. Fixing the RFS onto the inside of formworks and pouring concrete, and RFS could become a unit with concrete, after removing the formworks, then the construction project was finished. Furthermore, surface resin coating can be used as effectively method to repair the damage appeared.