Abstract
The emergence of Ultra High-Performance Concrete (UHPC) is one of the latest developments in concrete technology. Repairing and rehabilitating damaged structures by applying a thin layer of several centimeters on conventional concrete (with or without reinforcement) has been one of the applications of UHPC. Due to its very small porosity and excellent permeability, UHPC has extremely high durability against the penetration of destructive substances such as water, chloride ions, oxygen, etc. In this work, we investigated the durable effect against external aggressive corrosive substances by coating a 2.5 cm thickness layer of UHPC on conventional concrete. The desired composite concrete consists of a conventional concrete core with a compressive strength of 40 MPa and a coating with a thickness of 2.5 cm of UHPC cover. Then, this concrete went through oxygen penetration, Rapid Chloride Permeability Test (RCPT), and electrical resistance tests. Finally, to verify the results of the durability tests, two sets of comparison reinforced concrete specimens with 5 cm as their covers were exposed to an accelerated corrosion test. It is found that the substitution of a 2.5 cm layer of UHPC instead of the conventional concrete resulted in a 30-times increase in resistance against water penetration, 41 times against chloride ion penetration, 307 times against oxygen penetration, and 8 times in its electrical resistance. Based on corrosion acceleration test results, after 30 days of applying a current with a voltage of 31 volts, the control specimens with a 5 cm cover started to corrode after one week. After 30 days, 47 % corrosion was observed. Even though after 365 days, no signs of corrosion were found in the UHPC-coated specimens.
Published Version
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