Field Test Method of the Resistance to Harmful Substances Intrusion of In-Service Marine Concrete Structures

The marine environment is one of the harshest service environments for concrete structures. Due to improper design, construction and maintenance, serious durability problems often occur. Most durability issues are related to the ingression of harmful substances into concrete, so it is very meaningful to evaluate the anti-intrusion ability of concrete. An in-situ transport parameter test method is developed based on AC impedance spectroscopy technology for in-service marine concrete structures. By using this method, the chloride ion diffusion coefficient of near-surface concrete can be quickly obtained. The test results of in-service breakwater structures show that after six years of service, concrete with cement-based permeable crystallization materials exhibits very high resistance to harmful substances; the addition of magnesium oxide (MgO) expansion agent can also make the concrete denser and the porosity of near-surface concrete can be effectively reduced through reasonable use of fly ash. The above results are confirmed by the widely used standard method NT Build 492, and also demonstrate the reliability of the proposed field test method. The proposed test method has a good theoretical foundation and good repeatability. Besides, it is non-destructive and cost-effective.