Durability Research Of Reactive Powder Concrete In Marine Environment

Concrete structures are prone to be corroded in the marine environment. In the past few years, study on the durability of reactive powder concrete (RPC) has been the focus in this area. Because of the high strength and durability of RPC, the trend is that RPC is to be applied to the marine engineering in the future. Therefore this paper mainly study on the durability of RPC in marine environment, these studies provide the reference information for the extensive application of RPC in marine engineering. The main content is as follows.According to the closing packing theory, by using the concept of liquid limit in soil mechanics, the liquid limit theory is used for proportion design of RPC. Strength test confirmed that application of liquid limit in mixing proportion design of RPC is feasible.Permeability tests were finished. The test results show that with 2.2MPa of pressure to the RPC, the average depth of the chloride ion diffusion was 8-10mm. Fitting a chloride ion concentration curve equation at certain depth can predict the percentage concentration of chloride ion at certain depth. Based on the modified Second Fick's Law, and to describe the chloride ion diffusion within the RPC, RPC's durability lives in chloride ion penetration were predicted.Rapid freeze-thaw experiments were conducted parallelly in water and seawater. The test results show that After 500 freezing-thawing cycles, the mass loss of RPC is less than 1%, and the surfaces of the specimens were damaged slightly, and the relative dynamic elastic modulus are not less than 80% of those before. After 400 freezing-thawing cycles, relative dynamic elastic modulus in seawater decreases faster than those in water. This paper studied on the spread of chloride ion after different freeze-thaw cycles. Research indicates that the concentration of chloride ion in certain depth becomes larger and larger with the increase of the number of freeze-thaw cycles. The chloride diffusion coefficient increases with the raise of freeze-thaw cycles. The life prediction model of RPC frost resistance was established. The life of RPC frost resistance was predicted with Freezing-thawing of water and seawater respectively. The results show that RPC's life in sea water is 8-10 years shorter than in water. A couple of factors can increase the frost resistance of concrete.Flux tests of RPC were finished, the maximum electric fluxes were less than 30 Coulomb, and 1-2 orders smaller than ordinary concrete. Therefore the high durability of RPC can be seen.Through experimental research, to the RPC durability in the marine environment has a preliminary understanding and the RPC's application in ocean engineering provides a theoretical basis.