Adaptability Experimental Research Of The Filling Pile In Strong Sulphate Corrosive Environment

Compared to precast pile,the filling pile exists the problems of making contact with around the water and soil medium when the concrete of pile is poured on-site, difficult to normal vibration and conservation, and unhardening,which are largely limited the use of filling pile.Therefore, the current national standard "code for anticorrosion design of industrial constructions" specifies that bore concrete pile shoulds not be used in highly corrosive environment,but precast pile can be used.At present,the ground water in many areas of china,contains large amounts of sulphate ions, but a large numbers of filling piles are used in the above regions. The problem of filling piles can or not be used in the above environment, has become the focus of civil engineering realm.It is urgent that the problem be solved,but has not been solved all along.The key influence factor of the use of filling pile in strong corrosive environment is the problem of reducing corrosion resistance cased by concretes under unhardened conditions make contact with the corrosive medium.That is to say, the problem of corrosion resistance about fresh concrete.So far,no research date about sulphate resistance of fresh concrete has been found at home.There is only a very few research date about sulphate resistance of fresh concrete in the abroad.In order to compare the sulphate resistance of filling pile and precast pile in strong sulphate corrosive environment.In this paper,the tests of full immersion on fresh concrete and standard curing concrete with different concrete mix ratios of ten in Na2SO4 solution(50g/L) are performed,and using corrosive coefficient of compression strength and rate of mass change as evaluation indicators. The study carried out a total of 870 specimens, which lasted 270 days,and draws the following main conclusions:(1) Within 270 days of erosion age,the sulphate resistance of fresh concrete and standard curing concrete follows the rules of first increase and then decrease,but the fresh concrete still has a high resistance to sulfate attack under conditions of different anti-corrosion measures.(2) The resistance to sulfate attack of fresh concrete and standard curing concrete bears a relation to the use of anti-corrosion measures:the lower the anti-corrosion measures are,the slower the corrosion rate of fresh concrete and the faster the corrosion rate of standard curing concrete will be;The higher the anti-corrosion measures are,the faster the corrosion rate of fresh concrete and the slower the corrosion rate of standard curing concrete will be.(3) The incorporation of appropriate amount of fly ash can significantly improve the resistance to sulfate attack of fresh concrete. The lower the anti-corrosion measures are and the worse the erosion environment is, the generally higher the volume of fly ash and the more significantly the effect is.(4) In extreme sulphate corrosive environment,sulphate-resistant cement can improve the resistance to sulfate attack of standard curing concrete, but the effect is not significant.(5)Extending the trial erosion age,to be helpful to the more profound understanding of the basic norms about the resistance to sulfate attack of fresh concrete.