Research About The Detection Method Of The Content Of Chlorine Ion In The Sea Sand

In the past few decades, many countries in the world have made development of urbanization positively, the shortage of river sand resource has been urgent. The abundant and cheap sea sand resource which is convenient to mine has gradually become the focus of various countries. However in the process of the sand application,if we can not strictly control the the chlorine ion content in the sea sand for the building, it will cause corrosion of the reinforced concrete in the building and ultimately affect the service life of the building after a period of time because of the high content of chlorine ion in sand. But at present all standards in China used the chloride ion’s content detection method in GB/T 14684-2011 “sand for construction”,this method has many problem and can not completely detect the content of chloride ion in sea sand:chloride ion’s content in sea sand after second immersion is about 50%of the value of the first precipitation and the detection of chloride ion’s in wet sand sample is 20-30% more than the dry sand, and with the extension of the sea sand immersion time the value of detection also will rise slowly by taking the national standard method. It indicate that the national standard method has problem.It is necessary to research the new chloride ion’s content detection method which is applicable to sea sand.First this paper obtains the representative sea sand in different area by taking reasonable mining and sampling method and the influence of the experimental condition for value of chloride ion’s detection in sea sand has been researched by taking single factor method, concluding that improving the heating temperature and extending the heating time will promote chloride’s dissolution and affect the value of detection, when the heating temperature reached 80℃ and heating time reached 60 min, the value of chlorine ion’s detection reaches the maximum; and sampling quality and preparation of wet or dry sand sample will not have impact on the result. And change the method for detection of the content of chloride ion in the sea sand:it will influence the the end point of titration because of the high content of the pH value,sulfide and sulfate in the sand, so add the HNO3 and H2O2 to eliminate the effect in the titration process. And finally propose a new method for the detection of the content of chloride ion in the sea sand:put the solution of the sea sand in a water-bath and heat it from room temperature to 80℃ and keep it for 1h, change the filtrate to neutral and add the HNO3 and H2O2 properly,then take potassium chromate indicator silver nitrate titration method to determine the solution.Then identified the new method has repeatability and stability by taking repeated trials and detect chloride ion content in multiple sand by taking new method,national standard method and American method, the result show that the chlorine ion content measured by new method is 1-2 times the national standard method,and new method’s error has smaller than American method. And it found that the detection value of chloride ion in sea sand after second immersion can be ignored by analysing the chlorine ion precipitation in the second immersion after new method tested,indicating the new method is more accurate.Then compared new method with national standard method for the chlorine ion precipitation in the concrete alkaline environment, it found that the new method is more applicative than the national standard method.At the end making the analysis of the reason why testing conditions can influence detection of chloride ion, it found that the content of total organic carbon of purified sea sand solution by using the new method is higher than the national standard method, it is concluded that the sand coated with amounts of organic material which make the chloride ion in sea sand being in stable state, and the pretreatment of the new method can enable organic and chlorine ion dissolved,indicating that changing the test condition by the new method can destroy the steady state of the sea sand to dissolve the chlorine ion.