Sea Sand Purification Quality And Its Influence On The Performance Of The Ready-mixed Concrete

Purification of sea sand is a kind of new sand source in the coastal areas of theshortage of natural sand resources. In order to ensure the purification sea sand qualitydoes not affect the durability of reinforced concrete, this paper mainly studies thecharacteristics of sea sand, sea sand purification process and the regular pattern of itsinfluence on sea sand quality; the performance of mixed concrete which compound ofpurification of sea sand and mechanisms sand; sea sand mortar Cl-binding rule andits influencing factors; the rule of steel corrosion in sea sand mortar.First of all, this paper takes samples in the important process of sea sandpurification. According to the regulation of JGJ52-2006, systematic tests of differentsea sand indicators, analyses the results of current sea sand purification process andimproves this process. Secondly, using purified sea sand as main fine aggregate ofconcrete, based on the workability, strength and deformation properties, discuss themixed proportions and the effect of configure concrete by using purify sea sand. Thendesign multiple mortars with different mixing proportion and Cl-content to test theCl-binding ratio, and microscopic observe the samples by using scan electronmicroscope. Lastly, use anodic polarization curve method to test the steel corrosion inthe mortar.The results show that as long as the purification of sea sand follows scientificmethods, it is qualified and it can meet the requirements of concrete application andalso Can be used in the ready-mixed concrete production. The mix sand withpurification of sea sand and the mechanism sand can overcome effectively theperformance of two kinds of sand defects, and further reduce the introduction of thecontent of chlorine ion in concrete. There is an optimal value of the percentage ofpurifying sea sand in the mixed sand and it equals to55%-65%in this paper. Theperformance and mechanical properties of the concrete prepared by the mixed sandwithin the optimal range can fully fulfill the design requirements. The different levelof influence on the Cl-combining ability of mortar from different factors can bestated as: the method of introducing Cl-> the dosage of fly ash and slag> the age> the water-binder ratio> the sand-binder ratio. Comparing the brine mortar and seasand mortar which contents the same Cl-, the rate of chemical combination of Cl-ishigher in brine mortar. And in sea sand mortar, the rate of physics combination of Cl-is higher, the content of free Cl-is lower, the degree of reinforcement corrosion islighter and the corrosion rate is slower. When the content of Cl-is0.030%and themixing proportion of sea sand and mechanisms sand is equal to or less than80:20, theinfluence of the steel corrosion will not change. When the content of Cl-is0.061%,and the mixing proportion of sea sand and mechanisms sand is equal to or less than75:25, the influence of the steel corrosion will not change, too. This paper uses bothdry sand sample preparation and wet sand sample preparation to make sand samplesand then use ion selective electrode method to measure the content of Cl-in the seasand. This paper comprehensive compares the difference of combination rules of Cl-which introduced from sea sand and the ordinary one which doped from chloride salt.And it also compares the difference of the steel corrosion in these two differentsituations.