Research On Performance Of Composite Admixture

First of all,this article analyses the unreasonableness of the using same quality to wplace cement thesting composUe mineral admixtures activity index practices in theory, as we called the different composite mineral admixl;ures duethe apparent denshy variation,the mortar volume quke different incorporation of the same quality mineral admixtures,so it can not be an objective assessment of the activity index admixture, affecting the composke mineral admixUithformulation of relevant norms,Therefore, the proposed volume insthad of cement mettiod for evaluation of composke admixture activity index. Through a lot of trial sthdies,we confirmed that the volume insthad of the activity index standard deviation of cement measured by the composite admixthre is far lessthan the qualky insthad of measufid activity index standard deviation As a result,it verify the volume insthad of cement method for evaluation of composithadmixluie activity index was the cement quality ahernative method is more stable, more scientific and rational. And further experimental verification of t:he composke admixture volume inst:ead of 50% of the cement volume measured the composite admixture activity index is desirable.The experimental conditions once again confirmed that the admixUire Admixed compthhensive performance than single-doped performance, Fly ash and slag complex doped th produce "super-duplicated effect’’. Although the incorporation of the admixthre of the compound may reduce the early strength ofthe cementitious material, by it can improve the late strength of the cementitious mathrial, and also can reduce the drying shrinkage of the specimen.Secondly, this article compared the excited composUe prepared by admixUiie concieth mixing performance by simple mixing withthe grilling excitation method. Such as performance, mechanical properties and frost resistance, impermeability and volume shrinkage. The test results show that theny ash and ground granulated slag mixed with a ratio of 2:1,and add a small amount of gypsum and sodium sulfate powder grinding to inspire cement and composite admixture for 20 min, general composite cement admixtures to replace 40% of cases making 28 d concrete mechanics performance and durability index far more than ordinary concrete and blank sample simple mixing of concrete legal system. At age 28d grinding excitation specimen compressive strength is 32.9MPa, and simple mixture specimens for compressive strength 29.5MPa, ordinary blank sample specimen of concrete compressive strength is 30.7MPa. At age 60d, grinding specimen strength is 43.8MPa, exceeding the simple mixed sample concrete strength by about 14%. So through experiments with compound admixtures to replace 40% of cement, and by the grinding method into concrete can not only reduce the construction cost of concrete, at the same time it also can effectively improve the concrete compressive strength, frost resistance, impermeability and shrinkage performance in later period.Finally, this article also illustrates that by observation structure of the cement mortar specimen obtained by above method under scanning electron microscope, microscopically justifying the joining of composite admixture can greatly increase the compactness of cement, reducing the porosity and improve the microstructure of internal concrete.