Study On The Activity Analysis Method Of Composite Admixture Of Concrete

The high activity mineral admixtures obtained by a certain quality control andpreparation techniques, which can be used to reduce cost and improve thedurability and workability of concrete. Research on method of analyzing activity ofmineral admixtures shows important engineering reference value for mineraladmixtures used in concrete. Several accelerate tests were used to accelerate thereaction of the active ingredient compound of mineral admixture. These testsinclude measuring the the activity ratio, active silica and alumina percentage, andelectrical conductivity of mineral admixtures, analyze the relationship between theactivity rate, active silica and alumina percentage, electrical conductivity and thestandard mortar activity index. What the main research carried out and the resultsof this paper are as follows:(1) The species and the curing age of admixture will affect it’s active index.The activity index method is used to characterize the activity of admixture, theresult shows that when one of steel slag powder (SS), fly ash (FA), granulated blastfurnace slag powder (GS) was single doped, the order of activity is GS>FA>SSwith curing age of7days and28days.(2) Activity index method is used to characterize the activity of compoundadmixtures. The result shows that when SS is mixed with FA, silica fume (SF) andGS separately, its early activity and activity in28days are higher than what has SSonly. When the FA is mixed with SS and GS respectively, its early activity andactivity in28days are higher than what has FA only.(3) The result of active factor shows that the active factor of mineraladmixtures will be changed with its type and age. When SS, GS, FA and SF aremixed with each other in different proportion separately, its active factor in7daysis lower than its in28days, it turns out that the compound mineral admixtures haspositive effect on its long-term strength, whereas has negative effect on earlystrength.(4) The activity ratio Ka can be used to analyse the acativity of some binarymixed mineral admixtures such as SS-GS, SS-SF, FA-GS. It also turns out that theactive silica and alumina percentage of SS-GS, SS-SF, SS-FA, FA-GS, FA-SFhas good correlation with theirs activity index in28days.(5) Conductivity method is suitable for analysing the acativity of compositepowder. But due to the effect of calcium oxide content in mineral admixtures, conductivity method applies to estimating the activities of mineral admixturesapproximately only. The method has some limitations. But when operated, it maybe simple and quick.