Application Of Grade Ⅲ Fly Ash For C30 Concrete

In recent years, with interdisciplinary research merging and promoting, research and practical on new building materials are developing in a rapid rate.The functional properties of different mineral admixtures are mixed in concrete have been explorated and practiced, also it has become an important research trend. Grade Ⅲ fly ash is the main industrial scrap from the electric field, been called "artificial sandstorm", grade Ⅲ fly ash has a huge production, not only occupy the land and impact environment, also bring the economic pressure on some companies, combining with the market research and analysis, learning from the results of previous studies, defining the study named the research of the C30 concrete mixed grade Ⅲ fly ash.In order to make use of grade Ⅲ fly ash effectively and fully, to C30 concrete that used commonly as the research object, in the test, with the grade Ⅰ fly ash as the basis, sand coarse aggregate ratio, pumping agent dosage, equivalent efficiency of grade Ⅲ fly ash etc. as the factors, the the scheme L9(34) orthogonal test and single factor test were designed. Then, action law of the basis and original grade Ⅲ fly ash influence on the workability and compressive strength of concrete was contrasted and studied, also mechanism, possibility,and reasonable dosage are studied. The results shows that:the compressive strength of concrete mixed grade Ⅲ fly ash decreases with the increase of the sand coarse aggregate ratio and increases at first then decreases with the increase of equivalent efficiency and the quantity of pumping agent, and the optimal equivalent efficiency is 100 percent.(reasonable value about 80%). The best combination is:sand coarse aggregate ratio36%, pumping agent dosage2.8%, equivalent efficiency 1.0. The main factors influencing the strength of concrete is fly ash replacement rate and sand coarse aggregate ratio.On the basic of compressive strength of concrete,Using the grade Ⅲ fly ash replacement rate and magnesium slag content as the factors the mixed test scheme U12(6,4) text was designed, research on the strength and carbonization rules of concrete by experiment in two factors coupling conditions was designed. The results were dealed by using least squares, building the nonlinear regression mathematical model to exploring the action law of strength and carbonization depth for concrete.The results shows that:The effect of grade Ⅲ fly ash replacement rate on strength of concrete is negative, of magnesium slag content when not greater than 49% is positive, the coupling effect of fly ash and magnesium slag is positive, reasonable combination of grade Ⅲ fly ash and magnesium slag is f=36%, m=5%.In carbonization test,the main factors influencing the carbonization of concrete is fly ash replacement rate, followed by magnesium slag content. The effect of grade Ⅲ fly ash replacement rate on carbonization of concrete is positive, of magnesium slag content when not greater than 33.8% is negative, the coupling effect of fly ash and magnesium slag is negative. Also nhibiting the growth of carbonation depth.Grade Ⅲ fly ash can made qualified concrete with workability, strength and carbonation.