The Influence Of Fly Ash Content On Performance Of Hydraulic Mass Concrete

There are many advantages for fly ash on low cost,wide source and so on.By mixed with fly ash in the concrete,not only the amount of cement and fine aggregate can be saved,the water consumption can be reduced,but also the concrete mixture workability can be improved,concrete plasticity can be reinforced,the hydration heat can be reduce,and the concrete impermeability can be improved.At the same time,accumulation and dust pollution of fly ash can also be solved,environmental benefits can be achieved,and land resources can be saved.By researching effect of fly ash content on the performance of cement hydration heat,concrete adiabatic temperature rise,concrete compressive strength,concrete tensile strength,concrete shrinkage and so on,the influence of fly ash on crack of hydraulic mass concrete is further explained.Experimental results show that the total cement hydration heat can be greatly reduced with more than 30%fly ash;the influence of different types of admixture on cement hydration heat has little change within 30%fly ash content;the early strength can be reduced when fly ash and admixture are "double mixed",in particular,the strength of the 7 days ago is reduced significantly,and the magnitude of the decrease is also increased with the increase of the content of fly ash;when the concrete is mixed with some fly ash,and in the range of the test fly ash content,the concrete permeability is proportional to amount of fly ash;concrete shrinkage is closely related to admixture type and concrete strength grade,concrete shrinkage can reduce in a certain extent by mixed fly ash,and the magnitude of decrease is related to amount of fly ash;when concrete strength grade is constant,concrete adiabatic temperature rise can be improved by adding appropriate amount of fly ash.Finally combined with practical application and test in Suizhong Houshan Reservoir engineering,the mixing amount of fly ash is respectively 35%,40%and 55%for the concrete C9030W6F200,C9020W6F100 and C9015 W2F50.At present,the main body of the concrete dam is finished,and no obvious cracks are found.Therefore,concrete performance can be improved by mixing a certain amount of fly ash,and the role of controlling concrete crack is played.