Effect Of Cement Fineness And Content Of Alkali And Sulfur Of Cement On The Development Of Concrete Strength

Concrete structures are used to withstand various forces. Strength is the mostimportant mechanical properties of concrete. The performances of concrete in projects,such as impermeability and frost resistance often have a close relationship with thestrength of concrete. In general, the higher the concrete strength, its compactness andability to resist outside erosion is better. However, when strength is higher, the concretehas a more shrinkage, brittle and is easy to crack. Therefore, the strength is usually usedto assess and control the quality of the concrete.Cement is the active ingredient of concrete, which has a direct effect to theconcrete strength. The influence of cement on the concrete depends on the cementfineness and composition. At present, demand for cement strength, leading to more andmore high strength and early strength component of cement specific surface area andheat of hydration are increasing. Crack resistance and durability is getting worse, thelate strength growth rate of concrete is reduction or even retraction. It is necessaryto pay a close attention to the effect of cement fineness and composition on the strengthof concrete, particularly the late strength development.With increasing the specific surface of cement, the cement hydration rate is fasterand the early strength is higher, but the latter strength may be reduced. In theexperiment, we study the effect of cement with four kinds of specific surface area on thedevelopment of concrete strength. The results showed that: with the increase of cementfineness, the early strength of concrete is higher and the growth rate of the late strength.is reduce. With the growth of the age, the strength of concrete is to stabilize, no longergrowing, the concrete strength which has the smallest cement fineness has been growing,and its late strength has caught up with some fine cements.In addition to the cement fineness, the concretemix and curing of concrete also have important implications for the strength of concrete.With the change of concrete mix proportion and curing method, the effect ofcement fineness on the strength of concrete is also likely to change. In the experiment,we study the effect of cement fineness on the development of concrete strength, whenthe concrete water-cement ratio changing. The results show that when the water-cementratio becomes smaller, the concrete strength increases, but the rough cement has agreater increase on the concrete strength. Experiment also study the effect of cement fineness on the development of concrete strength, when the slag and fly ash contentchanging. The results show that it will reduce the strength of concrete mixed with flyash or slag. slag content has a greater effect to the development of concrete strengthwhose cement particles is rough, and the fly ash content has a greater effect to thedevelopment of concrete strength whose cement particles is fine. In addition, bychanging the concrete curing to study the effect of cement fineness on the developmentof concrete strength. The results showed that the concrete strength under standardcuring is the highest, and then the outdoor natural curing, the minimum is dry indoorcuring. under the standard curing method, the concrete strength of the four kinds ofcement with different fineness increased with the age growing, under the outdoor naturecuring and indoor dry curing method,the concrete strength of the three kinds of cementwith the larger surface area are no longer growing after180d. rather than the cement ofsurface area260m2/kg whose concrete strength is still continue to grow. In a relativelyharsh environment, the strength of the coarse particles of cement is superior to the fineparticles of cement..Alkali and sulfate are the minor component of the cement, but the impaction ofthe development of concrete strength can not be ignored. By changing the contentof NaOH and gypsum to study the effect of cement fineness on the development ofconcrete strength. The results showed that with the increase of the NaOH content ofcement, concrete strength is reduced. More the NaOH content of cement, the moreunfavorable to the growth of medium and long-term strength of concrete of the finercement; The increasing of the gypsum content of cement can reduce the early strengthof concrete which cement particles is coarse and less impact on the medium-andlong-term strength. For the finer cement, the effect of gypsum content on the early andlate strength of concrete is not large. The gypsum can reduce the shrinkage of theconcrete. When the gypsum content changing, the concretes with different fineness ofcement show significant differences in shrinkage behavior.Through the above research, this paper studies the effect of the cement finenessand composition on the development of concrete strength,in order to provide atechnical basis for the upper limit of the cement fineness control and revise of relatedstandards.