Experimental Study On Performance Of Mortar And Concrete With High Volume Fly-ash

With the gradual arrival of China's comprehensive construction of a well-off society,the development of the construction industry has gradually reached a peak,resulting in the increasing demand for building materials.As one of the most important raw materials for the construction industry,the annual output of cement increased by 21% from 1.9 billion tons in 2010 to 2.3 billion tons in 2019.The production and consumption of cement in this process is huge.Fly ash as a common industrial waste is widely used in the concrete industry,but the proportion of fly ash in concrete is strictly limited.The research of this topic focuses on improving the strength of concrete with large amount of fly ash.The main research contents are divided into three parts: mortar performance study,ash ash activity study and performance study of concrete with large amount of fly ash.In the performance test of mortar,it is shown that fly ash can reduce the friction between cement particles and improve their performance.Design test,the alkaline arousal other variables involved in the testing process of water-binder ratio,fly ash content,calcium hydroxide content and curing temperature and humidity,through the experimental data show that different dosage of fly ash mortar needed to supplement the amount of calcium hydroxide is different,to improve overall strength one of the biggest group among the activity of fly ash index is 0.5,which further verify the correlation of active index of fly ash and the correctness of the quantitative calculation of alkali content.The contribution of fly ash to strength can be distinguished separately in the study of ash pozzola-activity,which can more intuitively reflect that fly ash does not reduce strength under certain conditions,but makes some contribution to strength.In the relationship between fly ash content and pozzolanic activity,the contribution value of pozzolanic activity to the intensity was first increased,then more moderate,and finally decreased.The contribution of ash pozzolanic activity to the strength was always positive in the alkali activation activity,and the temperature factor and curing age were positively correlated to the strength contribution.In the experimental study of high-content fly ash concrete,the method of low water-binder ratio and low cement content is adopted to prepare the concrete with excellent performance.In the mechanical property test,it is concluded that the high-content fly ash concrete,compared with the ordinary concrete,has higher axial compressive strength and static elastic modulus under the same compressive strength grade.In the curing way of concrete,the humidity environment has some influence on the concrete with large amount of fly ash,and the humidity of about 60% is more suitable for the curing of concrete with high amount of fly ash.