| Fly ash is the industrial waste produced by the burning of the power plant,which emits hundreds of millions of tons each year,but the utilization rate of fly ash is very low,which has a great impact on the environment.And low water-binder ratio of high performance cement-based materials as a new "green" materials,the applications of active mineral admixture in cement mortar or concrete,on the one hand,reduce the dosage of cement and reduce the cost and reduce environmental pollution,on the other hand also improved the workability of mortar or concrete,physical properties,such as mechanical properties,durability,and reduce the temperature rise.But in the fly ash to replace cement as the cementing material added to the cement or concrete,the early strength is generally low,and the bigger the dosage of fly ash,its early strength decline,the more obvious,which largely limits the application of fly ash.It is not difficult to find out that the activity of fly ash is less than that of high performance cement-based materials.Compared with the cement based materials,the water-based environment and hydration mechanism of low water cement are different than that of high performance cementitious materials.And composition is also different in strength,high water/cement ratio of cement base material strength weak link is the cement stone and interface structure of coarse aggregate and cement stone,and low water-binder ratio of high performance cement base material intensity in the weak link is the strength of coarse aggregate and its chemical composition.Therefore,in order to eliminate the influence of coarse aggregate,this topic is proposed under the condition of low water-binder ratio active excitation of fly ash and fly ash and cement mortar mechanical properties research,based on the activity of fly ash excitation mechanism to explore the mechanism of under low water-binder ratio,selecting Na2S04 as active excitation agent in fly ash and cement mortar strength test,find out the optimum under the different dosage of fly ash excitation agent dosage,make its active gets into full play.The main research results of this paper are as follows:(1)using sodium sulfate as chemical excitation agent,research on low water-binder ratio under alkali excitation intensity of fly ash and cement mortar,can configure the fly ash content is 30%?70%,under the water-binder ratio of 0.24,fly ash and cement mortar 28 days compressive strength more than 59.9MPa,water/cement ratio 0.28,fly ash and cement mortar 28 days compressive strength is greater than 51.9MPa,water/cement ratio 0.32,28 day compressive strength of fly ash cement mortar is more than 48.7 MPa.(2)in the case of low water glue ratio,the incorporation method of alkali activator should be added in proportion to the total amount of fly ash for the alkali activated fly ash-cement mortar.(3)according to the total percentage of fly ash excitation agent to join,the dosage of 0.5%?73%,the compressive strength of moritar increased with the increase of exciting agent content showed a trend of growth before they are flat or declining,flexural strength of mortar with increase with the increase of the dosage of exciting agent,and in different dosage of fly ash and water-binder ratio,there exist an optimal dosage of exciting agent dosage.(4)the strength of fly ash-cement mortar decreases with the increase of fly ash content.Whether or not the activator is added,the strength of fly ash cement mortar is lower than that of pure cement mortar.(5)under the low water-binder ratio,alkali excitation intensity of fly ash and cement mortar mainly by active oxide from fly ash three silica,alumina,etc,the effect of silica and alumina total content is higher,after adding exciting agent,the higher the strength of mortar. |
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