| A large number of solid wastes have been produced in China and even in the world,such as granulated blast furnace slag,fly ash,desulfurized gypsum and steel slag.With the development of economy,the amount of solid waste increases rapidly.Placing these solid waste will not only occupy a lot of land area,but also damage the ecological environment.Slag,fly ash,steel slag and other solid wastes have certain potential activity,which can be activated by alkali activator to prepare alkali activated cementitious materials(AACM).In the experiment,slag,fly ash and alkali activator are used as the main raw materials.Based on the experiment of cement sand and concrete,through the test method of controlling variables,the influence of activator type and dosage,the ratio of slag to fly ash and the ratio of water to binder on the performance is discussed.Combined with the frost rule,the scheme of alkali activated cementitious material is optimized;through alkali activated cementitious material and water reducing,the scheme of alkali activated cementitious material is optimized Study on the adaptability of the agent,optimize the water reducing agent;prepare the concrete through the selected alkali activated cementitious material,test its mechanical properties and durability,analyze the phase composition and micro morphology of the hydration products of the alkali activated cementitious material by using the X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS);through the use of value engineering theory,different mix proportion schemes The value of the prepared concrete is analyzed,and finally the high value,that is,the high cost-effective alkali activated cementitious material mix scheme is selected.The following conclusions are drawn:(1)Based on the strength test of mortar and concrete,the optimal alkali excitation scheme is 10% P·O52.5 cement mixed with 15% by-product gypsum;10% P·O52.5 cement mixed with 4% chloride;4% hydroxide mixed with 4% carbonate.(2)The alkali excitation system is hydroxide + inorganic salt.After full curing,except for some schemes,there is no obvious frost phenomenon,and the strength loss is less than10%.(3)When the alkali excitation system is P · O52.5 cement + inorganic salt,the polycarboxylic acid high-performance water reducer has the best water reducing effect and can greatly improve the fluidity;the melamine type water reducer has the second best water reducing effect;when the alkali excitation system is hydroxide + inorganic salt,the naphthalene type water reducer has the best water reducing effect.(4)When 10% P · O52.5 cement is mixed with 15% by-product gypsum and 4%hydroxide is mixed with 4% carbonate,the overall performance of the prepared alkali activated cementitious material concrete is better,which can be used to prepare concrete with higher strength grade;when 10% P · O52.5 cement is mixed with 4% chloride,the overall performance is slightly worse,which can be used to prepare concrete with relative strength grade Lower concrete.(5)A large number of gels were produced after hydration reaction of alkali activated10% P · O52.5 cement with 15% product gypsum and 4% hydroxides with 4% carbonates.The presence of gel was the main reason for the strength of the colloids,and the diffraction peaks in the XRD map mainly correspond to minerals such as calcium carbonate and zeolites.(6)When 4% hydroxide and 4% carbonate are mixed in alkali excitation scheme,slag powder: fly ash = 7:3,water binder ratio is 0.34,and 1.2% of the total amount of slag powder and fly ash is used in water reducing agent,the value of the alkali excitation cementitious material concrete prepared under this scheme is the highest and the cost performance is the best,which is the final scheme of alkali excitation cementitious material proportion;When10% P·O52.5 cement is compounded with 15% by-product gypsum,slag powder / fly ash =8:2,water binder ratio is 0.3,and water reducer takes 3.0% of the total amount of slag powder and fly ash. |
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