Study On The Mixture Ratio Optimization And The Properties Of Slag And Regenerated Micro Powder Based The Alkali Activated Cementitious Materials

With the rapid development of society,more and more construction waste and industrial waste are produced.It is a problem to be solved to deal with construction waste and industrial waste reasonably.Recycled fine powder as construction waste treatment particle size less than 0.075 mm extremely low utilization of powder,granulated blast furnace slag powder as a by-product of blast furnace ironmaking,these two kinds of powder have a certain gelation under the action of Alkali excitation,it is possible to use it as a cementitious material instead of cement.In this paper,recycled micro-powder was prepared by mixing waste red brick powder and waste concrete powder in the proportion of 2:1.Firstly,the basic properties of recycled micro-powder and slag powder were determined,such as density,specific surface area and activity index.The relationship between the activity of regenerated micro powder and specific surface area was determined.The Alkali activator system of PO52.5 cement + inorganic salt and the Alkali activator system of sodium hydroxide + inorganic salt were selected,the ratio of slag powder to recycled fine powder is 1:1,the ratio of water to binder is 0.5,and the inorganic salts are selected as GFD gypsum,sodium carbonate,sodium sulfate,calcium chloride and sodium metasilicate pentahydrate,the two alkali-activated cementitious materials with the highest compressive strength of concrete cube under two systems were determined by the experiment of concrete,and the ratio of slag powder to regenerated micro-powder and water-binder ratio were changed,.Finally,the alkali-activated cementitious materials of the two systems were determined,the micro structure and structure of the hydration products were analyzed,and the durability of concrete was studied.The results show that the recycled micro powder contains a lot of silicon dioxide and alumina,and has certain activity,and the activity index increases with the increase of the specific surface area,finally,under the Alkali activator system of PO52.5 cement + inorganic salt,the content of PO52.5 cement is 10%,the content ofGFD gypsum is 15%,the content of slag powder and regenerated micro-powder is8:2,the water-binder ratio is 0.3,the content of polycarboxylate high performance water reducer is 2.6%;In the Alkali activator system of sodium hydroxide +inorganic salt,the content of sodium hydroxide is 4%,the content ofcarbonateis 3%,the content of slag powder is 9:1,the ratio of water to binder is 0.34,and the content of naphthalene is 1.2%,The hydration products of the two alkali-activated cementitious materials were mainly composed of C-S-H and C-A-S-H gels with compact structure.In this paper,the durability of concrete in alkali-activated cementitious materials under two systems is studied,including sulfate resistance,frost resistance and impermeability,the concrete of alkali-activated cementitious materials in both systems has good frost resistance,impermeability and sulfate resistance.