Study On Properties Of Fly Ash Geopolymer Reinforced By Multiple Solid Wastes And Its Treated Material Properties

In order to solve the problems of low strength and slow forming of Fly Ash Geopolymer(FAG)under normal temperature maintenance,three kinds of industrial solid wastes such as calcium carbide slag,desulfurization gypsum and steel slag are selected to synergistically enhance FAG,and multi solid wastes synergistically enhance FAG as inorganic binder to prepare stable gravel material.The physical and chemical properties of solid waste raw materials were analyzed,and the macro properties(fluidity,setting time and compressive strength)of three kinds of solid waste single reinforced FAG were carried out.The strengthening mechanism was analyzed by means of hydration heat measurement,phase analysis and scanning electron microscope,The proportion of FAG reinforced by multiple solid wastes was optimized by response surface analysis,and the stabilized macadam material of FAG reinforced by multiple solid wastes was prepared,and its road performance was analyzed.The main results are as follows:(1)Calcium carbide slag will reduce the fluidity of FAG slurry,shorten the setting time of FAG,and effectively enhance the compressive strength of FAG.When the content is 6%,the 7d and 28d compressive strength of FAG can reach 17.2MPa and 20.3MPa at most;calcium carbide slag promotes the geological polymerization by enhancing the alkaline environment and providing calcareous components,forming hydrated products mainly composed of calcium silicate hydrate and hydrated aluminosilicate gel.(2)Desulfurized gypsum can significantly shorten the setting time of FAG and effectively improve the compressive strength of FAG,especially the early compressive strength.When the content is 3%,its 7d and 28d compressive strength reaches the maximum,which are 15.6 MPa and 17.6 MPa respectively,but too much desulfurized gypsum will lead to a sudden drop in fluidity;Desulfurized gypsum promotes the geological polymerization by providing calcium components and sulfate excitation effect,and produces hydrated products mainly composed of C-S-H,C-A-S-H,N-A-S-H hydrated gel and AFt crystal.(3)Steel slag can reduce the fluidity and shorten the setting time of FAG,but it has little effect compared with calcium carbide slag and desulfurization gypsum.When the content is 30%,the 7d and 28d compressive strength of steel slag reinforced FAG reaches the maximum,which are 19.3 MPa and 24.9 MPa respectively;Steel slag promotes geological polymerization by providing more calcium components and aluminosilicate components,and produces hydrated products mainly composed of C-S-H,C-A-S-H and N-A-S-H gel.(4)The optimized ratio of multi solid waste synergistic Reinforced Fly Ash Geopolymer is 6.34%of calcium carbide slag,1.6%of desulfurization gypsum and 29.47%of steel slag.The 7d compressive strength and 28d compressive strength can reach 18.1mpa and 29.92MPa;When the content of inorganic binder is in the range of 4.5%-6%,the 7d unconfined compressive strength of stabilized macadam material can meet the requirements of most grade pavement base materials,and has good water stability.However,the increase of the content of inorganic binder will reduce the resistance of stabilized macadam material to drying shrinkage cracks.