| Because of the unstable composition,the utilization rate of desulfurization gypsum is low,and a large number of it accumulates,causing waste of land resources and harming the environment.Due to its characteristic of enhancing the strength of cementitious system,it can be used in road base or subbase,so as to realize the resource utilization of solid waste and reduce the project cost.In view of the low strength and poor water stability of a large amount of desulfurization gypsum used in road base materials,based on Al2O3-OH-SO4 ternary hydration system,the portland cement inorganic binder was designed to consolidate desulfurization gypsum,and a certain amount of collosol was added.The mechanical properties and water stability of desulfurization gypsum-based inorganic bonding materials were systematically studied through macroscopic mechanical tests.combined with X-ray diffraction analysis（XRD）and scanning electron microscope（SEM）technology,the microstructure and hydration mechanism of desulfurization gypsum based composite cementitious system were revealed.The results showed that:（1）When using cement stable desulfurization gypsum,with the increase of cement dosage,the finer the grain size of desulfurization gypsum-based inorganic bonding materials is,the larger the optimum water content is,and the smaller the maximum dry density is.（2）When collosol is not added,the strength of cement is 4.3 MPa at 10%,4.73MPa at 15%and 5.84 MPa at 20%respectively.With the increase of cement content,the unconfined compressive strength increases gradually under the same mix ratio.（3）On the whole,the mechanical properties of the alloy were enhanced after incorporation of collosol.With the increase of collosol content,the unconfined compressive strength increases first and then decreases.When the cement:desulphurization gypsum=10:90 and collosol content is 0.5%,the compressive strength of 7D increased by 22.8%,and macroscopic intensity showed a trend of decrease.when the collosol content is more than 6%.（4）The water stability of the desulphurization gypsum-based inorganic binder after adding the collosol is improved.When the cement mass ratio is 10%and the collosol content is 0.5%,the softening coefficient is increased by 2.40%and the softening coefficient is 0.94.（5）By means of XRD test and SEM test,analysis the hydration products of desulfurization gypsum-based composite cementitious system with different collosol content were analyzed as short rod-shaped dihydrate gypsum,fibrous calcium silicate（C-S-H）gel and a small amount of needle rod-shaped ettringite（AFt）. |
