Study On The Breakup Mechanism And Modified Materials Of Pisha Sandstone

The breakup characteristics of Pisha Sandstone under the influence of water caused the serious soil erosion in Inner Mongolia ordos area. In order to effectively control the soil and water loss and promote the vegetation recovery in local area, check dams and vegetation sand-fixation need to be combined. However, the complex terrain in this region caused serious traffic inconvenience. Damming materials can not be brought into the construction site massively and economically. To avoid the secondary damage in local environment and use the local materials directly, this paper aimed at finding out the Pisha Sandstone modification method based on the basic physical and chemical characteristics and the breakup mechanism. Pisha Sandstone was successfully modified into a green damming material and high performance materials. They were used in the construction of check dam and other projects. In this paper, the main conclusions were showed as follows:(1) The mineral composition and mineral content were obtained by the characterization and analysis of Pisha Sandstone. It can be seen as a composite of quartz, albite and potassium feldspar and clay cementation minerals which contant montmorillonite. And this paper established the ternary physical structure model of Pisha Sandstone which lay the foundation for the research of Pisha Sandstone modification.(2) Via comprehensive investigation of the breakup and basic properties of Pisha Sandstone, we found that the primary cause of the breakup of Pisha Sandstone is the weak cementing performance and containing montmorillonite which has a powerful expansion with water and lack cementation. The ternary physical structure model and free oxide cement modified method is put forward.(3) The strength mathematical model of Pisha Sandstone is deduced according to the composite material strength theory and soil strength theory. It would be the theoretical foundation of the Pisha Sandstone cement modification. Based on the diffusion of electric double layer theory and cation exchange technology, the expansion of Pisha Sandstone sandstone was efficiently inhibited. And the modified Pisha Sandstone materials which are environmentally friendly and low prices were successfully developed.(4) Based on mineral weathering characteristics of Pisha Sandstone, this paper put forward accelerated weathering and activated modification technology to developed high strength materials and eliminate the expansion. And by accelerating weathering tests confirmed the feasibility of this modification technology. Finally, successfully developed high strength modified material. The maximum compressive strength can reach 46 MPa, softening coefficient can reach 0.95. The reaction products of hydrated were calcium silicate, hydrated silicon calcium aluminate, zeolite and Si-Al gel (gepolymer).(5) The mixture ratio design method of modified materials is deduced by useing absolute volume method and linear fitting method. Based on accelerated weathering and activation modified method, the fluidity of modified material was greatly improved by the way of high temperature calcination treatment and adding suitable amount surfactant. And this paper successfully developed modified cementitious materials of Pisha Sandstone.(6) Based on accelerated weathering and activated modification technology, the modification bricks were developed to solve the problem of lacking building brick in local area. And the demonstrative project of Pisha Sandstone modification check dam was established in Inner Mongolia Ordos area.