Experimental Study On The Properties Of New Polyurethane Cement Earth-rock Grouting Material

The leakage has always been one of the main dangerous problems of earth-rock dams,which is directly related to the safety and investment of water conservancy projects.Grouting is one of the main technologies to solve the leakage problem of earth-rock dams.In this paper,a new type of polyurethane cement mortar grouting material is developed using new polyurethane polymer materials and cement,and the properties of its slurry setting time,fluidity,compressive strength,flexural strength,freeze-thaw resistance and other properties are investigated.Moreover,the properties of soil body impregnated with the proposed polyurethane cement material are investigated,which include unconfined compressive strength,water stability and freeze-thaw resistance.In addition,the micro-structures of new polyurethane cement material and new polyurethane cement material-soil improvement were observed and analyzed with the method of a scanning electron microscope.The main research contents and conclusions are as follows:1)The main properties of the new polyurethane cement material and ordinary cement material were investigated.The experimental results showed that under standard curing conditions,the compressive strength,flexural strength and the setting time were significantly reduced when the new polyurethane cement material was compared with ordinary cement material at the same water-cement ratio.In addition,the compressive and flexural strength of the specimens under the maintenance conditions of the simulated field environment also showed the same rules as the standard maintenance conditions.The micro-structures of the new polyurethane cement material and the ordinary cement material were characterized with the Scanning electron microscope(SEM)method.The experimental results indicate that the polyurethane in the new polyurethane cement slurry formed more fibrous substances in the cement slurry.The fibrous substances could fill pores and cracks,reduce pore structure connectivity,and increase the slurry density.2)The main properties of the new polyurethane cement material-soil specimen under normal temperature curing conditions were investigated.The experimental results showed that the new polyurethane material had a significant improvement in the compressive strength of the soil.The cement materials could reduce the compressive strength of the new polyurethane material-soil modified body in the middle and later stages,but it could significantly improve the early compressive strength.The unconfinedcompressive strength of the new polyurethane cement material-soil was significantly improved with the increase in cement content and the polyurethane concentration.Simultaneously,the water stability of the soil body was improved.The main properties of the new polyurethane cement material-soil improvement under simulated field environment maintenance conditions were investigated.The experimental results showed that the new polyurethane material had significantly improved the compressive strength of soil.The compressive strength of new polyurethane cement material-soil higher than that of the new type of polyurethane material-soil modified body.The microstructure of the new polyurethane cement material-soil improvement was characterized by Scanning electron microscope(SEM)modern analysis technology.The experimental results showed that the membranous substance was formed in the new polyurethane cement material-soil improvement.The compressive strength was improved and its cementing performance can be exerted.3)The freeze-thaw resistance of the new polyurethane cement material specimens and the new polyurethane cement material-soil improvement was investigated.The experimental results showed that the new polyurethane material had significantly improved the freeze-thaw resistance performance of the cement paste.The mass and the strength loss rate of the new polyurethane cement material were reduced with the increasing in the polyurethane concentration.The freeze-thaw resistance performance of the soil was significantly improved.The greater the concentration of the new polyurethane,the better the freeze-thaw resistance of the soil improvement body.