Experiment And Application Study Of Polyurethane Sulphoaluminate Cement-based Grouting Materials

The mechanical properties of the grouting material are the key factors that determine the success of the grouting project.Cement materials have high compressive strength and good durability,but they are poor in flexibility.They are mostly used for roadway reinforcement.They are not ideal for roof delamination and crushing reinforcement;organic Polymer materials have strong adhesion,good flexibility,but poor safety.In March 2020,the State Coal Mine Safety Supervision Bureau drafted the "Safety Management Methods for Reactive Polymer Materials Under Coal Mine" to limit and regulate the use of polymer materials.Therefore,the development of inorganic-organic composite materials and the improvement of mechanical properties of cement-type grouting materials through polymer emulsions or rubber powders are of great significance for strengthening broken rock masses,improving the shear resistance of roofs and expanding the application range of cement-based grouting materials.In this paper,the effects of ultra-fine mineral powders and polyurethanes on the mechanical properties of sulphoaluminate cement(SAC)materials are studied,and the composite properties are comprehensively analyzed in terms of setting time,viscosity,injectability,mechanical properties and swelling properties;XRD,SEM/EDS,contact angle test methods,study composite hydration products,micro-morphology and wettability;combined with molecular dynamics simulation technology,studied the mechanical properties of sulphoaluminate cement typical minerals from the perspective of molecular mechanics;Field tests were conducted at Changping Mine to verify the engineering applicability of the materials and optimize the admixture ratio of the materials based on the site conditions.The main conclusions are as follows:(1)The incorporation of ultra-fine mineral powder can increase the compressive strength of 18.7% of the material;different types of water-based polyurethanes have a great difference in the mechanical properties of sulphoaluminate cement,and cationic polyurethanes can significantly improve the tensile strength of the material and resist compression.There is no adverse effect on strength.Anionic and non-ionic polyurethanes have adverse effects on SAC mechanical properties.(2)The addition of the compound admixture makes the initial setting time of the material adjustable from 5min to 60 min,and the final setting time is adjustable from 40 min to 200min;during the pumping period,the viscosity of the slurry is low and the diffusion performance is good;Improved injectability;the addition of polyurethane can improve the flexural strength of the material,especially in the early days,which increased by 29.4%,50.7%,and 33.9% respectively at 1 day,3 days,and 7 days;the addition of bentonite and aluminum powder makes the material slightly Swelling characteristics.(3)XRD phase analysis shows that the addition of polyurethane increases the temperature of the reaction system and the hydration rate is accelerated,but the hydration product has no obvious effect.The observation of microscopic morphology shows that the addition of ultrafine powder improves the compactness of the cement stone and the plastic formed by polyurethane The network structure is embedded in the cement stone,which inhibits the development of microcracks and improves the toughness of the material.Wetting research shows that the contact angle increases and the material changes from hydrophilic to hydrophobic.(4)Molecular dynamics simulations show that polyurethane has good compatibility with SAC;polyurethane improves the elastic modulus and bulk modulus of composite materials;the mechanical properties of composite materials are better than single-component materials;field tests show that the The material can effectively reinforce the roadway side and roof,and the deformation and speed of the roadway are reduced to a safe range.