Study On Physical And Mechanical Properties Of Super Absorbent Polymer (SAP) Filling Material In Goaf

When highway engineering passes through the goaf,under the action of roadbed and traffic load,the underlying goaf appears "activated",and the residual deformation of the ground surface is too large,causing a series of damages to the road.Goaf filling is one of the important methods to effectively solve such problems.In view of the high cost of filling materials,unattached filling,serious underground pollution and other problems,this paper uses loess,cement and super absorbent polymer(SAP)to prepare SAP filling materials,and conducts laboratory test to study its filling feasibility.The analysis focuses on the influence of different factors on the working performance,mechanical property and expansion performance of SAP filling materials.The research on raw materials and dual materials was carried out.First,the basic performance indicators of the raw materials were tested and researched to understand the basic performance of the raw materials.The loess slurry,cement slurry and their mixed slurry were centrifuged to obtain the same ions as the original slurry.Environmental centrifugal fluid,and test the water absorption of SAP in the centrifugal fluid to represent the water absorption of SAP in the real slurry,study the water absorption capacity of SAP in the slurry,and provide a reference for the SAP content.Then,through the slump and strength tests of different proportions of loess and cement,the water-soil ratio and cement content that meet the slump and strength requirements are obtained.Finally,the slump test of loess and SAP,cement and SAP was carried out to study the influence of SAP on the slump,and a suitable SAP content range was obtained.Based on the research results of raw materials and bi-material tests,the specific levels of the three proportioning factors of SAP filling material water-soil ratio,cement content,and SAP content were determined,and the three factors were studied through slump,fluidity,and bleeding rate tests.The influence of these factors on the working performance of SAP filling materials.The influence of three factors on the strength and swelling of SAP filling material was studied through strength test,microscopic scanning of electron microscope and measurement of expansion rate.Then according to the filling index requirements of the corresponding performance,the optimal mix ratio that meets the conditions is gradually screened.Finally,from a long-term perspective,the corrosion resistance of SAP filling materials to alkaline solutions and different salt solutions under long-term conditions is studied.According to the quality and strength changes of the filling body in different corrosive solutions,the anti-erosion ability of different ions is obtained.And from the shrinkage and temperature shrinkage tests,the relationship between the shrinkage strain of the filling material and the age and water loss rate and the temperature sensitivity range are obtained.Based on the above research,a new type of filling material with low cement,swelling and no pollution was obtained,and it provides a new way for the application of SAP in engineering.