Research And Application Of Acrylamide In Situ Polymerization Modified Sulfoaluminate Grouting

In situ polymerization modification toughening is a new way to enhance the toughness structure of sulfoaluminate cement-based inorganic grouting materials at this stage.In this paper,relying on the National Key R&D Program Project(2017YFC0603004)"Key Materials and Technologies for Modification of Rock Surrounding Kilometer Deep Shaft Roadway",we used ultrafine sulfo-aluminate cement-based grouting materials as raw materials and focused on the influence of basic properties of sulfo-aluminate grouting materials(SCGM).Acrylamide in-situ polymerization modified sulphoaluminate grouting material(PAM-SCGM)was prepared by one-step mixing method,and the properties and curing mechanism of the modified grouting material were studied.Finally,the modified grouting material was simulated and applied,and some achievements were obtained.(1)Performance of sulfoaluminate grouting material(SCGM).After adding lime,the initial setting time of the mixed slurry was kept between 3.0 min and 4.5 min,and the final setting time was between 7.0 min and 10.5 min,when the lime-anhydrite ratio was 1:7,the flexural strength at 1 d,3 d and 28 d increased by 73.3%,52.6% and 31.8%,respectively,with the flexural strength at 3d age reaching the maximum value.The compressive strength at the corresponding age reached more than twice the compressive strength of the specimen without lime.The optimal lime-anhydrite ratio is 1:7～3:5.(2)Performance of in-situ polymerization modified sulfoaluminate grouting material(PAM-SCGM).The components of in situ polymerization modified grouting material include acrylamide,initiator,cross-linking agent and inorganic grouting material.The slurry has good fluidity to meet the engineering requirements;the maximum heat storage temperature is below 90℃,and the flexural strength of the crystalline body can reach 11.7 MPa and compressive strength can reach 32.0 MPa after curing for 2 h.The damaged specimens are plastic fracture with 74% deformation,and the maximum heat storage temperature is less than 90.6℃,and the water absorption and expansion rate can reach 80.3%.The stone body has good stability and durability.The mechanism of hardening is the heat generated during the hydration of inorganic grouting materials,which triggers the polymerization of acrylamide radicals,thus forming an interpenetrating network structure of inorganic rigid skeleton dominated by ettringite and flexible carbon chains of polyacrylamide.(3)The field industrial test shows that the grouting material modified by in-situ polymerization is a kind of grouting material with superior performance,and has remarkable reinforcement effect on broken coal.