Experimental Study On Cement-Acrylate Composite Grouting Material

With the development of modernization in China,the transportation track and infrastructure have been developed in a large depth direction,and subway tunnels have been constructed more and more frequently in sand-pebble water-rich strata.This formation is rich in water volume and poor in stability,which has great excavation difficulty and high costs and risks.As a common reinforcement and water-stopping measure,grouting technology has been widely used in construction,water conservancy,transportation and other fields.In the past,most of the grouting materials used in sand-pebble water-rich formations were cement-water glass composite slurry,but after the improvement of previous people,it still has the defect that the properties of the slurry change sensitively with the concentration of water glass.The coagulation strength cannot reach a high level,and the anti-dry and wet cycle performance and expansion performance are not excellent.Therefore,it is urgently needed to innovate the traditional slurry.This article starts with the introduction of acrylate slurry,which is compounded with ordinary silicon cement mixed with lithium-based bentonite.Through the laboratory test to optimize the proportion and simulation test detection,a new type of grouting material was obtained.The specific research content is as follows.?1?Appropriate raw materials are used to prepare acrylate slurry,and a single-factor test scheme was designed to study the changes of slurry properties and gel mechanical properties with the content of each component.The most significant additive affecting acrylate grouting materials is the initiator ammonium persulfate,and the optimal blending amounts of the main agent,crosslinker and accelerator are15%,3%,and 1%.?2?Acrylic grouting material has good fluidity,its gel time ranges from tens of seconds to several minutes,its permeability coefficient is generally in the order of10^-7cm/s,and it has swellability in water-rich environments.It is suitable for long-term storage and is non-toxic or low-toxic after safety analysis.?3?The mechanism of composite action of cement slurry and acrylate slurry was analyzed.Lithium-based bentonite content and ammonium persulfate content,water-cement ratio,and poly-ash ratio were set as influencing factors of the composite slurry.Through experimental research on water separation rate,viscosity,gel time,compressive strength,permeability coefficient,and corrosion resistance,the optimal ratio of composite grouting material is water:acrylic acid slurry:cement=3:3:5.the content of lithium-based bentonite is 20%,and cement is mixed with 20%lithium bentonite,and the acrylate slurry contains 0.6%ammonium persulfate.?4?According to the requirements of grouting,a simple simulation test device was designed,and the grouting formula was applied to simulate sand and gravel formations,the characteristics of slurry diffusion,pore water pressure and slurry pressure were obtained,and the impermeability of the stone body was evaluated.