Research On Performance Of CRTSⅢ Slab Track Filling Layer With High Performance Grouting Filling Material

CRTSⅢ type slab ballastless track has been widely popularized in China.The preparation of high-speed rail track filling layer self-compacting concrete needs to incorporate superplasticizer and various mineral admixtures,so it’s Working performance is affected by many factors.In order to meet the requirements of the filling layer of self-compacting concrete,the absolute volume method is used to calculate the benchmark mix ratio,and the amount of mineral admixture,superplasticizer,and water/binder is optimized by a large number of tests to determine optimal mix ratio,Also,the densification of the microstructure of hardened concrete was verified by SEM examinations.In order to further evaluated the Working performance of self-compacting concrete by indoor simulation pouring and exposing-plate test.The main research contents are as follows:(1)According to the requirements of the self-compacting concrete material of the highspeed rail filling layer,the raw materials and additives that meet the preparation of the selfcompacting concrete are screened out;the benchmark mix ratio is calculated by the absolute volume method,and the EXCEL is used to make the automatic calculation table for mix ratio.(2)Proper amount of slag powder can improve the workability of self-compacting concrete.When the content of slag powder is 15%,the workability of self-compacting concrete is optimized;Silica fume can greatly improve the cohesive performance of self-compacting concrete and reduce the bleeding and slurry flow significantly.When the content of silica fume is 5%,the performance of all itemes is relatively superior;The appropriate amount of fly ash improves the rheological properties of the concrete.But fly ash is easy to floate up and accumulate on the upper surface of the self-compacting concrete if it’s more than the certain amount,which will lead to the viscosity decreases.The parameters are relatively good when the fly ash content is 15%.With the increase of the superplasticizer content,the degree of expansion and fluidity of the filling material are significantly improved,but when the superplasticizer content is more than 2.3%,the self-compacting concrete appears the phenomenon of segregating and creaking.So the content of Silica fume is 5%,the content of slag powder is 15%,the content of fly ash is 15%,and the content of superplasticizer is 2.3%All the workability of the self compacting concrete match the standard.(3)Carrying out indoor simulation pouring test and exposing-plate test on the selfcompacting concrete under the optimal mix ratio,and perform different workability tests on the self-compacting concrete before pouring to meet the requirements of CRTSⅢ type high-speed rail track filling layer.the surface of self compacting concrete shall be in good contact with the bottom surface of the slab and the top surface of the board;and the cut section shall be compactness,fullness and flatness,and no exposed stone,honeycomb,concave seam and other phenomena.The optimal mix ratio meets the requirements of self-compacting concrete to pour into the filling layer of high-speed railway.