Experimental Study On High Flexural Micro Expansion Duct Grouting

With the rapid development of bridges and roads in China,the construction of various railways and highways is taking off rapidly.The post tensioned prestressed duct grouting technology is indispensable in the construction of highways and railways.The key material of the post tensioned prestressed duct grouting technology is the grouting material,but there are problems such as high cost and large amount of cement.In order to solve the above problems,the common method is to mix minerals The compressive performance of the slurry can be guaranteed,but the bending resistance is poor,which makes the brittleness of the material increase and the bearing capacity of the structure decrease.Therefore,it is necessary to study the pore pressure potential of high flexural micro expansion mineral admixture for railway.On the basis of ordinary portland cement,sulphoal urinate cement was mixed into it to study the influence of different mix proportion on the fluidity,flexural strength and compressive strength of the duct grouting material,and to preliminarily determine the benchmark mix proportion of the duct grouting material.Based on the obtained standard mix proportion,fly ash,mineral powder and fine beads are tested respectively to study the influence of three materials on the performance of duct grouting material,and then the composite mixing comparison is carried out.At the same time,the railway grouting material that meets the specification requirements is obtained by using the admixture.It is found that mineral powder has the greatest influence on the initial fluidity of slurry,and fine beads have the greatest influence on the 30 min fluidity of slurry.In order to study the influencing factors of the bending strength of the railway pressure paste,the effects of nano silica fume,super absorbent resin(SAP),polyvinyl alcohol(PVA)and rubber powder on the bending strength were studied,and the best ratio of the four factors was determined.The influence of the four factors on the bending strength of the pressure paste was: nano silica fume > super absorbent resin > polyvinyl alcohol > 100 mesh Rubber powder.The best combination is 1% nano silica fume,0.1% super absorbent resin,0.3% polyvinyl alcohol and 3% 100 mesh rubber powder.