Mechanical Properties And Application In Subgrade Of Cement-Based Foamed Concrete With Silt

Due to the advantages of light weight,adjustable strength,high fluidity and self-standing after solidification,the foamed cement is increasingly used for the filling of soft foundation embankments,abutment backfilling,road expansion and etc.However,the dosage of cement in traditional foamed cement was large,resulting in a high price,which cannot be widely used under the existing conditions in China.The existing research on foamed cement is mostly limited to physical,mechanical and durability properties.The bearing properties of foamed cement as a roadbed filler are not clear,and the applicable layers of different mix ratios in subgrade cannot be clearly determined.To some extent,the application of foamed cement in engineering was limited.Based on this,this paper combines the extensive distribution of silty soil engineering characteristics in the alluvial plain of the Yellow River to develop a new type of foamed cement-Foamed Cement with Silt,which takes silty sand as raw material soil,and replaces part of the cement,can reduce the cost to a certain extent.At the same time,in order to study the application layer of foamed cement with silt in the subgrade,the indoor model test of strip foundation was designed and combined with numerical simulation to obtain the allowable tensile stress of different mix ratios and the applicable layer of foamed cement with silt in the subgrade.This paper obtained several results which were showed following:(1)By adjusting the wet density of foamed cement with silt and the amount of silty soil,the water absorption,unconfined compressive strength,saturated compressive strength,flexural strength,(static)elastic modulus and CBR were tested.The wet density and silty soil content are positively correlated and negatively correlated with the above indicators.Based on the test data,the wet density and silty soil content were established formula with unconfined compressive stress and flexural strength respectively.(2)By carrying out the indoor model test and considering the variation of the strip foundation height,the force,deformation and crack propagation law of the strip foundation under different load conditions are studied.The test showed that larger the ratio of length/height(L/H),the greater the bottom tensile stress under the same load and the earlier the crack is generated.The research results provide basic data for theoretical analysis.(3)At the same time,through the numerical simulation analysis,the sensitivity and application layer of the influencing factors of foamed cement roadbed are studied.It is proposed that the larger the height,width and(static)elastic modulus,the larger the damage load is.And it is recommended to use the foamed cement with silt with a wet density of not less than 700kg/m3 in the roadbed area,and the application standard in the embankment area is proposed.