| Silica fume is a kind of fine particulate matter,which is collected and processed by a special trap device in the procedure of smelting industrial silicon and ferrosilicon at high temperature in industrial electric furnaces.Partially replacing the mineral powder,silica fume advances in lowering cost,reducing energy consumption and facilitating environmental benefits.Based on the experimental study,this paper analyzes the mechanical properties of silica fume mortar and the pavement performance of silica fume asphalt mixture.The main contents of this paper are as follows:（1）Micro-performance test and analysis of mineral powder and four types of silica fume.（2）Employing direct shear test to evaluate the shear performance of silica fume asphalt cement,along with deep cause analysis.（3）Devising the mix proportion of silica fume asphalt mixture with Marshall method applied.（4）Examining the pavement capability of silica fume asphalt mixture,which comprises water stability,low temperature crack resistance and high temperature stability.The primary conclusions come out:（1）SiO2 is the major component of silica fume whose fineness modulus is obviously smaller than that of mineral powder;additionally,both particle fineness and the pore characteristics of particle surface manifestly do matter in the specific surface area of silica fume or mineral powder;moreover,the numerical value of specific surface area of silica fume and mineral powder is consistent with the value of total pore volume.（2）When the vertical pressure is 200 kPa,the shear strength of silica fume cement is 1.4-2.4 times than that of mineral powder cement;furthermore,the larger the specific surface area of silica fume,the higher the shear strength of asphalt cement;besides,the significant growth of the c value of the cement contributes tremendously to the increase of the shear strength;however,the c value of silica fume cement relate tightly to the specific surface area of silica fume.（3）For silica fume asphalt mixture,the difference of water stability is affected by the content of SiO2in silica fume;in addition,the water stability of alkaline silica fume asphalt mixture is superior to that of mineral powder while the acidic is worse than mineral powder;likewise,the low-temperature performance of 4#silica fume is better than that of mineral powder whilst the other three kinds of silica fume are slightly poorer than mineral powder;The dynamic stability of silica fume asphalt mixture is higher than that of mineral powder;meanwhile,the greater the specific surface area of silica fume,the higher the dynamic stability. |
