EXPERIMENTAL RESEARCH ON FEASIBILITY AND DURABILITY OF STABLE RED MUD IN ROAD USE

Red mud stabilized by cement-based mixture is widely used in highway engineering,which has become a new direction for consuming industrial solid red mud waste. At present,the research on durability of road-used stabilized red mud lags behind engineering practice. In order to study it,we conducted the stabilizer proportioning,W-D circulation,F-T circulation and micro test. The results show that the standard strength of red mud stabilized by cement,lime and phosphogypsum is at least 3.6 MPa which can meet the pavement base bearing standard. The mass loss of stabilized red mud tends to be stable after both five-staged W-D circulation and F-T circulation. As the proportion of phosphogypsum decreases from 8% to 2%,the strength after five-staged W-D circulation is reduced to 1.69~3.69 MPa,with the strength loss rate(BDR/%) of 35.1% ~85.4%,and the strength after five-staged F-T circulation is reduced to 2.63~3.70 MPa,with the strength loss rate(BDR/%)reaches 54.82% ~79.79%. In the stabilized red mud system,the amount of phosphogypsum should not exceed 2% of the amount of red mud. In addition,the micro-scale MIP test reveals that W-D circulation and F-T circulation both increase the pore volume of the sample. The increase of macropores(diameter>0.1 μm) significantly affects the strength. In conclusion,we reveal that it is feasible to use stabilized red mud as road surface cement-stabilized materials,and the optimal ratio considering load-bearing performance and durability is 100︰8︰2︰2 for red mud︰cement︰lime︰phosphogypsum ratio. Based on the characteristics of cyclic strength attenuation,construction period and early maintenance are important in engineering practice,and the usage of phosphogypsum in stabilized red mud system should be strictly controlled.