Stability Experimental Research On Highway Base Loess Mixed With Steel Slag Powder

Traditional treatment on highway base loess is mixing lime and fly ash into soil to improve properties and increase strength for meet requirements, but the practice found it has low pre-strength, small shrinkage coefficient and large water sensitivity. The steel slag combined with new treatment process "hot braise method" has better pulverizing effect, lower free calcium oxide content, lower expansion, more stable properties, apply it to the highway base soil not only solve the problems of disposal of steel slag, but also can improve the strength of base material, control the deformation of base material and enhance the stability of the base.In this paper, taking steel slag powder, lime, fly ash and loess formulated to mix in different steel slag content, names "steel slag lime-ash soil", then measuring the volume change caused by one-way immersion expansion and normal temperature water loss through laboratory test, also the compressive strength under a variety of analog local climate conditions such as water-saturated, dry-wet cycles and freeze-thaw cycles. Using comparative tests method to analyze and research the stability of steel slag lime-ash soil by internal and external factors.The results show that: The range of the optimum water content of steel slag lime-ash soil is wide, which conducive to site construction; The swelling deformation of steel slag lime-ash soil is smaller than 3: 7 fly ash soil, and they both meet deformation requirements of highway base in specifications; With the increasing of steel slag content, the maximum shrinkage strain and average shrinkage coefficient of steel slag lime-ash soil tend to decrease but all better than lime-ash soil and 3: 7 fly ash soil, indicating that steel slag can effectively improve the shrinkage performance of the mix; Under a variety of natural environment simulated conditions, the unconfined compressive strength of steel slag lime-ash soil are all higher than the other soils, which show that steel slag lime-ash soil has better water stability. Effects of steel slag content:(1)the swell increment increases with the increasing steel slag content(2) the shrinkage decreases with the increasing steel slag content(3) the unconfined compressive strength increases with the increasing steel slag content in water-saturated test and freeze-thaw cycles test, for the degree of impairment of compressive strength, medium content steel slag lime-ash soil is lower than high content steel slag lime-ash soil, and in these conditions the best steel slag content is between 30% to 50%; In dry-wet cycle test, the degree of impairment of compressive strength increases with the increasing steel slag content, so in this condition, the best steel slag content is between 10% to 30%; The optimum moisture content range of steel slag lime-ash soil is wider, which is conducive to the site construct and has good practical value.Steel slag lime-ash soil can keep excellent mechanical properties and pavement performance, control volume change to a certain extent and keep high compressive strength under water-saturated and different climate to ensure the stability as well, it is a good highway base materials with well stability.