Study On The Concrete Of Shield Segment Steel Slag Used In Metro

Steel slag contains some C₂S,C₃S and other minerals,but also contains a certain amount of free calcium oxide（f-Ca O）and free magnesium oxide（f-Mg O）,with potential gelation properties.However,due to the denser mineral crystals of the steel slag,the lattice is more stable,and the hydration activity is relatively low,thus hindering its large-scale application in the building materials field.In order to increase the utilization of steel slag resources and solve the problem of ecological environmental pollution,therefore,this paper studied the effect of steel slag on the volume stability of concrete.Influence of different pretreatment methods on mechanical properties of slag concrete and effects of mineral compound admixture and steam curing on mechanical properties of segment concrete,the main results are as follows:（1）The stability test results show that,the content of steel slag powder in concrete should not exceed 30%;the maximum content of steel slag sand should not exceed 50%;the maximum content of steel slag stone should not exceed 30%.（2）Although the steam treatment can reduce the f-Ca O content,it also reduces the activity of the steel slag.The addition of the acrylic emulsion before concrete molding has an adverse effect on the strength of the concrete.After the concrete is formed,taking the acrylic emulsion coating on the concrete can further improve the waterproof capacity of the concrete.（3）The activators significantly improve the activity of steel slag,thus improve the strength of the steel slag concrete;Only mixed 1%Na OH excitation effect of steel slag concrete is the most obvious,the 28d strength even more than the ordinary concrete strength.The steel slag concrete under different activators role in curing 28d,difference obvious compressive strength performance,and the three time configuration of exciting agent mixed,such as 4%Na₂SO₄,1%Na OH,1%Na₂Si O₃ effect of steel slag concrete is best,compared with the steel slag concrete is not mixed with exciting agent the 28 d strength growth effect value reached 23.4%.（4）Water-binder ratio had a smaller influence on the early strength under steam curing system,the compressive strength of the standard curing conditions is big.When the total amount of slag powder,fly ash and slag powder is 20%,the strength of the mould is higher than that of other admixture,considering the resource utilization of economy and industrial waste residue,the content of 25%of the optional strength gap is not very high;Quiet time 2 h after the specimen molding,and then at 15℃/h the heating rate of up to 55℃,the temperature at 15℃after 4 h rate of cooling down to room temperature pipe technology can get high form removal strength.（5）The slag concrete immersed in the sulphate solution for eight months has good erosion resistance,and the corrosion resistance obtained at different ages is greater than 0.85 Segment concrete anti-chloride ion permeability can reach RCM-IV level.