Study On The Performance Of Neutral Activated Steel Slag Powder And Its Application In Cement Stabilized Crushed Stone

Steel slag is the most residual solid waste in the process of industrialization in China.Improving the utilization rate of steel slag has become the focus of solid waste disposal.The existing research shows that the steel slag has gelling activity.Compared with Portland cement,its hydration activity is not high,and it also contains harmful components.At present,alkaline activation and acid activation are mainly used at home and abroad,which can not give full play to the potential activity of steel slag powder and can not tap the potential economic value of steel slag.This article relies on the highway reconstruction project of the Changzhi transit section of State Road 207.Taking steel slag powder of Taiyuan Iron&Steel Co.,Ltd.as the research object,selects the neutral compound chemical activator to activate the activity of steel slag powder.The micro-analysis and research on the hydration products of the activated steel slag micro powder and cement composite powder gelling system were carried out,and the application of the activated steel slag micro powder and cement composite cementitious materials in the pavement base was promoted through laboratory verification tests.Firstly,on the gelling properties of slag powder TISCO analysis results show that steel slag contains calcium oxide,silica,magnesia,iron oxide and other ingredients.The minerals that provide gelling activity,such as tricalcium silicate and dicalcium silicate in the Steel slag powder,are much lower than cement.The hydration products of steel slag powder are similar to those of cement,but the quantity and type of hydration products are smaller than that of cement.There are a lot of periclase in the hydration products of steel slag powder,which leads to poor stability.Secondly,through physical and mechanical performance experiments and micro-analysis of hydration products,the neutral composite chemical activator of the steel slag powder is optimized.The experiment showed that after adding activator,the compressive strength of steel slag powder was increased to 9.2MPa in 3 days,16.9MPa in 7 days,and 27.5MPa in 28 days.Hydration products such as calcium hydroxide,ettringite crystals,calcium silicate are produced,and the amount of periclase is reduced.The performance of neutral activated steel slag powder and cement composite cementitious material was studied.When the cement content was 30%,the compressive strength was 14.4MPa in 3 days,24.5MPa in 7 days and 38.1 MPa in 24 days.The SEM,XRD and TG-DTG analysis of the hardened paste show that the hydration products are constantly dense and there are more types of hydration products than cement,but the total quantity is less than cement.Finally,the neutral activated steel slag powder and cement composite cementitious material is applied to the pavement base.Design the mix proportion of steel slag powder and cement stabilized crushed stone base.Based on the 7-day unconfined compressive strength test results,its performance is evaluated.The test results show that the neutral activated steel slag powder can replace most of the cement and be used in the pavement base.Although the unconfined compressive strength of the neutral activated steel slag powder and cement stabilized macadam for 7 days is not as good as that of the cement stabilized macadam,it can meet the use requirements of the subbase.It can be considered to meet the use requirements of the base by increasing the dosage.