Research On Preparation And Percormance Of Steel Slag Asphalt Pavement

Steel slag is by-product of steel making process. China produces the most steel among the world, meanwhile, more than 100 million tons of steel slag is produced every year in China. However, less than 25% of steel slag has been put into utilization. On the contrary, the last three decades have witnessed the rapid development of road engineering, and the pace is not stopping. Aggregate of good quality is badly needed during these years. In our country, semi-rigid base and asphalt pavement is frequently used when constructing highways, which consume large amounts of aggregate. Steel slag, which is properly produced, bears a lot similarities with crushed natural rock. Steel slag is potentially to be aggregate of great quality, when taking its dense, solid, rough, and hard-wearing properties into account. Thus, using steel slag in asphalt pavement as coarse aggregate, will surely bring enhancement to pavement quality, on the other hand, bring benefit to society, economy and environment.This dissertation focuses on the steel slag from Nanjing Iron&Steel United Co.LTD. The main thesis is to use steel slag as coarse aggregate in hot mix asphalt pavement. Aggregate properties, mixture designing and preparation method, mixture properties and basic road performance, gradation optimum design, and issue of practical engineering is studied sequentially.Firstly, Physical and mechanical properties is evaluated by testing its density, water absorption, crushing value, abrasion value. Chemical property and micromorphology is studied by XRD and SEM. Secondly, to ensure the right mix designing method, density converting rule is put forward and tested. Effective density is tested by asphalt immersion test. Based on the former study, two basic types of asphalt mixture -AC and SMA- is designed and prepared and optimal asphalt content is determined. Thirdly, by comparing with normal hot mix asphalt pavement, high temperature stability, low temperature cracking resistance, moisture susceptibility, and swelling property of steel slag hot mix asphalt pavemen is evaluated by different method, which are penetration resistance test, rutting test, dynamic modulus test, trabecular bending test, freezing-melting splitting test, swelling test, British pendulum number test, dynamic friction test. Fourthly, angularity of steel slag is evaluated by testing its initial angle and image processing method. Furthermore, gradation optimum design is conducted concerning the parameter VCAmix.Finally, drying process is simulated in lab to acquire the curve of drying rate. And thermal field is simulated using Abaqus to study the compacting process of pavement constructing.