Research On Structural Characteristic And Component Design Methods For Semi-rigid Base Course Material

This paper includes several research of testing methods related to semi-rigid base course. First, a vibration compactor used in lab is invented, based on the machine, rational vibration parameters are given through experiment, then "Testing Methods of Determining Compaction Standard for Semi-rigid Base Course Material with vibration compactor" and " Methods of making sample with vibration compactor in lab" are presented. Secondly shrinkage coefficient measuring system for semi-rigid base course material is improved, and "Testing Method of temperature shrinkage coefficient for semi-rigid base course material" and "Testing Method of drying shrinkage coefficient for semi-rigid base course material" are given. In the research, MTS is used to study the rules of samples erosion quantity influenced by the factors such as frequency and force, and a special machine is invented to conduct erosion experiment for semi-rigid base course material, then "Testing Method of Anti-erosion Performance for Semi-rigid Base Course Material".According to distributing states of coarse mineral aggregates in the mixture, semi-rigid base course material is divided into three structural types: "suspend-dense" structure, "framework-dense" structure and "framework-pore" structure. As for "suspend-dense" structure, the demands of its raw material and aggregate gradation standard can refer to existing criterion, but no criterion can be used for "framework-dense" structure and "framework-pore" structure. For this reason some experiments are done in the lab to study the performances of compacted coarse mineral aggregate framework, such as porosity, anti-breaking performance, shear resistance performance and anti-deformation performance. Based on the experiment results, gradation range of coarse mineral aggregate and fine mineral aggregate for "framework-dense" structure and "framework-pore" structure mixture are recommended. At last, calculation methods of mixture composition are provided.The paper presents test results of performance for many kinds of semi-rigid base course materials including cement stabilized macadam and lime fly-ash macadam with different binder dosage. Test items include compression strength, split strength, anti-breaking strength, and modulus of compression, modulus of rupture, temperature shrinkage coefficient, humidity shrinkage coefficient and anti-erosion performance. Based on these data, performance of typical semi-rigid alteration rules and its rangeare got.In practice, the performance of base course affected by many factors such as temperature, humidity and vehicle loads. The paper presents a integrate semi-rigid mixture component design system which consider strength, shrinkage coefficient and erosion volume synchronously. In order to satisfy different situation, the methods consist two inferior methods, "choice method" and "test method", "choice method" used for material in common use, "test method" used for the usage of new material. Chapter 1 include meaning of the research work, home and abroad research situation and our research scheme. In chapter2, 3 and 4, test method of vibration compaction, shrinkage coefficient measurement and anti-erosion performance are researched respectively. In chapter 5, some aggregates gradation range and mixture component calculation methods are provided. Performances of different types of semi-rigid base course material are given in Chapter 6. Chapter 7 gives some mechanisms of test results. Chapter 8 describes the construction and inspection process of test road section in site. Semi-rigid base course material mixture component design method controlled by Integrate index is presented in Chapter 9. In chapter 10, main conclusions of the research work and the work which needs to do in the future are present.