Plant Mix Recycled Bituminous Grading Design Research

The period of new road construction and old road rebuilding has been coming in China. Most of the roads which need to be reconstructed are bitumen roads. So if those roads were to be reconstructed, much bitumen and stone would be needed. The technology of recycling the waste bitumen as well as other materials can make the best use of the waste materials and avoid using large quantity of sand. In addition, if this technology is applied, large areas of land resources can be saved from being used to exploit sand or to store the waste materials. Though this technology of recycling bitumen has been researched systematically and abundant researches and experiences are worth studying and learning from, we still face many technical problems. This thesis intends to find the best grading design for plant mix applicable in Xi'an and the practical way to be applied in the road construction, which is based on a consideration of the climate conditions in Xi'an and systematic test, the road properties and characteristics of the recycling material.This thesis studies the roads built from 1990 to 2002 and compares the different qualities of the used bitumen and the recycled materials. Through the test of the recycled old bituminous surface course, the answer of how much of the additional materials should be added will be given. The ways to make the plant mix recycled bituminous and to apply these new materials to the road construction will be discussed in this paper. These are the basic materials for the grading design.Both the new bitumen and new sand are added. Marshall Test is used to make the grading design. Four factors are discussed in the grading progress: intensity, friction, anti-infiltration and stability. The standard grading design is based on these four factors and is applied to the factory.The application of the plant mix recycled bituminous surface course and the quality of the materials are both checked to make sure that the grading design is reasonable, especially in the area of Xi'an city.