Research On Performance And Design Method Of Unbound Aggregate Base

Reflection cracking and water damage are important factors, which influence the performance of semi-rigid pavement. For solving these disadvantages, in this paper, it suggests that high-quality unbound aggregate with strict gradation and construction be taken as upper base course between semi-rigid course and asphalt surface. Structural design method of unbound aggregate upper base is analyzed through field test, laboratory test and theory study. On the base of former study conclusion, it suggests physics index of unbound aggregate. And it analyzes the mechanical properties of unbound aggregate in different shaping modes. The factors infect mechanism of unbound aggregate are found. As a result, it suggests reasonable gradation, which can structure high-quality unbound aggregate upper base.Resilient modulus reflects the change of stress. Repeated dynamic load triaxial test is the best method which can be used to study characteristics of resilient modulus of unbound aggregate. Triaxial tests were carried with different gradation unbound aggregate in different moisture content. Model of resilient module and influencing factor are found.The rational proposal and requirement for construction technology of granular base course is recommended. Through comparing the data from test road, characterize of unbound aggregate upper base were found.After unbound aggregate being settled in the semi-rigid pavement, there are great changes in structural stress distribution and form of structural default. Main form of structural default is found in semi-rigid pavement with unbound aggregate upper base through contrasting. And it suggests control index of structural design.Refer to the design method of flexible pavement with unbound aggregate base in foreign countries. Adopting orthogonal method to analyze main factors effect on module of unbound aggregate. Finally, it suggests design index of semi-rigid pavement with unbound aggregate upper base.