Study On The Performance Of Open Graded Cement Stabilized Aggregate For Pavement Base

Water damage of asphalt pavement is one of the common diseases of highway early. Exhausting the water of pavement structure layer quickly is an effective way to reduce the water damage. In addition to the surface and subsurface drainage, we can also strengthen internal drainage of the road by setting drainage base. Open graded cement stabilized aggregate(OPCSA), as drainage base material, has attracted much attention in recent years for its good drainage performance, and in the theory and practice of research achievements of the scholars have also been widely used. The purpose of this paper is to research OPCSA’s performance by theoretical and experimental study, and to expect that the research results can contribute to practical projects.Firstly, the paper focuses on drainage base material design, proposes reasonable graded level and best cement content; choose coarse and fine open-graded material respectively as research subjects and regular graded material as contrast; considering two kinds of construction method, the paper conducts simulations based on indoor static compaction molding and vibration compaction molding. Main research topics include: strength properties, stiffness properties, shrinkage properties, frost properties,anti-erosion properties, and water permeability. Results show: compared with static compaction molding, vibration molding specimen has better strength and stiffness performances; OPCSA outweigh conventional graded material more than 1.6 times at shrinkage coefficients, also increasing fine aggregate content can effectively reduce shrinkage coefficient, but the temperature shrinkage coefficient will enlarge, vibration molding specimen has a better shrinkage properties compare to the static compaction molding specimen; frost resistance of OPCSA is about 10% higher than that of conventional graded material, and anti-erosion of the former is also stronger; OPCSA produced by static compaction molding has better anti-frost performances than that by vibration compaction molding, but it is the opposite case for anti-erosion performance;water permeability of OPCSA outweigh that of conventional grading more than 6times, and there is a exponential relationship between effective porosity and permeability.Emerging discipline fractal theory in mathematics research has also achieved success in civil engineering study. By applying fractal theory to OPCSA materialresearch, the paper analyzes calculation methods of graded fractal dimension, and the relationship with effective porosity, and calculates volume fractal dimension, from both theoretical and experimental perspectives. Results show that: effective porosity and graded partitioned fractal dimension has notable quadratic relationships; the smaller the grading fractal dimension is, the better the drainage performance is.Finally, combing practical drainage performance testing highway construction from Jiehualong to Chaling(Longcha) in Hunan province, the study analyzes primary control indicators in drainage base, including design strength, drainage base thickness,the maximum percolation time, drainage base system, etc. Results show that: the test sections fully meet designed requirement; drainage base system and general edge drainage system both have advantages and disadvantages.