Study On Porous Concrete Permeable Base

Whether to cement concrete pavement or bitumnous pavement, water is the main reason that causes the pavement structure to darmge. Setting pavement subsurface drainage system is the fundamental measure to exclude the water corning into the pavement. Permeable base is the most important component of the subsurface drainage system, and its materials composition, performance and structure design will directly relate to the drainage effect and long-term performance of the pavement. According to this, the paper puts forward a kind of new permeable base material, which is called porous concrete.The paper starts from the water damage of pavement and its treatment, narrates the recent study of pavement subsurface drainage system and permeable base, and brings forward the problems to be solved. And then the drainage performance of porous concrete is studied, porosity and coefficient of penneability are thought to be good targets of its drainage performance, and the dependence relation of coefficient of permeability and porosity is drawn by tests with the permeameter developed by the author. The mix design targets and criteria of porous concrete are advanced, a series of relation formula of strength and porosity under vibration method and internal vibration method are regressed with orthogonality test design and uniform test design, and then the empirical formula method of porous concrete mix design are offered. The mechanical properties of strength and stress-strain c f porous concrete are researched, and the strength development with time, relationships between different strength and modulus and strength etc. are drawn. The physical properties of temperature contraction, dry shrinkage, anti-erosion and frost resistance are also proved to be fine by tests and mechanism analysis. Indoor flexural fatigue tests are carried out, the results are analyzed and two types of double logarithm fatigue equation under different stress level andequivalent stress level are got. Using the fatigue equation, the fatigue performance of porous concrete and common semi-rigid base materials and cement concrete are compared, the fatigue stress coefficient which is used in the load stress calculation for porous concrete as undersurface of cement concrete pavement and the tensile strength structure coefficient which is used in the flexural stress check for porous concrete as base of asphalt pavement are obtained.The requirements of structure combination for cement concrete with porous concrete base are put forward. Started with the analysis of temperature field, the temperature-warping stress and temperature contraction stress of porous concrete are studied, and the location of joint are discussed. At last, integrated with stress anddrainage analysis, the structure design method of cement concrete pavement withporous concrete base is suggested.