Research On Durability Design Of Road Cement Concrete

Because of the high strength of cement concrete pavement and the extensive source of cement, the cement concrete pavement has been widely used, however, by the action of the contemporary heavy-load traffic and the natural environment factors, the durability diseases of cement concrete road is serious increasingly, durability of concrete has already become the focus in the concrete field. Durability design is the most important key part of road concrete mix design system, but the existing design methods is difficult to represent the characterization of the real durability working condition of our country's road concrete, and causing startling cost of maintenance due to durability diseases of cement concrete road. Aiming at the present situation, this paper relies on the Item of Communications Construction Science and Technology in West China "The Study on Design of Road Concrete Mix Proportion", based on the advanced concepts both home and abroad, the design method of road concrete mix proportion is researched thoroughly and systematically.The author in this paper comprehensively investigated and analyzed the domestic and international research conditions of road concrete at first, and thought that the durability diseases of cement concrete road and the pavement damage mechanism is a complicated problem which is the result of many factors comprehensive influence. It relate to not only the raw materials, the design of road concrete mix proportion and construction, but also the traffic load, the partition of climate environment, temperature stress and the corrosive medium.On the basis of the analysis relationship between road concrete's state of the internal structure and the material composition, the author designed a scientific and rational research scheme, and optimized the evaluation and testing methods which can reflect the actual durability damage state of road concrete. The relation between the material mix parameters and the impermeability of chloride, the frost and salt resistance, the abrasive resistance and the anti-slip performance of road concrete is also studied systematically by many tests and theoretical analysis, and the various design models of durability is established; Through analyzing the common and difference among durability design requirements which is caused by the different materials, consulting the large number of domestic and international advanced experience, the traffic load classification and durability partition of climate environment is put forward; The reasonable range of road concrete mix parameters under different durability partition such as water-cement ratio, the amount of water consumption and cement consumption, air content, mortar volume component and NMPS, etc. is proposed; The permanent damage and performance degradation model of road concrete is analyzed, and the mechanism of durability improvement which is caused by material design optimization is explored; In order to find a more simple, shortcut testing method, the evaluation indicators of the pavement performance about durability which is easily detected such as frost resistance, wearability was found, and the relative standards is suggested.This paper recommends for the first time the reasonable range of road concrete mix parameters under different climatic regionalization and load classification, based on the design of impermeability of chloride, the frost and salt resistance, and the abrasive resistance; Using as basis for the volume design concept, the durability design method, verification and adjustment of the processes and procedures is first presented, and the maneuverability and practicality of concrete durability design is verified by combining the actual project.