Multiple Index Composition Design Method Of Road Cement Concrete Based On System Theory

Composition design of Road Cement Concrete is a system project It not only involves advanced design concepts and methods, but also concerns our country's traffic loads of different grade roads and areas, environment condintion,performance of raw materials and construction management level. Relying on Item of Communications Construction Science and Technology in West China"The Study of Road Concrete Composition Method", in-depth and systematic research for the road concrete's composition design method is conducted with advanced concepts at home and abroad according to deficiency of existing design method.By introducing new concept of system theory, based on the unique structure of road concrete, raw material characteristics and the actual working conditions, the performance design ideology by stages is proposed and the level-division volume design model is constructed. Relying on the design partition of multiple index and multi-parameter control concept, this paper proposed the basic composition and design procedure of Road Concretes Design Partition(RCDP).In view of characteristics of road concrete's interior structure, road concrete level-division volume design model is constructed with mortar volume component(Vm) as its core. Firstly, the level design of mortar is carried out in this paper and the performance design indexes and the volume design indexes are determined.To ensure the smallest porosity for coarse aggregate principal skeleton, the design method of skeleton coarse aggregate is studied and the reasonable value of the aggregate gradation ,NMPS and the key control particle size are recommended. With the impact of mortar on coarse aggregate skeleton, layer design of road concrete is studied. According to the significant relationship between Vm and the road performance of concrete,the method of determining Vm is proposed.Considering the material properties, concrete design partition concept is shown through concrete road analysis of environment and role characteristics. Design partition systems include traffic load classification, durability partition of climate environment and construction environment grade. According to various environmental factors, the signifitance and effectivity of the working environment are distinguished, using traffic volume, mean temperature of coldest months, rainfall, intensity of the coefficience of variation and evaporation rates for traffic, weather, construction design of three types of zoning district indicators. In view of the application of our country, the specific design partition is defined and the relevant district is described and on road performance requirements, a basic framework for the partition system design is established.Multiple index and multi-parameter system of design partition in this paper constitutes a concrete path established by the design of the foundation. Multiple indicator system is used in the paper for control the composition of concrete road design, combining theoretical analysis and experimental research, the accuracy of evaluation of the different indicators of road concrete's road performance is analyzed, then slump and VB consistency are recommended as construction flow degeneration design specifications, flexual tensile strength for mechanical properties of design specifications, impermeability, frost resistance and wear resistance of chloride ion for durability of design specifications, lastly reasonable value of a variety of road performance indicators is recommended.The establishment of multi-parameter system achieve effective control of the composition design process of road concrete. Based on the analysis relationship between road concrete's state of the internal structure and the material composition, a research object and testing methods are optimized, scientific and rational design of the laboratory test programme are designed, the relationship of road concrete between the key materials parameters and construction rheology,mechanical properties, durability and crack resistance is studied. The results indicate that the water-cement ratio is the most important component design parameter,and the relationship between water-cement ratio, flexural bending strength and durability is the mixture ratio design foundation, even to maintain the same water-cement ratio, changing in cement consumption or the amount of water consumption of cement has a significant difference in road performance of road concrete,therefore, the design must control these three parameters simultaneously; in addition, the appropriate net slurry and air content in the concrete road are very imporant to enhance the durability and the crack resistance. Through the analysis of different materials on the road performance of the design requirements of the common and differences and give full consideration to the application of concrete roads, referring the research results both home and abroad, the reasonable value range of the road key component of concrete parameters of different design partition. is recommended corresponding to the road concrete in the paper.Lastly, on the basis of comprehensive analyse for relative research, the road concrete mixture design method is established which is based on the pavement performance, the design software is developed, and the maneuverability and practicality of mix design method by combining the test project is verified.