| Asphalt concrete and Portland cement concrete are commonly used as pavement materials nowadays. But, the use of these types of concrete in tunnels is restricted. Rubberized lightweight aggregate concrete (RLC) is a kind of new environment-friendly pavement material that has low elastic modulus, high toughness, good workability and durability. Therefore, it is very suitable for the construction of pavement in tunnels of express highways. In this thesis, a serial of experiments and systemic researches is carried out which is focused on the constituents, structure and performance of RLC. Based on the systematic study on the mechanical performance, durability and microstructure of RLC, the relation among the constituents, structure and performance of RLC and the joint effects are investigated. Considerting the practical applications, this new material is applied in the design of tunnel pavement and a composite tunnel pavement structure (PCC—RLC) is put forward. Key techniques for the preparation of RLC and its applications in composite tunnel pavement are addressed, which can be used to guide the development and application of RLC.The main research work and achievements presented in this thesis are outlined as following:From the aspects of development strategy, economic and technical demand, the design of RLC composite tunnel pavement is divided into three levels. Based on this three-level design, a design concept for RLC composite tunnel pavement is put forward, which may guide the design, preparation and application of this new material. Based on the analysis of the relation between the constituents and structure of RLC, a distributed three-phase composite model is built; three main modified theories of interfacial strengthening, polymer modification and strain energy are applied, which are the theoretical foundations for the design and preparation of RLC.Based on the design concept and modified theories, the recipe of this type of concrete such as rubber particle size, lightweight aggregate type, additives, polymer and sand ratio is studied and effective rules about its workability, mechanical performance and durability are concluded. Based on results of the micro-hardness test, polarizing microscope image analysis and SEM images, the hardening mechanicsms of RLC are analyzed and the relation between the constituent and performance is revealed by using the microcosmic methods. Key propertyes such as low elastic modulus, high toughness and good durability are obtained. RLC with compressive strength of 15～20 MPa, tensile strength of 1～3 MPa, elastic modulus of 10000～15000 MPa and ultimate tensile deformation of 0.01～0.03 is developed. It has low shrinkage, high toughness and good durability as well.Considering the special working condition of tunnel pavement, a RLC composite tunnel pavement (PCC—RLC) structure is developed, which comprises a Portland cement concrete strengthening layer as the base (PCC) and a RLC layer as the up layer (RLC). By using finite element analysis, the distribution of stress and strain in this PCC—RLC structure under the vehicle and temperature loads are studied, which are the mechanical and theoretical foundations for the design of PCC—RLC.Key techniques such as mixing, transportation, pouring, vibration and curing, etc. for the engineering application of RLC are studied systematically. Critical techniques for the construction of PCC—RLC composite pavement are put forward in this thesis as well. Quality control methods are proposed, which may be used to guide the production and application of RLC.
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