Semi-rigid Base Layer Research Articles

Influence on the Stress of Pavement with Crack in Base from Flexible Transition Layer under Dynamic Loading

After cracks appear in the semi-rigid base layer, the stress mode of pavement structure transits from infinite continuum to limited size board, and the cracks become stress concentration areas. Based on the practical tire contact pressure and contact area, this paper establishes the C3D8R model by ABAQUS, to calculate and analyse the influence on the base cracks extension from graded gravel transition layer under half-sinusoid load. Analysis shows that the graded gravel has excellent stress dissipation ability. Whether there are cracks in the base, the graded gravel transition layer between asphalt surface layer and semi-rigid base layer could greatly reduce the tensile stresses in the bottom of semi-rigid base and subbase layers, improve the road bearing level, delay and avoid the cracks extension to deep road and prolong the road service life.

Influence on the Stress of Pavement with Crack in Surface from Flexible Transition Layer under Dynamic Loading

After cracks appear in the surface layer, the stress mode of pavement structure transits from infinite continuum to limited size board, and the cracks become stress concentration areas. Based on the practical tire contact pressure and contact area, this paper establishes the C3D8R model by ABAQUS, to calculate and analyse the influence on the surface cracks extension from graded gravel transition layer under half-sinusoid load. Analysis shows that the graded gravel has excellent stress dissipation ability. Whether there are cracks in the surface layer, the graded gravel transition layer between asphalt surface layer and semi-rigid base layer could greatly reduce the tensile stresses in the bottom of semi-rigid base and subbase layers, improve the road bearing level, delay and avoid the cracks extension to deep road and prolong the road service life.

Mechanical Property of Pavement with Crack in Base and High Modulus Asphalt Layer

When the crack appears in semi-rigid base layer, the stress mode of pavement structure transits from infinite continuum to limited size board, and the crack tips become stress concentration areas. This paper establishes the three-dimensional eight nodes entity reduced integral unit model by the practical tire contact pressure and contact area, to calculate and analyse the influence on the mechanical indexes in pavement structure with or without crack in base layer from high modulus asphalt layer under half-sinusoid load. Analysis shows that enhancing the modulus of surface layer could effectively reduce the tensile stress in bottom of base layer and avoid the bending broken in base bottom, but there exists risk that the bottom subbase and asphalt layer cracking.

Design Guide for Semirigid Pavements in China Based on Critical State of Asphalt Mixture

Semirigid pavement is a type of pavement structure in which a semirigid base layer, usually made up of cement-treated base (CTB) or cement-stabilized base (CSB), is overlaid with a top flexible layer of asphalt mixture. Because a considerable amount of fly ash or other waste materials can be used in CTB or CSB and less petroleum-based virgin asphalt binder is required, semirigid pavements are a type of environmentally friendly and sustainable pavement structure. This paper presents a new approach for semirigid pavement design in China based on the concept of surface deflection at the critical state of the top asphalt mixture layer. On the basis of results from an extensive survey of over 50 highway sections in eight provinces in China, a quantitative relationship was developed between allowable surface deflection at critical state of pavements and accumulative standard axle load, from which an allowable surface deflection at the end of pavement service life was recommended for semirigid asphalt pavements. A method was then proposed to convert the allowable deflection at the end of pavement service life to the design deflection at the initial state of pavements. Finally, a new Chinese design guide for semirigid pavements was developed using the surface deflection at the initial state of pavement as a design criterion. The proposed pavement design guide was validated with two example projects.

The Composite Asphalt Pavement Structure Serrice Life Analysis which Setting the Graded Gravel between the Asphalt Surface Layer and the Semi-Rigid Base Layer

In this article, the three-dimensional finite element method was used to analyse the composite base asphalt pavement structure life, which setting the graded gravel layer between the asphalt surface layer and the semi-rigid base layer. The main effect considering on the service life were the face layer thickness, the graded gravel thickness ,the contact state and so on, and compared the compound base with typical semi-rigid base the service life of the asphalt pavement . The analysis shown that the road surface contact state was the biggest influence to the service life. When using reasonable pavement structure combination, composite base asphalt pavement generally wouldn't produce the service life of the decline .

The Composite Asphalt Pavement Structure Serrice Life Analysis which Setting the Graded Gravel between the Asphalt Surface Layer and the Semi-Rigid Base Layer

In this article, the three-dimensional finite element method was used to analyse the composite base asphalt pavement structure life, which setting the graded gravel layer between the asphalt surface layer and the semi-rigid base layer. The main effect considering on the service life were the face layer thickness, the graded gravel thickness ,the contact state and so on, and compared the compound base with typical semi-rigid base the service life of the asphalt pavement . The analysis shown that the road surface contact state was the biggest influence to the service life. When using reasonable pavement structure combination, composite base asphalt pavement generally wouldn't produce the service life of the decline .

Prediction of shrinkage cracking and corresponding cracking prevention measure of the semi-rigid base layer

Shrinkage cracking resulting from the shrinkage stress of the semi-rigid base layer is a dominant factor leading to failures of asphalt pavements with semi-rigid base layers. The calculation model of the shrinkage stress, which is caused by dry and thermal shrinkage, of the semi-rigid base layer was established. Based on the calculation model, the expression of the shrinkage stress of the semi-rigid base layer was deduced and the maximum value of the shrinkage stress was calculated, and the position of the maximum value was presented. Besides, the influencing factors of the maximum value of the shrinkage stress and the cracking rule of shrinkage cracks were analysed. The results indicate that the maximum value of the shrinkage stress can be reduced by decreasing the length of the semi-rigid base layer to control the free shrinkage of the base layer. In this paper, the cracking prevention measure of setting pre-cutting slots in the semi-rigid base layer is presented, and the setting details are introduced.