| Based on the construction of bituminous concrete surface course in the A6 contract section of the highway from Jian sanjiang to Bolshoy Ussuriysky Island and using the infrared thermal imager to study the rule of temperature distribution of bituminous mixture at all construction phases.The relationship between temperature and segregation of the bituminous mixture can be established and the evaluation and the prevention measures of the bituminous mixture temperature segregation can be put forward.The research results can effectively guide the application of infrared thermal imager in all phases of asphalt concrete construction,which has crucial guiding significance for the construction of the bituminous surface course and quality assurance.According to the climatic characteristics of the cold area of Heilongjiang Province,the mix design of the bituminous mixture is carried out,and the high temperature performance is evaluated by the dynamic stability index,the water stability by the residual stability index of the Marshall Immersion test,the impervious performance by the water permeability coefficient.The test result indicates that all aspects of the bituminous mixture satisfy the requirement of the specification.therefore,the mix design can be applied to the construction of the surface course.Utilizing the infrared thermal imager to study the relationship between the photograph distance and the temperature of the bituminous mixture and then the relationship between the photograph distance and the temperature correction coefficient is established.The optimum photograph distance of the equipment is determined at 0.5-1.0m.Utilizing the infrared thermal imager to measure the temperature distribution of the bituminous mixture and to establish the rule of the temperature distribution of the bituminous mixture at all phases of construction.Establishing the relationship of the specimen’s compactness and the temperature by the indoor Marshall test,and using the correlation between the density difference of the bitumen mixture and the temperature difference,the temperature segregation standard is brought up: none-segregation temperature<8 ℃.mild segregation temperature 8~15 ℃.moderate segregation temperature 16~22℃ and severe segregation temperature >22℃.Utilizing the infrared thermal imager to measure the temperature difference between different parts of the bituminous mixture and establishing the relationship between the temperature difference and the void content by sampling and molding the corresponding parts into Marshall Specimen.With 5% of void content as a control index,The temperature difference between the bituminous mixture and the bottom of the carrier shall be greater than 137℃ during the mixing phase;the temperature difference between the internal and the surface temperature of the bituminous mixture shall be less than 13 ℃ during the transporting phase.the temperature difference between the internal and the surface temperature of the bituminous mixture shall be less than 7℃ during the paving phase.the temperature decrease of the bituminous pavement shall be less than 6℃ during the compaction phase.Combined with practical engineering experience,the prevention and control measures of the bituminous mixture against the temperature segregation at all construction phases are recommended,and these measures were applied in the highway from Jiansanjiang to Bolshoy Ussuriysky Island Highway A6 tender,and achieved good results. |
