Application Research On Rapid Testing Technology Of Compaction Quality For Subgrade And Semi-rigid Base Based On PFWD

Aiming at the shortcomings and limitations of existing test technologies for the compaction degree and bearing capacity of subgrade and pavement,and relying on the road construction project in Yaohai District,Hefei City,Anhui Province,the application researches are carried out on the rapid testing technology for compaction quality of subgrade and semi-rigid base with Portable Falling Weight Deflectometer(PFWD)to expect to provide a scientific basis for the rapid non-destructive testing and evaluating the compaction quality and bearing capacity of structural layers during the construction of asphalt pavement.1)The comparisons between the PFWD and the traditional test methods show that the PFWD technology has the advantages of rapid,non-destructive and wide test field etc.At the same time,the PFWD equipment is high In stability,and its effective action depth of impact load meets the control requirement of compaction layer thickness.It shows that the PFWD is applicable for rapid testing during the construction of subgrade and semi-rigid base.2)The subgrade soil in the support project is the low liquid limit clay CL,and it is more sensitive to humidity.After the treatment of mixing lime,the problem,which the soil is not easy to be compacted as the higher water content,is effectively solved.Accordingly,through the comparison testing in laboratory and field,the empirical relationships between the PFWD modulus and the compaction degree as well as the water content for the subgrade soil samples and the subgrade were established,respectively.Meanwhile,the compaction control standards were converted into the modulus control standards in accordance with the field empirical formula.The engineering applications and verifications show that the PFWD is applicable for the compaction quality control during subgrade construction.3)Through the laboratory testing,the growth laws of the PFWD modulus with the maturity of cement stabilized macadam specimens under the different curing conditions were compared and analyzed,and the inverse exponential relationships between the PFWD modulus and the maturity were established.The results show that the temperature is one of the important factors effecting the modulus growth rate.At the same time,through the comparison testing of semi-rigid base in the construction site,the power function relationships between the PFWD modulus and the compaction degree were established.Furthermore,the compaction control standards were converted into the modulus control standards,and the field testing during construction were carried out.It indicates that the PFWD is applicable for the compaction quality control during semi-rigid base construction.4)Through the comparison testing after construction on lime soil subgrade,lime soil subbase and cement stabilized macadam base,the power function relationships between the corresponding PFWD modulus and the BB deflection were established,respectively.Accordingly,the acceptance standards of deflection were converted into the acceptance standards of PFWD modulus,and considering the curing age correction of PFWD modulus for the cement stabilized macadam base,the acceptance testing of construction quality in the support project were carried out.The results show that the PFWD is applicable for the construction quality acceptance in the subgrade and semi-rigid base.In summary,the researches of the thesis have the important practical significance and engineering application value for improving the construction quality and long-term performance of asphalt pavement.