Study On Road Performance And Self-healing Of Semi-flexible Pavement Materials Grouted With ECC Mortar

With the further research and development of pavement materials,the design and construction technology of asphalt pavement and cement pavement in China has made tremendous progress,the overall performance and service life of the pavement have been improved significantly.But in some special sections,like long steep road,tunnel,toll station crossing and road intersection etc,the stable performance,fatigue performance,water damage resistance of pavement materials were put forward higher requirements.However,the use of conventional asphalt mixture or cement concrete in this road section is more likely to lead to a large amount of functional and structural damage.Existing studies have shown that: high-strength pavement materials could be obtained by using high-modulus and high-abrasion resistant materials,but it's difficult to bear on the economic aspect and could not be widely generalized.For such special sections,good performance,economical and reasonable pavement material will still be needed.Obviously,the semi-flexible pavement materials with the characteristics of good high temperature stability,strong durability and less investment is the suitable choice,but its cracking problem has hindered the development and popularization of this kind of pavement to a certain extent.In this thesis,Engineered Cementitious Composites were used to replace the original cement grouting material,and its excellent cracking width control ability?lower water-cement ratio?self-healing ability were utilized to tackle the cracking problem of semi-flexible pavement to some extent.The specific works are as follow:1)Design asphalt mixture gradation with different porosity,and calculate the optimal asphalt dosage of different gradation mixture by leakage test and dispersion test.The test results show that the properties of the parent asphalt mixture meet the design requirements.2)The physical and economic indexes of several common fibers were compared and analyzed,and PVA fibers were selected for the experiment.The influence of water-cement ratio,sand content,fiber content and fiber length on the fluidity of mortar was analyzed.The test results show that the fluidity and strength of the mortar meet the requirements when the water-cement ratio is 0.23,the fiber length is between 5mm~10mm,the content of fiber is 1%~2%,the content of sand is 20%.3)The flexural and compressive tests show that the strength of ECC material increases with the age,and its toughness and structural integrity of the ECC specimens are better than original mortar,as the fiber content increased the flexural strength increased slightly,the crack width decreased,and the compressive strength increased not significantly.The shrinkage deformation of ECC specimen in early-age curing is larger than that of original mortar,and the dry shrinkage strain value is larger.The dry shrinkage strain increases with the growth of early-age curing,but the change tends to be gentle.The dry shrinkage strain with 1% fiber content is the largest,followed by 2%,and finally original mortar.4)Road performance test results show that: ECC mortar and original mortar,as the perfusion materials of asphalt mixture with different porosity,both show excellent high temperature stability,and the dynamic stability increases with the increase of voids,but the semi-flexible pavement grouted with ECC mortar has small deformation and low flow value.The semi-flexible material mixed with ECC mortar has worse crack resistance than SMA-16 asphalt mixture but better than original mortar.ECC mortar has better fatigue performance,and its anti-fatigue performance increases with the increase of void.5)The self-healing test shows that the mechanical properties recovery of the specimens with Micro-cracks under high temperature environment are better than the other two curing conditions.The Fourier transform infrared test and scanning electron microscope test show that the C-S-H and ettringite are the main products generated by secondary hydration in the process of self-healing,the results of filling fractures and self-healing are achieved.