| Cracking phenomenon of asphalt pavement is very common in our country.Crack repair has become one of the main work of highway maintenance department.Using rubber modified asphalt crack filling to repair cracks is one of the effective means to avoid accelerated development of cracks,and is widely used in high-grade highways.At present,although there are many kinds of crack filling products on the market,the quality of crack filling is uneven,which leads to the secondary cracking caused by the early failure of crack filling in asphalt pavement in recent years.And this problem will increase the cost of highway maintenance.Therefore,in order to meet the needs of highway maintenance,it is of great practical significance to develop high-performance crack filling with good repair effect and low cost.On the other hand,the existing performance evaluation system of crack filling is mainly based on empirical method,and the correlation with actual performance needs to be verified,which is not conducive to the selection and quality control of crack filling in engineering practice.Based on the above reasons,starting with the selection and preparation of collagen material for crack filling,the influence of each component of crack filling on its performance was studied in depth.On this basis,the optimum mix ratio of crack filling was determined and its viscosity,strength and resistance to permanent deformation were studied from the perspective of rheology.The main research contents and achievements are summarized as follows:On the basis of a thorough understanding of the preparation process of crack filling,the collagen material for crack filling was optimized,and the optimum mix ratio was determined by orthogonal test,and the influence rule of each component on its performance was obtained.The results show that the content of rubber powder and compatibilizer has a great influence on the cone penetration of crack filling adhesive,while the content of high-viscosity agent and plasticizer has a little influence on the cone penetration of crack filling adhesive,and the influence range on the cone penetration index of crack filling adhesive is arranged from large to small as follows: compatibilizer > Rubber Powder > plasticizer > high-viscosity agent;for softening point index,the four factors have little difference,from large to small row.It is listed as follows: rubber powder > high viscosity > compatibilizer > plasticizer;for ductility index,the content of rubber powder,high viscosity and compatibilizer has a greater impact on it,while the content of plasticizer has a smaller impact on it,and the influence range can be arranged as follows: high viscosity > Rubber Powder > compatibilizer > plasticizer.According to the cone penetration test,softening point test,flow test,elastic recovery test and low temperature tension test in the existing performance evaluation system of crack filling,the optimum mixing ratio of low temperature,common and high temperature crack filling adhesives was determined to be the eighth,eleventh and sixteenth groups of orthogonal test,respectively.According to the existing performance evaluation system of crack filling(cone penetration test,softening point test,flow test,elasticity recovery test and low temperature tensile test),the optimum mix ratio of crack filling is determined as follows: low temperature type: 10% rubber powder,4% SBS,4% high viscosity agent,6% compatibilizer,1% plasticizer;common type: 15% rubber powder,4% SBS,3% high viscosity agent,2% compatibilizer,1% plasticizer;high temperature type: 20% plasticizer;Rubber powder,4% SBS,4% high viscosity,2% compatibilizer,1.5% plasticizer.Flow scanning and peak holding test,temperature frequency scanning test and multiple stress creep recovery test were carried out with dynamic shear rheometer.Viscosity,strength and resistance to permanent deformation of crack filling were studied respectively.(1)The dispersion degree of viscosity measured by peak retention test at 60 C and 0.50 rad/s is small,which can better distinguish the viscosities of different crack filling adhesives.The viscosities of three asphalts and six crack filling adhesives are arranged as follows: M3 > M2 > M1 > C > B > SBS modified asphalt > rubber asphalt > base asphalt.The average viscosities of six grouting adhesives are 1780.0Pa.s,11.8 times of base asphalt and rubber.Rubber asphalt 7.0 times and SBS modified asphalt 3.5 times.(2)The CAM model is used to fit the principal curve of the complex shear modulus of the crack filling.The range of the complex shear modulus of the crack filling varying with the angular frequency is smaller than that of the base asphalt,and its temperature sensitivity is lower than that of the base asphalt and rubber asphalt.The complex shear modulus of crack filling in low frequency range is larger than that of base asphalt and rubber asphalt.The complex shear modulus of crack filling in high frequency range is close to that of rubber asphalt.It shows that the ability of crack filling to resist permanent deformation and fatigue cracking at high temperature is better than that of base asphalt and rubber asphalt.On the whole,the strength of crack filling is higher.(3)MSCR test showed that the irrecoverable flexibility of six kinds of crack filling was significantly lower than that of base asphalt,while the recovery rate of deformation was significantly higher than that of base asphalt.With the increase of stress level from 0.1 kPa to 3.2 kPa,the index increases while the index decreases,which makes it easier to produce permanent deformation.The index of crack filling increases with the increase of temperature,while the index decreases.With the increase of temperature,the crack filling softens gradually,and the deformation recovery ability decreases,which makes it easier to produce permanent deformation.Compared with the commercial crack filling,the penetration and viscosity of the prepared crack filling are relatively small,which is related to the unsatisfactory stirring effect in the laboratory.The softening point,elastic recovery rate,fluidity and resistance to permanent deformation are not significantly different.Generally speaking,the prepared crack filling has good working performance and achieves the development goal.Finally,the influence of construction ageing on the properties of crack filling is analyzed by indoor simulation test.The results show that there is a certain amount of light oil volatilization in the construction process leading to ageing,which makes the taper penetration and softening point of crack filling decrease in varying degrees,but the fluidity and elastic recovery rate have no obvious change rule,which may be due to the composition distribution of different crack filling.There are differences in ratio and production technology. |
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