Analysis on On-Site Asphalt Pavement Quality Inspection Technology in Highway Engineering

The acceleration of urbanization has promoted the increase in the number of urban highway projects,resulting in an increase of emphasis on the quality of urban highway projects.The quality and safety of highway construction directly affects the driving comfort,safety,and service life after it is put into operation.Among them,asphalt pavement is an important structure in highway construction,and it is also a key link that directly affects the construction quality.In order to ensure the quality of construction,it is necessary to strengthen on-site testing during the construction process to discover problems in time,and to ensure that the construction is up to standard.This paper mainly presents an analysis on the necessity and application of on-site quality inspection technology for asphalt pavement construction of highway engineering,and outlines measures to improve highway engineering construction testing technology.

Discussion on Test and Detection Technology of Highway Asphalt Pavement

The road traffic industry in China has been developing rapidly in recent years.Asphalt has become the main material in road construction because of its seamless connection and short construction period,and it has an important impact on the overall quality of highway construction.Therefore,it is necessary to conduct scientific and reasonable tests and detections for highway asphalt pavement.This paper presents a discussion on the test and detection technology of highway asphalt pavement for future reference.

Mixing ratio design of emulsified asphalt cold recycled mixture based on gyratory compaction molding

In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting strength, stability and water stability test;the design of the experiment involved changing gyration number, emulsified asphalt and water content, molded specimen temperature and other factors to analyze the volume parameters, mechanical properties and water stability. The results show that both the maximum dry density and dry and wet splitting strength ratio(DWSSR) of emulsified asphalt cold reclaimed mixture are improved by the rotary compacting method, while the porosity and the optimal dosage of water are reduced. Furthermore, with the increase of compaction times, the porosity and splitting strength index both change exponentially. DWSSR and porosity are consistent with quadratic functions. The use of gyratory compaction for 70 times at 25 °C and the optimum dosage of emulsified asphalt can be determined based on the splitting strength ratio. The high-temperature stability and water damage resistance of the pavement can be improved by the use of rotary compacting method effectively, and the early strength and road performance are higher than the regulatory requirements.

Measuring crack propagation in reinforced asphalt concretes

Two different reinforcing methodologies are applied：modification of the overlay characteristics by adding chopped glass fibers to the hot mixture asphalt （HMA） and reinforcing asphalt overlay with glass grids.Theory of fracture mechanics （FM） is employed to determine crack growth rates for the suggested anti-cracking overlay systems.Asphalt mixture designing tests,three point bending tests and fatigue crack propagation tests were carried out.The critical stress intensity factors KIC are determined for plain and reinforced asphalt concrete.Depending on the fatigue crack propagation,the crack growth rate is determined for each type of anti-cracking system and the cracking process is also analyzed.One of the significant points in this study is the attempt to give better understanding of the crack propagation for multilayer asphaltic overlay or what are suggested herein to be called composite structure anti-cracking overlay system.The results indicate that the reinforcing materials improve anti-cracking characteristics of the asphalt concrete.Composite structure anti-cracking overlay gives a good solution for the reflective cracking phenomenon over old cracked pavements.

The Development of Recycling Agent for Asphalt Pavement

A type of recycling agent was developed and its use for modifying used asphalt is described.The results show that the viscosity and three main properties of the aged asphalt were remarkably improved.With 5% - 7% content of recycling agent, the main properties of recycled asphalt comported with China GB asphalt standard AH-70 and the recycled asphalt concrete could be used as high grade highway.Furthermore,the recycling mechanism of the aged asphalt is discussed.

Interaction study of permafrost and highway along Qinghai-Xizang Highway

Eight monitoring sites are set along the Qinghai-Xizang Highway (QXH) to investigate the characteristics and process of interaction between permafrost and highway, including the up-per and down boundaries of active layer under natural surface, seasonally freezing-thawing depth under asphalt pavement, permafrost table temperature and roadbed stability. The investigation results show that the changes of active layer thickness and permafrost table temperature under asphalt pavement are greater than these under natural surface due to the absorbing heat action and less evaporation of asphalt pavement, as a result, the engineering geological problems such as thaw settlement and frost heave present frequently along QXH line and produce the adverse impact on roadbed stability.

“Streets of Fire”revisited:contact burns

Background:Pavement-street contact burns are rare.This study compared recent contact burns to those published in“Pavement temperature and burns:Streets of Fire”in 1995.The hypothesis was that there were a significantly increased number of pavement-street burns,as a result of increased ambient temperatures,and that motor vehicle crash(MVC)contact burns were less severe than pavements-street burns.Methods:This was a retrospective burn center registry study of naturally heated surface contact burns during May to September from 2016 to 2018.Statistical analyses were performed with one-way analysis of variance(ANOVA)and Maximum Likelihood chi-squared for age,percent of total burn surface area(%TBSA),treatment,hospitalization,comorbidities,hospital charges,mortality,ambient,and surface temperatures(pavement,asphalt,rocks).Results:In the 1995 study,median ambient temperatures were 106(range 100–113)°F compared to the 108(range 86–119)°F highest noon temperature in the current study.No ambient temperature differences were recorded on days with pavement burn admissions compared to days without these admissions.There were 225 pavement,27 MVC,15 road rash,and 103 other contact burns.The major injuries in the pavement group were due to being“down”(unknown reason),falls,and barefoot.Compared to the others,the pavement group was older,56+years,p<0.001,and had smaller burns but similar length of stay.Fifty percent of the 225 pavement group patients with full-thickness burns required skin grafts.There were 13(6%)fatalities in the pavement group vs 1(4%)in the MVC group,p=0.01.Fatalities were secondary to sepsis,shock,cardiac,respiratory,or kidney complications.Compared to survivors,the non-survivors had a significantly higher%TBSA(10%vs 4%),p=0.01,and lower Glasgow Coma Scores(10 vs 15),p=0.002.Conclusion:There was a median 2°F increase in ambient temperature since 1995.The increase in pavement burn admissions was multi-factorial:higher temperatures,population,and the number of older patients,with increased metropolis expansion,outreach,and urban heat indices.Pavement group was similar to the MVC group except for significantly older age and increased mortality.Morbidity associated with age contributed to increased mortality.