Search

With the rapid increase in the number of vehicles, the use of worn tires that are increasing everyday grows environmental problems. On the other hand, one of the fundamental issues for road agencies is the management and maintenance of the roads. The preeminent practice in this area is to carry out preventive maintenance by methods such as using protective asphalt layers by means of microsurfacing. However, there has not been a study regarding microsurfacing with rubber, the mix design, and its field performance indicators. In this study, the performance of microsurfacing mixtures with different amounts of crumb rubber has been investigated under the ISSA A143 requirement set by the International Slurry Surfacing Association. For this purpose, 0.5–3% of crumb rubber with a grain size of maximum 0.33 mm as a replacement of aggregates has been used. The results from wet track abrasion test excess asphalt by loaded wheel test (LWT), multilayer LWT showed that the best performance among different amounts of rubber powder is obtained at the 14% bitumen emulsion and 0.5% crumb rubber, and the use of this amount of crumb rubber reduced the amount of optimum emulsion needed. Moreover, the rutting on the specimen also decreased compared to the control specimen. [ABSTRACT FROM AUTHOR]

The development of a high-performance waterborne polyurethane modified emulsified asphalt is described in this paper. By measuring the residues of the three major indexes and storage stability, and combining with fluorescence and infrared microscopic analysis, the effect of the ratio of modifier on the stability and the properties of the residue is investigated. Study shows that after adding waterborne polyurethane modified agent, the temperature of the emulsified asphalt reduced susceptibility and the emulsified asphalt has the high temperature stability. The infrared spectrum analysis shows that chemical modification and physical modification coexist at the same time by adding waterborne polyurethane modified agent. [ABSTRACT FROM AUTHOR]

This study is to evaluate the bonding shear stress between asphalt pavement layered structures with emulsion and cutback asphalt as tack coat materials. A simple direct shear test device is set up for testing the shear force of the pavement composite interface. The test results show that the shear force decreases with an increase in temperature. It had a maximum value at optimum application rate and the emulsion asphalt used exhibited higher shear force than that of cutback asphalt. The shear stress model represented by exponential equations between shear stress and temperature is reasonable and is not significantly different to the shear stress from experimental field test, in accordance with the statistic of analysis of variance test. The shear stress modeling developed in this paper provides a valuable method to simulate the shear stress of a different nominal aggregate gradation and tack coat material.

This paper aims at investigating the development mechanism of early-stage strength for cold recycled asphalt mixture using emulsion asphalt. The influence parameters of early-stage strength development for cold recycled mixture by emulsion and cement (CRME) is firstly studied, and then the direct tensile test is used to determine the early-stage strength development law of emulsion asphalt–cement mortar. Lastly, the image analysis is used to identify the fracture morphology of cross-section of cold recycled mixture, and the development mechanism of cold recycled mixture is revealed. The results indicate that the cement plays the predominant role in strength of CRME in first 3 days, while emulsion asphalt plays the predominant role in both early-stage and final strength. Moreover, the adhesion between mortar and aggregate provide the strength for CRME in earth-stage, while the cohesion in emulsion–cement mortar provides the strength for CRME after curing. The findings in the paper provide new approaches to improve the early-stage strength of CRME. [ABSTRACT FROM AUTHOR]

This study is to evaluate the bonding shear stress between asphalt pavement layered structures with emulsion and cutback asphalt as tack coat materials. A simple direct shear test device is set up for testing the shear force of the pavement composite interface. The test results show that the shear force decreases with an increase in temperature. It had a maximum value at optimum application rate and the emulsion asphalt used exhibited higher shear force than that of cutback asphalt. The shear stress model represented by exponential equations between shear stress and temperature is reasonable and is not significantly different to the shear stress from experimental field test, in accordance with the statistic of analysis of variance test. The shear stress modeling developed in this paper provides a valuable method to simulate the shear stress of a different nominal aggregate gradation and tack coat material. [ABSTRACT FROM AUTHOR]