Pavement performance and application of anion rubber-modified asphalt

HONG Wei 2 LI QingShan 2 GUAN GuoQuan 1 LIU Jun 2 SUN Jing 0 XING GuangZhong 2 0 English Department, Foreign Languages College, Yanshan University , Qinhuangdao 066004, China 1 Hesen Chemical Technology Co. , Ltd., Chengdu 610072, China 2 State Key Laboratory of Metastable Materials Science and Technology, Yanshan University , Qinhuangdao 066004, China We have used a unique process to develop the first successful anion rubber modified asphalt mixture. Rubber and asphalt are used in equal proportions in the mix. Compared with conventional asphalt, the anion rubber modified asphalt show better pavement performance, and fully met the relevant specifications. The dynamic stability and failure strain indicators are better than those of SBS modified asphalt. Compared with traditional rubber modified asphalt, the amount of waste tires incorporated into this new rubber modified asphalt is much greater; the new asphalt also improved the air quality near the road, thus providing great economic and social benefits. With the rapid development of the Chinese auto industry and increasing quality of life, car ownership is increasing and we are facing the problem of dealing with many waste tires. The statistics show that the total amount of waste tire in China in 2011 is 2.5278 million tons, and by 2012, it is expected to reach 2.8451 million tons [1]. Such a huge amount represents a heavy social and environmental burden. The main measures for dealing with this problem at present include stacking (or tamping), burning and recycling. The application of crumb rubber in road construction has become a focus of research and development globally; it is also one of the best choices for dealing with huge numbers of waste tires [2,3]. Anion rubber-modified asphalt 100# matrix asphalt was obtained from Asphalt Company, The matrix asphalt was prepared to the liquation stage, and the rubber powder was dehydrated. The two were combined in an appropriate ratio (we used a high proportion modified adulteration technique, so the proportion of rubber to asphalt can reach up to 1:1), and churned until well mixed, followed by heating up to 180C. The mixture was then homogenized for 30 min at a temperature of 170190C and a speed of 40006000 r/min using a high shear scattered emulsifying machine. Then the required amount of anion additive was added, followed by blending for a further 30 min. The mixture was cooled to 16010C, and stood for 30 min to give the anion rubber-modified asphalt. The Author(s) 2012. This article is published with open access at Springerlink.com Fourier Transform infrared spectroscopy (FTIR) Figure 1 shows the FTIR spectra of the anion additive, rubber modified asphalt and anion rubber modified asphalt. The characteristic peak at 3425 cm1 is the stretching vibration absorption band for OH, and depends upon the HOH angle. The two peaks characteristic of the anion additive appear strongly in the spectrum of anion rubber modified asphalt, and are absent in that of rubber modified asphalt. This indicates that the anion additive exists stably in the anion rubber modified asphalt. No new peaks emerged [4,5]. The above analysis indicates addition of anion additive into rubber-modified asphalt is a physical admixing process. There are only Van der Waals forces between the components, and new functional groups are not generated. In addition, because the particle diameter of the anion additive is at the nano level, the miscible system is uniform and stable, and thus suitable for production. 2 Anion Rubber modified asphalt performance testing Test items, standards and equipment Testing of the asphalt, including designing the proportions of the mixture, evaluating its properties and evaluating its road capability was carried out in accordance with Standard Test Methods of Bitumen and Bituminous Mixtures for Highway Engineering (JTJ052-2000) and Technical Specifications for Construction of Highway Asphalt Pavements (JTG F40-2004). We then evaluated the anion release performance [68]. The equipment used in the experiments is given in Table 1. Anion rubber modified asphalt mixture ratio design (1) Grading of mineral aggregate. In this experiment the mineral aggregate gradation type is AC13, as shown in Table 1 Main Instruments and Equipment Figure 1 The FTIR spectra of anion additives, rubber modified asphalt and anion rubber modified asphalt. 1, Anion additives; 2, rubber modified asphalt; 3, anion rubber modified asphalt. Table 2. (2) Marshall compaction test of anion rubber modified asphalt mixture. This test uses the standard Marshall compaction method (T0702-2000) to determine the asphaltaggregate ratio of the asphalt mixture. The sample is compacted 75 times on two faces at a compaction temperature of 165C. The gross volume of asphalt mixture is determined using the wax seal method, and the theoretical maximum density (dry density) is determined using the vacuum law. The paraffin density is 0.87 g/cm3, and the test water temperature is 20C. Anion rubber modified asphalt mixture Marshall compaction test results and compaction curves are shown in Table 3 and Figure 2. (3) Determining the optimum asphalt-aggregate ratio for anion rubber modified asphalt mixture. To determine the best asphalt-aggregate ratio for anion rubber modified asphalt mixture, a comprehensive analysis was performed to find the asphalt-aggregate ratio corresponding to maximum density, minimum VMA (voids in mineral aggregate) and Instrument manufacturer Table 2 AC13 Gradation Sieve mesh (mm) Cumulative pass rate (%) Marshall compaction test results for anion rubber modified asphalt mixture Marshall test curves for anion rubber modified asphalt mixture. VCA (percent air voids in coarse aggregate). Asphalt-aggregate ratio corresponding to the maximum dry density: OAC1=6.38%; Asphalt-aggregate ratio corresponding to the minimum VMA: OAC2=6.38%; Asphalt-aggregate ratio corresponding to the minimum VCA: OAC3=6.38%; Optimum asphalt-aggregate ratio of anion rubber modified asphalt mixture: 6.38%. 2.3 Evaluation of anion rubber modified asphalt pavement performance Evaluation of anion rubber modified asphalt pavement performance was performed under the optimum asphaltaggregate ratio conditions [912]. (1) High-temperature rutting test. Under the requirements of Highway engineering asphalt and asphalt testing procedures (JTJ052-2000), the wheel grinding method was used in making track plate specimens with the size of 300 mm 300 mm 50 mm, after which process their dynamic stability were determined. The test results are in Table 4. Dynamic stability is an indicator which reflects the resistance of the asphalt mixture to permanent deformation at high temperature, and is more intuitive than the Marshall Stability Index. The higher the asphalt mixture dynamic stability, the stronger its rutting resistance and the better its stability at high temperature. Table 4 shows that anion rubber modified asphalt mixture ha (...truncated)