Exploration On Modification Technology And Mechanism Of Paving Asphalt

Rapid development in economy and significant growth in living standard caused a sharp automobile population increase in recent years, which raised higher request for road quality. Improvement of road quality mainly depends on the preparation of modified asphalt with blending petroleum asphalt(PA) and modifier to meet the requirements of high grade road. Coal tar pitch(CTP) and crumb rubber(CR), as PA modifier widely used at home and abroad, can both enhance asphalt road performance and alleviate environment pressure.Two kinds of PA materials and mid-temperature CTP materials are selected to prepare CTP modified asphalt(CTPMA), and two kinds of CR materials are used to prepare CR modified asphalt(CRMA) blending with PA materials in this paper. Effect such as modifier ratio, particle size, stirring method and temperature on modified asphalt properties are deplored to determine the preparation technology, including penetration, softening point, ductility and aging test. Results show that proper technology of CTPMA preparation is 15% CTP ratio, 60 mesh to 80 mesh particle size and 125 oC with shearing stirring method, while proper technology of CTPMA preparation is 10% CR ratio, >80 mesh particle size under 190 oC stirring temperature. With CTP or CR added in, properties such as isoviscous temperature, anti-aging and harness are improved, by contrast, anti-tensile property is declined. Compared road performance of CTPMA with CRMA, it can be concluded that CTP is more suitable for being PA modifier.Matlab tools are applied to calculate performance index of modified asphalt with logic programming according to least square method. Outcomes indicate that high temperature property of modified asphalt increased while temperature sensitivity and low temperature properties decreased with adding CTP or CR to PA. In addition, TG-DSC, group analysis and IR analysis of asphalt samples are introduced to deplore substance change during modified process in this paper. It can be inferred that low molecular mass substance tend to form higher molecular weight substance centered on Resins. And the results also show that besides simple physical change, chemical reaction is also demonstrated during modified process under the technology condition in this paper, such as dehydroxylation reaction, carbonyl group pyrolysis reaction and poly condensation reaction of aromatic rings.