The Development And Application Research On The Modified Multigrade Asphalt Cement Technology

Over the last decade, with the increasing volume of traffic that is driven by the rapid development of the national economy and the highway network, higher performance of the asphalt mixture and raw materials (asphalt and aggregate) are required because ordinary paving asphalt is unable to meet the high-strength, stability, security and durability requirements. Modified asphalt has become the principal means to increase the performance of asphalt and asphalt mixture. The disadvantages of currently used modified asphalt in China which mainly is multi-polymer modified asphalt that belongs to physical modification are the lower hot-storage stability, segregation, complex processing and higher cost. Find a good stability, outstanding performance, cost-effective modified asphalt is the main purpose of this work.Based on the study of Mechanism of modification, we developed new modified asphalt named MAC which is of chemical modification as to improve asphalt performance by forming fiber network caused by modifier's chemical reaction. Molecular structure is changed after modification that shows stable performance without any segregation. It's high-temperature viscosity is 10 times more than ordinary asphalt and 2 times of SBS as well as enhance the cohesive force of the asphalt effectively. The evaluation of SUPERPAVE system shows that its high temperature PG grade is improved from 64 to 76 as well as keeping low temperature PG grade stable at -22. Through a large number of lab tests and practice, we studied the basic performance of MAC and its performance used as gel and proposed "the workmanship of manufacturing MAC in lab" and "the workmanship of manufacturing MAC at workshop" without any domestic chemical modified asphalt technical standard and materials.By mixing MAC modified asphalt with different percentage rubber powder into AC-20 asphalt mixture and SMA-13 asphalt mixture and studying its performance through tests such as, volume index, high temperature performance, water stability, low-temperature bonding Performance tests , we studied the feasibility of mixing rubber powder into the MAC modified asphalt mixture and evaluated the percentage of rubber powder.Based on the multi-grade stone-to-stone theory of aggregate, we proposed the reference grade range of LSPM with MAC in which improved high temperature stability and drainage properties; set up the design method of LSPM that is controlled by the index as asphalt film thickness, design air voids, leakage and Cantabro test as well as confirmed by stability test using 8cm～12cm rutting plate .Preliminary study the performance of LSPM including high-temperature stability test, water stability test, mechanical properties and permeability tests on MAC modified asphalt for LSPM. We investigated the technical requirements of MAC using in LSPM.Finally, paving the trial to study systematically the field performance of MAC modified asphalt for LSPM. After 3 to 4 years vehicle loading, the measured data show that the LSPM with MAC has good performance of high-temperature permanent deformation resistance and reflective cracking resistance.