Application of organically modified calcium sulfate whiskers in asphalt modification
To obtain the modified asphalt with better mechanical properties and improve the pavement performance of tradi-tional matrix asphalt,the application of organically modified calcium sulfate whiskers(CSW),prepared from phosphogyp-sum,in asphalt modification were systematically studied.Through the materials preparation,analysis and testing,as well as mixture testing,changes of the three main indexes,apparent viscosity,and high-temperature performance of asphalt before and after modification using phosphogypsum and organically modified CSW were analyzed.Furthermore,the pavement per-formance of different bitumen mixtures was explored.The results indicated that the organic modifiers were mainly acted on the surface of CSW in the form of chemical adsorption.The whisker materials modified with combined organic modifiers were more compatible with asphalt.The introduction of organically modified CSW enhanced the bonding strength between asphalt and whiskers to a certain extent and improved the high-temperature stability,however,its low-temperature perfor-mance had been relatively reduced.The results were confirmed furthermore by the Marshall stability tests,freeze-thaw split-ting tests,and wheel tracking tests.The water stability and high-temperature stability of the modified asphalt mixtures by phosphogypsum or organically modified CSW were better than those in matrix asphalt,and the pavement performance of the asphalt modified by organically modified CSW became better.
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