Compound Rejuvenation of Polymer Modified Asphalt Binder

The objective of this research was to show a way to conduct rejuvenation of aged polymer modified asphalt binder（PMB） successfully.To fully evaluate and understand the rejuvenation of aged PMB,the Penetration grade tests including penetration,soften point,ductility and elastic recovery and SuperpaveTM PG grade tests including DSR,BBR and DDT were conducted.The rejuvenation effect of aged PMB by utilizing a fluid recycling agent in common use for binder rejuvenation was evaluated.And then the compound rejuvenation effect of aged PMB by utilizing the recycling agent with a new modifying additive for binder modification was evaluated.The experimental results indicated that the recycling agent in common use currently does not apply to polymer modified asphalt binder rejuvenation.But the recycling agent together with the modifying additive can restore the characteristics of aged polymer modified binder very well.Therefore,compound rejuvenation of polymer modified asphalt binder is recommended.

Modified Alumina Cement with High Service Properties

This scientific paper gives consideration to the information on the contemporary structure of binary systems and three-component CaO-Al_2O_3-ZrO_2 system required to select rational parameters for the synthesis of cementing agents.The production process of experimental clinker that has a Ca_7Al_6ZrO_（18） composition has been described.The data of X-ray phase analysis and petrographic analysis of the experimental composition of special cement have been given and the reasons for availability of inappropriate phases have been analyzed.The processes of hydration hardening of the cement stone have been studied and the data of differential thermal analysis were used for the establishment of the hydration mechanism for basic crystal phases in the cement clinker composition.The differences in the hydration processes of experimental special cement were analyzed in comparison with known mechanisms.A possibility of the exploitation of special binder in contact with ZrO_2（CaO-stabilized）was tested using the specimens of fine concrete that were subjected to thermal treatment in different modes.The physical and mechanical properties of specimens and the mineralogical composition of concretes were given based on the data of X-ray analysis and the petrographic analysis.The cement additive was selected and its amount in the concrete composition was defined to slow-down the hardening and the mixture plasticization time.The relationships of physical and mechanical characteristics of concrete specimens were defined experimentally as a function of granulometric composition of the filler and thermal treatment temperature.The investigation data of corrosion resistance obtained using the static method were used to find out if experimental concretes can operate in contact with the steel-smelting alkaline slag.

Study on High Temperature Behaviour of Gussasphalt

Rutting is one of the most damages in the asphalt surfaces for the orthotropic steel bridge decks. With Hamburg wheel tracking device, the suitable test conditions for Gussasphalt in Germany are pointed out, the high temperature behaviour of Gussasphalt with different binders are tested and compared. The polymer modified binder has higher resistance stability to rutting. The retained time and mixed frequency have obvious effects on Gussasphalt behaviour during Gussasphalt retained period.

Caltrans use of scrap tires in asphalt rubber products:a comprehensive review

The California Department of Transportation （Caltrans） has been using scrap tire rubber in asphalt pavements since the 1970s in chip seals and the 1980s in rubberized hot mix asphalt（RHMA）. Both the wet （field blend） and dry processes were used in early trials. Caltrans has also used rubber modified binders containing both crumb rubber modifier and polymer modifier that could be manufactured at a refinery facility, a terminal blend wet process. Since the beginning of this century, Caltrans increased the use of scrap tire rubber in paving projects and invested considerable resources in developing technically sound, cost effective, and environmentally friendly strategies for using scrap tire rubber in roadway applications. By the end of year 2010, approximately 31% of all hot mix asphalt （HMA） placed by Caltrans was rubberized HMA, roughly 1.2 million tons. Caltrans efforts in using asphalt rubber products were also demonstrated in its research and technology development. These included the construction of two full-scale field experiments, five warranty projects, and an accelerated pavement study using a heavy vehicle simulator. Additionally, terminal blend asphalt rubber and rubberized warm mix asphalts began to be experimented on trial basis. This paper provides a comprehensive review of Caltrans experience over four decades with asphalt rubber products. Current practices and future outlook are also discussed.