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To quantitatively evaluate the thermal stability and combustion characteristics of asphalt, the tests of constant temperature heating, oxygen index and cone calorimetry were used to obtain mass loss, oxygen index, heat release rate (HRR), total heat release rate (THR) and mass loss rate (MLR) of two asphalts of base asphalt and rubber asphalt. The results show that at the identical temperature, the mass loss, oxygen index, peaks of HRR, THR and MLR of rubber asphalt and the value of mass loss rate increased with the increasing of temperature are higher than those of base asphalt, while the thermal stability and combustion characteristics of rubber asphalt are inferior to base asphalt. Comparing three tests, the cone calorimetry test results are more reliable because of its more parameters, which is recommended to evaluate thermal stability and combustion characteristics of asphalt. [ABSTRACT FROM AUTHOR]

The warm-mix flame retardant composite modified asphalt was prepared with warm-mix agent (Sasobit), aluminum hydroxide (ATH), organic montmorillonite (OMMT) and base asphalt, and fourier transform infrared (FTIR) scanning, thermogravimetric (TG) analysis and differential scanning calorimetry were used to investigate the coordination and synergistic effect of warm-mix agent and flame retardant and the flame retardant mechanism. The results show that the modification effect of warm-mix agent and flame retardant on the base asphalt is mainly physical modification. The addition of flame retardant can improve the thermal stability, flame retardant and smoke suppression effects of asphalt, and the flame retardant, smoke suppression effects are improved with the increasing of the amount of flame retardant. The flame retardant can form barrier coating on the asphalt surface with wrapping effect, which can effectively reduce the heat flow rate with excellent flame retardant efficiency and combustion process control ability. The compounded flame retardants of ATH and OMMT can provide the synergistic flame retardant effect, and the flame retardant mechanisms are mainly heat exchange interruption and condensed phase flame retardant. When the compounded flame retardant content is 8%, the asphalt has good flame retardant and smoke suppression properties with good economy. [ABSTRACT FROM AUTHOR]

This paper investigates the mechanism of foaming water on asphalt adhesion and cohesion using a combination of macro and microscopic methods such as molecular dynamics simulations, water boiling tests, surface free energy tests and pull-out tests. The results show that water molecules repel asphalt molecules on the molecular scale-thus weakening the interfacial energy between asphalt; on the macroscopic scale, it is found that the anti-boiling spalling of foam asphalt and aggregate is reduced, the foaming water is detrimental to the adhesion and cohesion of asphalt, and the more foaming water there is, the more obvious the damage to the adhesion and cohesion of asphalt. The interfacial energy of foam asphalt is highly correlated with its cohesive and adhesive properties, and the multi-scale effects of foaming water on the cohesive/adhesive properties of foam asphalt can be explained at macroscopic and microscopic molecular scales. [ABSTRACT FROM AUTHOR]

To explore the rheological properties of warm-mixed flame retardant asphalt, warm agents (Sasobit), aluminum hydroxide and organic montmorillonite were added respectively into the 70# matrix asphalt and SBS modified asphalt to prepare two types of modified asphalt. The influence of flame retardant content on the high and low temperature performance of the warm-mixed flame retardant asphalt was analyzed by the dynamic shear rheometer test, bending beam rheometer test and multi-stress creep recovery test. The results show that with the increasing of flame retardant content, complex modulus, rutting factor, strain variation percent recovery and stiffness modulus value are increased gradually, while non-recoverable creep compliance and creep rate value are decreased. The flame retardant can improve the high temperature performance and impair the low temperature performance of the asphalt. Through comprehensive evaluation of high and low temperature rheological properties and economy, the optimal proportion of compound flame retardant is recommended to be 8%. [ABSTRACT FROM AUTHOR]

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