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Flow resistance @ 60 °C 63 mm EN 13880-5: 2004
Resistance to heating
– Aging the binder according to EN 12607-3, 5 h @ manufacturers heating temperature
– Recovery with ductilometer @ 0 °C after aging
Lost weight 61% EN 12607-3: 1999 Lo P150 mm
ERD P75%
DERD 615%
Dynamic viscosity – EN 13702-2: 2003
Dynamic complex modulus
– Temperature: —10–60 °C
– Frequency: 0。125–8 Hz
– Coaxial shear test
Polymer dispersion – EN 13632: 2003
Polymer content – GPC
ERD: Elastic recovery in ductility; DERD: Change of ERD before and after heating; GPC: Gel permeation chromatography。
bitumen produced a blended binder with excellent performance at low and high tem- peratures for APJs。 Crumb rubber powder and granules can be successfully used to prepare bituminous joint materials with excellent performance and lower cost [34]。 In most of the cases, polymer modified bitumen binder with high polymer con- tents are used。 Due to the addition of large amount of polymer and filler, the viscos- ity of the modified binder is much higher compared with traditional asphalt binders used for asphalt pavements。 Hence, apart from low temperature flexibility and flow resistance at high ambient temperatures, the fluidity for the installation process is also important。 The binder must have the capacity to fill the voids between coarse aggregates in the joint。 Viscosity test can be used to evaluate the workability of the binder。 The use of warm mix additive could be interesting to reduce the viscosity of the binder and thus allows improving the workability or lowering installation tem-
perature to reduce thermal aging [35–37]。
The asphalt binder used for APJs shows temperature and time dependent mate- rial behaviors。 The temperature dependence is considered to be a primary indicator and the time dependence is a secondary contributor to the joint performance。 The asphalt binder becomes soft at high temperatures and thus is susceptible to rutting and permanent deformation。 As temperature drops, the asphalt binder becomes stiffer, loss of ductibility and relaxation。 Glass transition temperature, Tg was pro- posed as an indicator of binder temperature dependence as well as low-tempera- ture performance [9,11,37]。 Above Tg the binder behaves like a ductile solid or highly viscous liquid while it behaves as a brittle solid below Tg。 APJs should not be installed at locations where the extreme low temperature is lower than the Tg of the binder。 Research done by Soiman indicated that Tg of bituminous sealants can be well determined from data obtained from dynamic testing by using the peak of loss modulus-temperature curve [38]。
The fundamental behavior of APJ is to relax or dissipate the joint stress that is created by temperature-induced motion and bear repeated traffic loads。 Bridge joints are exposed to deformations as bridges expand and contract due to temper- ature changes。 The joint stress is displacement-induced effects that occur at a very low rate。 If the joint stress could relax at a rate nearly equal to the one that temper- ature-induced motion creates the stress, no or only small stresses would build up in the joint material and the materials flow accommodates the joint deformation。 Bin- der relaxation is very important, especially at low temperatures to avoid the stress accumulation。 Furthermore, high elongation at break is also important to deal with joint movements。 It can be concluded that the flow and relaxation of binder is important at low temperatures。 However, the disadvantage is that the joint cannot be free from rutting at high temperatures。 Thus the contradiction between low and high temperature properties should be well considered for material design and development。 Soft base bitumen modified with high amount of polymer is of interest。