However, BEJs for large joint movements need special performance related accelerated systems tests that provide information about possible risks of failure in practice。 Empa has successfully developed and applied two different types of tests, one for the mechanical re- sistance to rutting from traffic using the MMLS (Model Mobile Load Simulator) and an- other one for the resistance to cracking at cold temperatures due to repeated slow quasi- static joint movements using the Empa-JMS (Joint Movement Simulator)。 These tests are described as follows。
3。2 Rutting performance of large joint movements BEJ using MMLS3
This test is used in the laboratory and in the field for comparing the rutting behavior of a BEJ with a maximum width of 1000 mm at elevated summer-like temperature with the rut- ting behavior of the adjacent standard pavement (typically a mastic asphalt MA) that has been proven rutting resistant according to long term experience。 Testing is done with the Model Mobile Load Simulator MMLS3 (Fig。 5)。 The requirement is that rutting in the BEJ should not exceed rutting of the adjacent standard mastic asphalt which has been selected for its proven positive rutting performance in practice。
The MMLS3 consists of a rigid steel frame of 2'400 mm x 600 mm x 1'150 mm with four adjustable feet。 The load is applied by four pneumatic tire wheels with a diameter of 300 mm and a width of 80 mm, which move like a chain saw in one direction along a ro- tary rail。 The MMLS3 applies a load of up to 2。7 kN on each of its tires that are inflated up to 800 kPa。 The distance between the tires is 1。05 m。 With regard to permanent deforma- tion of BEJ, testing is done at a speed of 0。78 m/s (2250 passings per hour) in order to al- low long tire contact pressure interaction with the BEJ surface。 Depending on the type of movement aids, it may be necessary to evaluate the performance not only in the main driv- ing direction but also in a slight angle to this direction。
In case of field testing, heat is applied to the pavement and BEJ surface with a heating system, which blows hot air across the surfacing of the BEJ underneath the machine from a nozzle attached to a plenum duct along one side of the machine。 On the opposite side a similar nozzle and duct sucks up the air and returns it via an electric heater in a closed loop to the first nozzle。 To ensure an even temperature over the pavement surface, the flow di- rection is reversed every 15 minutes。
For testing in the lab, model system slabs are produced with the maximum design width of the plug joint and tested in a temperature chamber to allow full depth equal temperature of 35 °C。 This is quite severe for the system because it means high temperature even on the bottom of the BEJ。 Profile measurements are made with a profilometer at three different
locations after 60, 2'000, 6'000, 9'300, 15'000 passes。 The selection of the three locations should be such that the influence of the fixations of the movement aids can be determined (e。g。 on top of the L-profile in Fig。 2)。
Wheel Path: 1200mm
Figure 5。 Model mobile load simulator MMLS3 and setup for rutting performance testing。
3。3 Cold temperature movement capacity of large joint movement BEJ using JMS
The Joint Movement Simulator (JMS) is a horizontal stretching bench that consists of two parts: a stationary and a moving part that slides on rails。 One side of the BEJ together with the concrete substrate is firmly fixed on the stationary part, whereas the other side of the BEJ is moved horizontally by a spindle motor in displacement-controlled mode (Fig。 6)。
2600mm 500…1000mm
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