Updating Bituminous Stabilized Materials Guidelines Mix Design Report Phase II

APPENDIX J
Technical Memorandum
Updating Bituminous Stabilized Materials
Guidelines: Mix Design Report, Phase II
Task 10: Moisture Sensitivity: Part II (Validation)
Final Report: Sept 2008
AUTHORS:
KJ Jenkins
J van der Riet
ME Twagira
1

1. BACKGROUND AND INTRODUCTION
1.1. Terms of Reference
Moisture ingress has a detrimental influence on BSMs, both in terms of stiffness and strength of
the material. In order to develop more reliable laboratory testing techniques, a more robust link
between laboratory properties of the material and field performance needs to be established.
Accelerated Pavement Testing (APT) with devices such as the MMLS3 can serve to provide that
link.
The advantages of APT testing include the evaluation of a range of variables in a relatively short
period of time. This is particularly applicable to BSMs because ranges of different types of
binders used in practice, namely:
• Emulsion
• Emulsion and Cement
• Foam Bitumen
• Foam Bitumen and Cement
Each of these binders, along with the aggregates, reacts differently to exposure to moisture.
The knowledge and understanding of the mechanisms of moisture damage and the main factors
influencing the deterioration need further extension. In addition, reliable limits need
establishment for tests on materials exposed to moisture. Variables such as binder types,
aggregate types, active fillers, compaction, curing, manner and harshness of moisture exposure,
as well as the impact on material properties, requires investigation.
1.2. Task Objectives
In terms of the findings of the Inception Study report, the objectives of Task 10 were to:
• Investigate accelerated pavement testing procedures using an MMLS3 on various
Bituminous Stabilised Materials (BSMs) including moisture exposure,
• Investigate the performance of the BSMs above with water exposure, using wheel
tracking tests, and
• Validate the behaviour of the selected durability/moisture sensitivity test method
outlined above with the results of the accelerated tests.
• Make appropriate recommendations regarding the use of the APT device on the
screening BSMs based on the moisture related damage.
Task 9 has outlined the development of the Moisture Induced Sensitivity Test (MIST) apparatus
that developed for the conditioning of triaxial specimens for the evaluation of the resistance to
moisture of these materials. The objective of Task 10, in short, is therefore to validate the
2

findings of the moisture damage that observed through MIST conditioning. The setting for
loading pulse duration and pressure of the MIST apparatus was influenced by the load duration
and stresses of the wheel loads applied to the materials by the MMLS3 APT device. Therefore, a
rational analysis should be possible.
1.3 MMLS3 Accelerated Pavement Testing device
The scaled testing of pavement structures and surfacing is becoming a standard in the industry.
This is due to the advantages associated with evaluating and grading of the asphalt mixes
proceeding to construction, (Walubita et al., 2002). The development of the Model Mobile Load
Simulator Mk3 (MMLS3) contributes significantly to Accelerated Pavement Testing (APT)
method. The performance prediction of a pavement tested for rutting, fatigue, and susceptibility
to moisture damage is possible. All of these failure mechanisms can be evaluated in the field i.e.
under full-scaled conditions or in a laboratory under controlled conditions. In the laboratory, all
the variables that have an influence on the properties of the pavement materials can be
controlled during MMLS3 testing. The need for the development of standardised test protocols
for testing BSMs with the MMLS3 arises to make certain that the result that produced is
reasonable and comparable. A standardised testing platform ensures uniformity in results and
increases the confidence in the results.
The MMLS3 consists of four axles and each axle has a 300mm diameter inflatable pneumatic
wheel on it that circulates in a vertical closed loop. The wheels are supported in bogies that
linked by a continuous chain. The wheels are powered by an electric motor that drives a drum,
which draws the wheels over the testing bed. The MMLS3 can also apply lateral displacement
(wander) of plus or minus 80mm around the central axis.
The four wheels are loaded by means of a swing-arm and a spring. The four wheels exert the
load on specimens underneath the MMLS3. The speed of the wheels controlled at maximum of
2.5m/s, which is equal to 7200 wheel loads per hour. The testing conditions are controlled, and
it is possibility to do tests at temperatures within a range of 0ºC to 60ºC. Figure J.1 provides an
illustration of the MMLS3 test set-up.
Figure J.1: MMLS3 in testing mode
3

The briquettes for the test are secured in a steel beam. The briquettes are supported in the
lateral direction by moulds that provide the circumferential support in the test bed. Confinement
pressures applied on both longitudinal and transverse direction.
The steel beam or test bed can accommodate up to nine briquettes. The briquettes are laterally
supported by separate aluminium moulds with a width of 110mm. The moulds allow free
movement of the lateral support for individual briquettes. The mould set-up is placed in a steel
bath that is filled with water. The water bath can be filled to any level including a level that the
briquettes completely covered with water. The bath is connected to thermal water pump that
can be set to keep the water to a specific temperature. To measure the temperature of the
water and briquettes, a thermocouple placed in between two briquettes while it is being set-up.
The temperature can then be monitored throughout the whole test. The Figure J.2 shows a
graphical image of the test bed.
Figure J.2: The briquettes placed in the test bed.
Before MMLS3 trafficking, the surface profile of the briquettes are measured by a profilometer.
The profilometer used to measure the change in surface profiles (deformation) of the briquettes
before and after testing. The profilometer, in Figure J.3, connected to a computer that plots a
graphical image of the profile and saves the data as well. The profilometer rolls a sensor, as
shown in Figure J.4, over the surface of the briquettes and measures the vertical displacement
at 2mm intervals.
Figure J.3: The Profilometer busy measures the briquettes.
4

Figure J.4: The measuring wheel of the Profilometer roll on surface of briquette
The profilometer is placed on the index bars when measuring the surface of the briquettes. The
index bar is there as a reference for future readings on the same briquette, see Figure 3.
The first profile measurement taken on each briquette before any load application, this is the
zero reading before any deformation. After each loading interval, the height of the briquettes is
measured. The deformation readings are stored electronically. The readings of all the intervals
of one definite briquette plotted on a single graph and then illustrate the deformation to load
repetitions.
The rut depth of a number of loads repetitions is defined as the maximum vertical downwards
deformation in the wheel track. The upward deformation next to the wheel track defined as the
heaving. It occurs when material from the path of the wheel pushing outwards to the side of the
wheel, either through creep or through classical shear. This phenomenon however, is typical for
the HMA, and not for BSMs.
A typical example of HMA surface profile after trafficking presented in Figure J.5 below.
Figure J.5: Typical plot of the HMA surface of deformed profile
5

2. METHODOLOGY
2.1. MMLS3 Test Configuration
Some tests initially conducted with the MMLS3 for the investigation of bituminous stabilised
materials BSM’s with water exposure. This research included trafficking of nine (9) BSM-foam
and BSM-emulsion specimens placed side by side in the water bath, under saturated conditions
i.e. with the specimens immersed in water. The research showed that one of the major
challenges with wet trafficking of BSM’s is the premature failure of the mixes after water
exposure i.e. the test can require termination at less than 5000 wheel repetitions due to
disintegration of the specimens, compared with similar tests on HMA that endure for 10 to 20
times longer. It is a challenge therefore to develop a test protocol that provides sufficient testing
time i.e. 50 000 to 100 000 wheel repetitions, to develop a sensitivity to the mix’s performance.
The solutions to this challenge presented in this study as follows:
Modification of MMLS3 Set-up
Figure J.6 below present a schematic illustration of the MMLS3 set-up.
Figure J.6: Schematic illustration of the MMLS3
The MMLS3 device can apply 7200 wheel loads per hour and needs a single phase 200-240 Volt
AC supply at about 1.5kW. The tyre pressure of MMLS3 can be set up to 800 kPa, during the
initial tests the tyre pressure set at 650 kPa, which later adjusted to 420 kPa. This pressure is
equivalent to a light truck. The reason for a reduction in tyre pressure is to minimize damage
on BSMs and extend the test duration. The use of 420kPa also makes it possible to correlate
MMLS3 test results with MIST device test results. An air compressor used to calibrates the tyre
pressure. The wheel that used in this study is diamond tread tyres.
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An electric calibration unit used to set the axle wheel load, as shown in Figure J.7. The load of
the wheel in initial study set at 1.2 kN, that changed to 1.8kN for correlation with MIST device
test set-up. The selected 1.8kN is equivalent to a small truck, and by tensioning the springs, the
load of the wheel calibrated to the correct wheel load.
CALIBRATION UNIT
JUNCTION BOX
ELECTRONIC DISPLAY
CUT-OUT
MACHINE CROSS MEMBER
FLANGE A
SPRING SUPPORT
SPACER
NUT A
FLANGE B
NUT B
NUT C
PIN WITH CIRCLIP
10
GUIDE WHEEL
10mm GAP
RUBBER STOPPER
OUTLINE OF TYRE
Fig.3: Measuring and setting the wheel lo
Figure J.7: The calibration of the wheel load
The suspension system of the wheel designed so that the vertical displacement of the wheel,
within a range of less than 25mm, does not influence the pressure the wheel exerts on the
specimen.
The briquettes are placed in a steel beam, Figure J.15, with moulds tightened from the sides of
the beam to keep the specimens restrained in one position during testing. The testing set-up
however required modification. In the field, the vehicles do not drive directly on the BSM layer
i.e. there is always a surfacing above it, so some protection of the surface of the BSM briquettes
from ravelling is needed.
In reality, the BSM layer is used in the base or subbase, so some load distribution occurs in the
overlying layers, as illustrated in Figure J.8. Due to the reduction in the tyre pressures of the
MMLS3 for this testing, it would be preferable if the laboratory set-up of the MMLS3 did not
include a load spreading layer over the BSM because this would reduce the pore pressure
induction during wheel passages. Therefore, the protection or cover should not distribute the
stress over the briquettes, as shown in Figure J.9.
7

Surface
Base layer
Subbase layer
Figure J.8: The stress distribution in the different layers.
Vinite layer
BSM-Base layer
Figure J.9: MMLS3 load set-up no stress distribution on the protection layer.
The material that decided upon for the protection layer was vinite or reinforced rubber mat,
which is a very tough, flexible material. This layer, the green layer illustrated in Figure J.9 and
Figure J.10, should only protect the briquette from the abrasion of the wheel, with the intention
to minimize loosening of aggregates in the surface of the BSMs. A test was carried out with the
vinite protecting the specimens and after 100 000 load repetitions the cover and surface were
still in perfect condition. The grey path noted in Figure J.10 is result of the green colouring
wearing off through abrasions by the wheels.
Figure J.10: Plan view of the protective layer on the briquettes
8

2.2 BSMs for MMLS3 testing
The intention of this study is to validate materials that known to be resistant to moisture
damage and materials known to be susceptible to moisture damage. The Initial study included
validation of crushed Hornfels (G2) material. In the addition study, due to time constraints,
limited test were done on Hornfels (RAP) and Quartzites (G4) materials.
Due to the development of a compaction procedure for BSMs to produce triaxial sized
specimens, see Task 12, this procedure followed for the production of specimens for the MMLS3
tests. The triaxial specimens produced, have dimensions of 300mm high and 150mm in
diameter. By having specimen dimensions and an indication of the density of the material, the
amount of aggregates to mix one specimen is calculated. A mass of 12kg material needed to
make one specimen.
2.2.1 Mixing of the Materials
The initial study tested four different types of BSMs and additional study tested four different
types of materials as indicated in Table J.1. Three materials on the initial study tested after
accelerated laboratory curing. The fourth material selected from Hornfel-RAP with 1% cement
cured for more than 9 months at room temperature. The additional study also tested specimens
after accelerated laboratory curing, more tests are envisage on additional study however results
of only four tested materials were available during final report writing.
Table J.1: Mix type and testing Matrix
Binder type
A - Emulsion
B- Foamed
bitumen
Aggregates type
Initial test
Additional test
Crushed Hornfels (G2) Hornfels-RAP + 2% Quartzite + 2%
+2% residual binder residual binder
residual binder
Mix 1: 0% filler Mix 1: 0% filler Mix 4: 0% filler
Mix 2: 1% cement Mix 2: 1% cement
Mix 3: cured more than Mix 3: 1% lime
9 months
Mix 4: 0% filler
2.2.2 Curing
The curing of the specimens is an essential component on the development of strength within
the mixes before exposure to moisture. In order to carry out curing, the specimen is placed in
an oven just after compaction. Initially, the specimen is placed in the oven for 20 hours
unsealed at a temperature of 30ºC. Without sealing from the dry warm air, the moisture reduces
9

in the specimen, which strengthens the mix. The specimen then covered with a plastic bag and
sealed for two x 24 hours intervals so that no further moisture removed from the specimen at a
temperature of 40ºC. This accelerated curing procedure is equivalent to 7 to 14 days in the field,
(Malubila, 2005).
2.2.3 Cutting of specimens
Following curing and cooling to ambient temperature, the specimens are ready for cutting. The
cutting processes need attention and care, to minimise any damage to the specimen. The
cutting of BSMs with additional of active filler is easier than BSMs without active filler. The latter
mix is less cohesive and rather brittle, so spalling of the aggregate occurs if the wrong cutting
technique is applied. The cutting of the BSMs without active filler is made easier by reducing the
specimen temperatures in a fridge to below freezing. There are two types of blades that are
used for cutting of the specimen. The slotted blades are for cutting the specimen into slices of
90mm. The continuous blade is more for trimming and delicate cutting.
The dimensions of the specimen after compaction are 300mm tall with a diameter of 150mm.
Each specimen is cut into slices of 90mm high. However, due to difficulties in cutting 300mm
specimen, an alternative measures taken to compact two layers of 50mm and later trim the
specimen to size indicated in Figure J.11 and Figure J.12.
Figure J.11: The top view of the specimen before and plan for cutting
The next step is to remove the sides of the specimen, so it can fit in the MMLS3 set-up. The
diameter of the specimen is 150 mm and the sides of the specimen cut off to a size of 110mm,
as illustrated in Figure J.12.
10

Figure J.12: The side view of the briquette before and after cutting.
The cut briquettes placed in MMLS3 set-up and ready for test. Figure J.13 shows a photo of
specimens after cutting. However, Briquettes of G2 materials suffered serious spalling during
cutting.
Figure J.13: Briquettes after cutting (G2-Materials and Quartzites-G4)
Figure J.14: Proper cutting with minor damage on BSM-Emulsion
(Quartzite Aggregates with No filler)
Sample preparation i.e. mixing, compaction and cutting, plays a significant role in the
mechanical testing of the BSM-specimen. Proper handling of BSM specimens during production
11

gives a quality specimen, which in turn produce a reliable result. Figure J.14 is a photo of final
cut of BSM-emulsion of Quartzites with no active filler.
2.3 MMLS3 Testing
Two sets of similar mixes were prepared for the MMLS3 testing. One set tested in the wet
condition and another in dry condition. After MMLS testing, the ITS test is done to enable
determination of the tensile retained strength (TRS), i.e. wet over dry ITS.
The initial MMLS3 tests carried out on four different BSMs. Two BSM-emulsions and one BSMfoam
was tested after accelerated laboratory curing, and one BSM-emulsion tested after curing
in the laboratory at room temperature for more than 9 months. In addition, four more BSMemulsion
mixes tested as indicated in Table J.1 above. The steel beam set-up accommodates
nine briquettes of which seven specimens are monitored during trafficking; the other two are
placed at either ends of the traffic path as dummy specimens. The dummy specimens are made
of HMA, which does not fail under the dynamic effects of the wheel loads during the transition
onto the trafficked specimens. The layout of the briquettes and the profilometer guide indicated
in Figure J.15.
Dummy
07
06
Profilometer guide
05
04
03
02
01
Steel beam
Dummy
Figure J.15: The layout of the briquette and profilometer guide
The layout of the seven monitored specimens may include different combinations. Two different
combinations are appropriate in one test for statistical purposes. The combination may monitor
three briquettes of either BSM-emulsion and/or four of BSM-foam, made of different aggregates
type or with and without active filler.
The profile of the trafficked briquettes measured using a profilometer at exponential intervals of
trafficking. All the briquettes measured except the dummy specimens at the ends of the beam.
After every interval, i.e. a defined number of load repetitions, the MMLS3 is removed from the
set-up and the profile of the surface of the briquettes measured.
12

The set-up of the test before trafficking commences, is a time consuming procedure. After the
specimens fastened into the steel beam, water is filled to a level in the bath 2mm above the
specimen’s surface. The water depth is kept steady by a weir at the end of the bath. The water
is pumped out of the weir and repeats the cycle all the time to maintain water level.
The water temperature during testing maintained at 25ºC using a thermally adjustable water
pump. The number of load repetitions at which profile measurements are taken differs according
to the type of BSM. Generally, more measurements are made early on during the test i.e. at
shorter intervals, because the rutting profile has an exponential relationship with time. However,
as shown in the following table, the number of load repetitions at which the MMLS3 test is
terminated, can vary significantly:
Table J.2: The number of load repetitions per measurement cycle wet condition
BSM Type
Loads per measurement cycle [No]
Initial (preliminary ) test
2% emulsion +1% cement
DNM 50 000 75 000 100 000
(long cured)
2% emulsion + 0% cement (G2) 0 500 900 Failure
2% emulsion + 1% cement (G2) 0 250 Failure -
2% foam + 0% cement (G2) 0 250 Failure -
Additional test
2% emulsion +1% cement (H-RAP) 0 45000 Failure
2% emulsion +1% lime (H-RAP) 0 45000 Failure
2% emulsion +0% cement (H-RAP) 0 2500 Failure
2% emulsion +0% cement (Q-G4) 0 2500 Failure
Failure = means ravelling –depth more than 12mm
After identification of the number of wet-trafficked axles to failure for a specific mix, the second
set of briquettes tested under dry condition to the same number of load application applied for
wet condition. Thereafter two sets specimens (dry and wet) could be tested in the ITS mode to
determine the tensile strength retained TSR i.e. wet over dry.
2.4 ITS Testing
Subsequent to trafficking, Indirect Tensile Strength (ITS) tests carried out on the specimens
removed from the MMLS3 test set-up. These tests results were then compared with ITS tests
performed on specimens not subjected to wet trafficking. In this way, a TSR result assessed for
the different BSM-mixes.
The Indirect Tensile Strength test performed using MTS equipment. The loading rate applied
during ITS test is 50.8mm/min. The Indirect Tensile Strength and tensile strength ratio of the
BSMs computed as follows, Equation 1 and 2:
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Indirect Tensile strength (ITS) =
2000 xP
π xDxt
max
Equation 1
ITS
wet
Tensile Strength Ratio (TSR) = x100
ITS
dry
Equation 2
Where:
P max
D
t
= maximum applied load, [N]
= specimen diameter [mm]
= average specimen height after MMLS test [mm]
ITS wet = Indirect Tensile Strength at wet condition [kPa]
ITS dry
= Indirect Tensile Strength at dry condition [kPa]
As shown in Figure J.16, the Indirect Tensile Strength test performed on MMLS specimen at
room temperature (25ºC).
Figure J.16: ITS test set-up on specimen after MMLS3 testing
14

3. TEST RESULTS
The use of vinite or reinforced rubber mat minimises the direct abrasion of wheel on the
specimens. However, during testing the vinite layer seen not prevent ravelling once the
materials start disintegrating. The ingress of water into specimen under trafficking destroys
cohesion of the mix resulting in loss of aggregate. Heaving along the edges of the wheel path is
not a primary failure. Nevertheless, aggregate loss does prevail in the wheel path resulting into
ravelling deformation. The ravelling depth is recorded on profilometer measurement on each
BSMs. The results for Initial test and additional tests are presented in the following subsections:
3.1 Initial tests on BSMs
Table 3: Ravelling-depth after MMLS3 trafficking on wet BSMs long cured specimen
BSM-Mix type
specimen
(new labelling
style)
Preliminary
specimen
labelling style
No of load repetitions
75 000 100 000
Ravelling-depth [mm]
H+1C-E01 A1* 0.074 0.009
H+1C-E01 A2 0.073 0.003
H+1C-E01 A3 0.039 0.119
H+1C-E01 A4 0.002 0.079
H+1C-E01 A5 0.006 0.034
H+1C-E01 A6 0.031 0.068
H+1C-E01 A7 0.088 0.116
Average 0.045 0.061
Std 0.034 0.048
Cov 0.78 0.78
* A’s are preliminary labelling which changed to new format.
15

Table 4: Ravelling-depth after MMLS3 trafficking on wet BSM-emulsion with 0% filler
BSM-Mix type
specimen
(new labelling
style)
Preliminary
specimen
labelling style
No of load repetitions
500 900
Ravelling-depth [mm]
G2+0C-E01 B1* 1.14 4.61
G2+0C-E02 B2 1.91 2.03
G2+0C-E03 B3 2.66 2.33
G2+0C-E04 B4 0.48 2.01
G2+0C-E05 B5 1.66 0.21
G2+0C-E06 B6 1.36 0.21
G2+0C-E07 B7 1.07 0.59
Average 1.47 1.71
Std 0.69 1.56
Cov 0.47 0.91
* B’s are preliminary labelling which changed to new format.
Table 5: Ravelling-depth after MMLS3 trafficking on wet BSM-emulsion with 1% cement
No of load repetitions
250 500
BSM-Mix type
specimen
(new labelling
style)
Preliminary
specimen
labelling style
Ravelling-depth [mm]
G2+1C-E01 C1* 3.79 Failure
G2+1C-E02 C2 3.25 -
G2+1C-E03 C3 1.65 -
Average 2.90
Std 1.11
Cov 0.38
* C’s are preliminary labelling which changed to new format.
Table 6: Ravelling-depth after MMLS3 trafficking on wet BSM-foam with 0% filler
No of load repetitions
250 500
BSM-Mix type
specimen
(new labelling
style)
Preliminary
specimen
labelling style
Ravelling-depth [mm]
G2+0C-F01 D1* 3.92 Failure
G2+0C-F02 D2 2.65 -
G2+0C-F03 D3 3.59 -
G2+0C-F04 D4 4.36 -
Average 3.63
Std 0.72
Cov 0.02
* C’s are preliminary labelling which changed to new format.
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Table J.7: ITS results after wet and dry MMLS3 trafficking
Wet trafficking
type ITS
specimen [kPa]
BSM-Mix
Type
Dry (trafficking)
ITS
Type
[kPa] Specimen
H+1C-E01 98.8 130.8 H+1C-E04
H+1C-E02 76.5 130.8 H+1C-E05
BSM-Emulsion BC
H+1C-E03 113.9 128.5 H+1C-E06
2% +1% cement
Average 96.4
(long cured)
130.0 Average
Std 18.8 1.33 Std
Cov 0.19
0.01 Cov
G2+0C-E01 86.6 107.7 G2+0C-E04
G2+0C-E02 103.5 109.7 G2+0C-E05
BSM-Emulsion BC
G2+0C-E03 103.1 115.8 G2+0C-E06
2% +0% cement
Average 97.7 111.1 Average
Accelerated cure)
Std 9.6 4.2 Std
Cov 0.10
0.04 Cov
Table J.8: ITS results after wet and dry MMLS3 trafficking
Wet trafficking
type ITS
specimen [kPa]
BSM-Mix
Type
Dry (trafficking)
ITS Type
[kPa] Specimen
G2+1C-E01 62.2 92.3 G2+1C-E04
G2+1C-E02 74.4 85.8 G2+1C-E05
BSM-Emulsion BC
G2+1C-E03 BROCK 82.8 G2+1C-E06
2% +1% cement
Average
Accelerated cure)
Average
Std
Std
Cov
Cov
G2+0C-F01 54.4 114 G2+0C-F01
G2+0C-F02 BROCK 73.2 G2+0C-F02
BSM-Foam BC
G2+0C-F03 BROCK 75.5 G2+0C-F03
2% +0% cement
Average
Accelerated cure)
Average
Std
Std
Cov
Cov
17

3.2 Additional tests on BSMs
Table 9: Ravelling-depth after MMLS3 trafficking on wet BSM-emulsion with 0%
filler
BSM-Mix type
No of load repetitions
specimen 500 1500 2500
Rut-depth [mm]
H+0C-E01 1.98 6.75 14.37
H+0C-E06 1.02 2.97 15.12
H+0C-E07 1.14 8.55 14.14
Average 1.38 6.09 14.54
Std 0.52 2.85 0.51
Cov 0.38 0.47 0.04
Q+0C-E08 0.36 0.30 12.77
Q+0C-E06 0.78 0.57 12.16
Q+0C-E05 1.30 0.60 12.20
Q+0C-E04 0.64 1.18 12.39
Average 0.77 0.66 12.38
Std 0.39 0.37 0.28
Cov 0.51 0.56 0.02
Table 10: Ravelling-depth after MMLS3 trafficking on dry BSM-Emulsion with 0%
filler
BSM-Mix type
No of load repetitions
specimen
1500 2500*
Rut-depth [mm]
H+0C-E02 No deformation 1.20
H+0C-E03 0.99
H+0C-E04 0.81
H+0C-E08 0.85
Average 0.96
Std 0.18
Cov 0.19
Q+0C-E07 0.78
Q+0C-E03 0.52
Q+0C-E01 0.76
Average 0.69
Std 0.15
Cov 0.21
* Test stopped at 2500 for comparison with wet test on the retained tensile strength
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Table 11: Ravelling-depth after MMLS3 trafficking on wet BSM-emulsion with 1%
cement
BSM-Mix
No of load repetitions
type
specimen 200 3000 7000 15000 25000 40000 45000
Ravelling-depth [mm]
H+1C-E02 0.53 0.69 0.19 -0.14* -0.23 0.12 0.1
H+1C-E03* - - - - - - -
H+1C-E06 0.24 0.16 0.00 -0.28 -0.43 -0.24 -0.13
Average 0.39 0.42 0.10 -0.21 -0.33 -0.06 -0.01
Std 0.21 0.37 0.13 -0.09 -0.14 -0.08 -0.02
H+1L-E08 0.25 0.05 0.07 -0.18 0.77 3.28 7.07
H+1L-E05 0.40 0.64 0.61 0.88 2.55 3.39 8.45
H+1L-E03 0.63 0.66 0.62 0.68 0.58 6.28 12.87
H+1L-E02 0.58 0.71 0.65 0.74 0.68 2.78 13.86
Average 0.47 0.51 0.49 0.53 1.14 3.98 10.56
Std 0.17 0.31 0.28 0.48 0.94 1.59 3.31
Cov 0.37 0.60 0.57 0.91 0.82 0.40 0.31
* Data not recorded during profilometer measurement
* The (-ve) value occurred due averaging the profilometer point reading
Table 12: Ravelling-depth after MMLS3 trafficking on dry BSM-emulsion
with 1% cement
BSM-Mix
No of load application
Type specimen
1000 1700 45000
Ravelling-depth [mm]
H+1C-E01 0.59 0.66 0.41
H+1C-E04 0.46 0.57 0.41
H+1C-E05 0.39 0.45 0.32
Average 0.48 0.54 0.4
Std 0.10 0.11 0.05
Cov 0.21 0.19 0.14
H+IL-E09 0,59 0.76 0.91
H+1L-E07 0.43 0.53 0.33
H+1L-E06 0.56 0.43 0.47
H+IL-E01 0.56 0.71 0.72
Average 0.52 0.61 0.61
Std 0.08 0.15 0.26
Cov 0.15 0.25 0.23
19

Table 13: ITS results after wet and dry MMLS3 trafficking
Wet trafficking
Type ITS
specimen [kPa]
BSM-Mix
Type
Dry (trafficking)
ITS Type
[kPa] Specimen
H+0C-E01 12.7 60.1 H+0C-E02
H+0C-E06 24.7 79.1 H+0C-E03
H+0C-E07 13.1 BSM-Emulsion BC 76.9 H+0C-E04
Average 16.8 2% +1% cement 95.5 H+0C-E08
Std 6.8 Accelerated cure) 77.9 Average
Cov 0.04 14.5 Std
0.19 Cov
Q+0C-E04 125.2 368.1 Q+0C-E04
Q+0C-E05 157.9 415.2 Q+0C-E05
Q+0C-E036 95.1 BSM-Emulsion BC 237.5 Q+0C-E06
Q+0C-E036 285.2 2% +0% cement 340.3 Average
Average 165.9 Accelerated cure) 92.1 Std
Std 83.6 0.27 Cov
Cov 0.50
Table 14: ITS results after wet and dry MMLS3 trafficking
Wet trafficking
type ITS
specimen [kPa]
BSM-Mix
Type
Dry (trafficking)
ITS Type
[kPa] Specimen
H+1C-E02 113.9 154.3 H+1C-E01
H+1C-E05 198.2 241.9 H+1C-E04
BSM-Emulsion BC
H+1C-E06 74.5 178.3 H+1C-E05
2% +1% cement
Average 128.9
Accelerated cure)
191.5 Average
Std 63.2 45.3 Std
Cov 0.49
0.24 Cov
H+1L-E02 57.1 132.0 H+1L-E01
H+1L-E03 51.6 108.5 H+1L-E06
H+1L-E05 41.6 BSM-Emulsion BC 103.1 H+1L-E07
Average 50.1 2% +0% cement 86.2 H+1L-E09
Std 7.9 Accelerated cure) 107.5 Average
Cov 0.16 18.9 Std
0.18 Cov
20

Table 15: Tensile Strength Retained after wet and Dry MMLS3 trafficking
BSM-Mix
Type
Average ITS Value
Wet ITS Dry ITS
TSR
[kPa] [kPa] [%]
H+1C-E (long cure) 96.4 130 74
G2+0C-E (accelerate cure) 97.7 111.1 88
G2+1C-E (accelerate cure) 96.4 120.6 80
G2+0C-F (accelerate cure) 54.4 87.6 62
H+0C-E (accelerate cure) 16.8 77.9 22
Q+0C-E (accelerate cure) 165.9 340.3 49
H+1C-E (accelerate cure) 128.9 191.5 67
H+1L-E (accelerated cure) 50.1 107.5 47
21

4. ANALYSIS AND DISCUSSION OF RESULTS
The objective of this section is to provide an overview on the findings of MMLS3 testing and
subsequent ITS testing on wet and dry trafficked BSMs. The results obtained in APT device
(MMLS3) and ITS used to establish possible correlation or trend between MMLS3 and MIST
device testing system. The relationships between these devices also provide an insight of
moisture related damage on different BSMs. Through the results, screening of the different
BSMs in terms of moisture susceptibility defined.
In an attempt to observe the performance of proposed MMLS3 test set-up for the BSMs, the
initial study tests conducted with different test variables. These variables include 680kPa tyre
pressure, 1.2kN wheel load, and 7200wheel per hour, with installation of vinite layer at the top
of briquettes. The additional tests however, were carried out at new testing variables to
correlate with the variables predetermined for the MIST device. The new variables were 420kPa,
1.8kN, and speed of 7200wheel per hour. The combination of new variables allowed acceptable
number load application of MMLS3 trafficking and correlation with MIST device testing system
on BSMs.
The study of different factors related to moisture damage on the BSMs was investigated. These
factors described in subsequent subsections.
4.1 Load application on BSMs
The impact of moisture on pavement performance differs depending on the type of pavement,
loading condition, temperature, and degree of saturation. A BSM in pavement layer is used as
base or subbase, in order to enable load distribution in the structure. The interaction of the
surface traffic and pore pressure developed in BSMs due to ingress of water is complex. In this
study, the MMLS3 test variables were scaled down to correlate with MIST device. Due to
reduction of tyre pressure and wheel load, the installation of vinite or rubber mat layer used to
ensure the pore pressure effect not reduced in the BSMs during trafficking. The installation of
vinite or rubber mat does not simulate field conditions, but merely minimises direct abrasion of
the wheels on the BSM-layer and help screening BSMs in terms of moisture related damage.
As outlined above, different BMSs were investigated during MMLS3 and MIST testing in the
laboratory. Figure J.17 present a comparison of BSMs performance on load application to failure
in wet condition, at 25 o C, 420kPa, 1.8kN, and speed of 7200wheel per hour.
22

The comparison of BSMs on Figure J.17 show that BSM-emulsion with long curing condition
performed extremely good with 100 000 loads application, compared to other BSMs tested after
standard accelerated curing.
Cumulative no. of load application
BSM-Mix
100000
10000
1000
100
10
1
0.1
0.01
H+1C-
E
(long)
G2+0C-
E07
G2+1C-
E01
G2+0C-
F04
H+1C-
E06
H+1L-
E02
Q+0C-
E08
H+0C-
E07
No of load application 100000 900 250 250 40000 40000 2500 2500
Ravelling-depth 0.06 1.71 2.9 3.6 0.01 3.98 12.38 14.54
Figure J.17: Cumulative number of load applications to failure of BSMs in wet
condition at 25 o C, 420kPa, 1.8kNa and speed of 7200wheel per hour.
Further comparison in Figure J.17, the BSMs with crushed Hortnfels (G2) materials carry less
load applications than BSMs with Hornfels-RAP and Quartzites materials. The impact of addition
of active filler is obvious. BSMs with no addition of active filler fail at a lower number of load
applications (i.e. 250 to 2500) compared to BSMs with the addition of active filler, which fails at
45000.
However, looking at the values of load applications on crushed Hornfels (G2) materials, they
seem unexpectedly low. This might have occurred due to initial set-up of higher tyre pressure,
as well as the spalling of specimen indicated in Figure J.14. It is counter-intuitive that the
crushed Hornfels (G2) material with additional of cement fails at less load applications i.e. 250
than the crushed Hornfels (G2) material with no cement i.e. at 900 load applications. As stated
previously, sample preparation has significant impact on the mechanical performance of the
BSMs.
In conclusion, the comparison of BSMs indicates that long cured mixes have significant
resistance to moisture damage compared to accelerated cured mixes. BSM-foam or BSMemulsion
mixes with crushed Hornfels (G2) material seem to be moisture susceptible compared
to BSM-emulsion with Hornfel-RAP or Quartzites. Addition of active filler has proven to add
resistance of the BSMs to moisture susceptibility.
23

The disintegration of BSMs due to wet trafficking might occur due to quality of aggregates,
cohesion and adhesion of aggregates-binder interface, void on the mixes, saturation level,
temperature etc. The following subsection discusses findings on disintegration and ravelling
results from MMLS3 testing.
4.2 Disintegration and ravelling of BSMs
Monitoring of the disintegration and ravelling of progressing MMLS3 test under wet trafficking
consists of two types. Firstly, the surface disintegration, which monitored visually on spalled
aggregates at intermittent times during trafficking. The spalling of aggregates can cause
punchering of the wheel as well as vinite layer during trafficking. Secondly, cohesion loss or
stiffness deterioration during wet trafficking is measured as cumulative ravelling using
profilometer. The profilometer is placed transversely in seven (7) different positions along the
beam i.e. on each specimen being tested. Data on cumulative ravelling is recorded and present
in Tables shown in Section 3.1, and 3.2.
The disintegration during MMLS3 test shows that, wet trafficking creates more damage in terms
of cohesion loss or stiffness reduction than dry trafficking. The comparison made at the same
number of load applications and testing temperature. No sign of significant initial densification
occurred on BSMs. However, stiffness of the trafficked materials decreases as number of load
application increases. This suggests that cohesion loss has occurred under traffic and the
damage is aggravated by pore pressures in the presence of water.
As an example of the ravelling results, Figure J.18 illustrates transverse ravelling profile
measured on wet trafficking. Forty five thousand (45000) cumulative wheel loads were applied
during this test.
-2
Ravelling-depth [mm]
-0.5 0 50 100 150 200 250
1
2.5
4
5.5
7
8.5
0
200
3000
7000
15000
25000
40000
45000
Profilometer position 4
Figure J.18: Transverse ravelling measured during wet MMLS3 trafficking
24

From Figure J.19 it can be seen that predominant mode of distress is loss of material. The
materials move along and sides of the wheel path as loss of cohesion or stiffness reduction
progresses.
Less moisture susceptible mix
Moisture susceptible mix
Loss of
material
along and
side the
wheel path
Figure J.19: Loss of material of different BSMs on wet MMLS3
trafficking after 45000 load application
Figure J.20 shows the typical failure mechanism of BSMs under wet trafficking. The comparison
made between BSM-emulsion with Hornfels-RAP and addition of active filler at fully saturation.
The BSMs with Hornfels-RAP with addition of 1% lime is relative moisture susceptible compared
to BSM-emulsion with Hornfels-RAP with addition of 1% cement. Looking at the testing
procedures, the conclusion can be drawn that the established protocol can identify and rank
BSMs in terms of moisture related damage. It is clear from the test results the use of the APT
Device (MMLS3) has potential for identification of the varying degrees of distress that BSMs
suffer under wet trafficking. From this result, a reliable correlation of the MMLS3 Device and
MIST device testing system is achievable.
A further observation on the disintegration and ravelling results, prove that cohesion loss and
stiffness reduction develop progressively. Figure J.20 shows ravelling-depth development of
BSM-emulsion of Hornfels-RAP and BSM-emulsion of Quartzites without addition of active filler.
The insight on failure mechanism of these mixes is that severe reduction of cohesion or stiffness
occurred after 1500 load application. Thereafter an exponential increase in loss of materials
occurred. However, some briquettes that spalled during cutting show an early failure, indicating
that smoothness of the test surface can influence results.
25

H+0C-E01 H+0C-E06 H+0C-E07 Q+0C-E08
Q+0C-E06 Q+0C-E05 Q+0C-E04 AVERAGE
Ravelling –depth [mm]
16
14
12
10
8
6
4
2
0
-2
0 500 1000 1500 2000 2500 3000
Cumulative no. of load application
Figure J.20: Ravelling development of the BSM-emulsion mixes without active filler
In contrast, BSM-emulsion with Hornfels-RAP and the addition of active filler provide a different
insight into mix behaviour see Figure J.21. The BSM-emulsion of Hornfels-RAP with addition of
1% cement proves to be moisture resistant under wet trafficking. This mix shows little cohesion
loss or stiffness reduction after 45000 load applications. While the BSM-emulsion of Hornfels-
RAP with addition of 1% lime shows relative less resistance to moisture damage. The latter mix
suffered severe reduction in cohesion and stiffness after 40000 load applications.
H+1C-E02 H+1C-E06 AVERAGE H+1L-E08
H+1L-E05 H+1L-E03 H+1L-E02 AVERAGE
16
14
Ravelling –depth [mm]
12
10
8
6
4
2
0
0
-2
10000 20000 30000 40000 50000
Cumulative no. of load application
Figure J.21: Ravelling development of the BSM-emulsion mixes with active filler
26

4.3 Saturation Level
The moisture ingress (saturation level) in the BSMs depends on in particle interlock, particle
type, binder content, and additions of active filler. The mixes with high void contents shows
higher erosion due to high void pore pressure developed during wet trafficking. Figure 20 and
21 above exhibit that behaviour. Further observations on the results Figure 20 and 21 are that
the BSM-emulsion with Hornfels-RAP plus 1% lime proves to be relative resistant to moisture
damage up to a certain degree of saturation e.g. 80%. Thereafter severe cohesion loss and
reduction of stiffness occurs resulted to exponential disintegration. Similar behaviour of BSMs
with other aggregates plus 1% lime occurred on correlation test with MIST device testing
system. MIST test results presented in separate report included in Task 9.
4.4 Testing temperature
The testing temperature on this study was 25 o C, however field temperature in BSMs can vary
significantly. The effect of wet heated testing might result in a significant damaging effect in
terms of cohesion loss and stiffness reduction. However, moisture ingress and related damage in
South Africa will take place during rainfall period, where the air temperature does not exceed
30 o C. Therefore, as BSMs used in base or subbase layer temperature will not exceed 25 0 C.
During MMLS3 wet trafficking, the test temperature was controlled at 25 o C using thermocouples
attached to the briquette at Position 3 and 6 of the briquette layout. The thermocouple reading
was monitored intermittently during trafficking period.
4.5 ITS Testing
After the MMLS3 tests, further conclusive evidence of the materials distress due wet trafficking
could be observed upon removal of the trafficked briquettes and testing. The removal of
briquettes included precaution to avoid further damage. Thereafter, ITS test was carried out to
investigate the extent of distress on the BMSs due to wet trafficking performed. The
quantification of the reduction of tensile strength was measured from the wet (trafficked) and
dry (trafficked) briquettes. The Indirect Tensile Tests (ITS) was performed at the respective
number of briquette recovered from MMLS3 test. At least three (3) specimens from every type
of mix were tested. All ITS tests were performed at 25 0 C temperature. The ITS tests were done
at controlled displacement with applied rate of 50.8mm/min. The results of the ITS tests are
summarised in Table J.7, Table J.8 and Table 13Table 14.
Tensile Strength Retained (TSR) after wet and dry MMLS3 trafficking can be calculated as a Ratio
of average wet ITS over average dry ITS. The results of TSR presented in Table 15 above.
27

Figure J.22 illustrates the comparison of the strength reduction of BSMs from dry trafficking to
wet trafficking conditions. The wet trafficking ITS shows a decrease in strength from dry
trafficking ITS. However the comparison of the ITS values shows no significant difference for
most of the BSMs tested, with some exceptions i.e. BSM-emulsion with Quartzites. This indicates
that ITS test is not particularly sensitive to moisture effects.
From previous analysis, see Section 4.1, the resistance to disintegration and ravelling by a long
cured BSM-emulsion, indicated high moisture resistance. However, looking at the ITS values, the
difference between highly moisture resistant to highly moisture susceptible BSMs is insignificant.
This confirm the weakness of the ITS test, as reported previously by Hodgkinson, (2004). The
lack of reliability and repeatability of the ITS test for use in ranking BSMs in terms of moisture
susceptibility, should preclude its use for important applications of BSMs.
ITS [kPa]
400
350
300
250
200
150
100
50
0
H+1C-E01 (long cured
G2+0C-E02
G2+1C-E01
G2+0C-F01
H+0C-E01
BSM-Mixes
Q+0C-E04
H+1C-E02
H+1L-E02
Wet Trafficked ITS
Dry Trafficked ITS
Figure J.22: Comparison of ITS results after wet and dry MMLS3
trafficking on different BSMs
Further, comparison of the ITS values shows an increase in the moisture-sensitivity of the BSMs
from initial study to additional study. However, it should be noted that in the initial study, wet
trafficking terminated at 250 and 900 load applications after ravelling depth of 2mm to 4mm,
while in the additional study, wet trafficking terminated at a 2500 and 45000 load application
after ravelling-depth of 4mm to 12-14mm.
Ravelling-depth of 4mm under the MMLS3 appears to be critical, see Figure J.20 and Figure
J.21. At 4mm of ravelling BSMs experiences severe cohesion loss of stiffness reduction.
Thereafter exponential disintegration occurs. It is appropriate to extend testing beyond 4mm of
ravelling during moisture susceptibility testing with the MMLS3 trafficking.
28

Ravelling-Depth [mm
16
14
12
10
8
6
4
2
0
H+1C-E (long)
G2+0C-E07
G2+1C-E01
G2+0C-F04
Ravelling-depth
H+1C-E06
BSM - Mixes
H+1L-E02
Q+0C-E08
H+0C-E07
Figure 23: Illustration of the Ravelling-Depth performance of
BMS-Mixes after wet MMLS3 trafficking
It is clear from the analysis presented in Figure 24 that early termination of trafficking might
result into less sensitivity of the strength ratio. Moreover, late termination results to high
sensitivity of strength ratio, hence causing irrational ranking of the BSMs. Figure 24 shows
different shifts in strength reduction of BSMs of both premature and extended termination of
MMLS3 trafficking.
Wet Trafficked ITS
Dry Trafficked ITS
400
ITS [kPa]
350
300
250
200
150
100
50
0
H+1C-E01 (long cured)
G2+0C-E02
G2+1C-E01
G2+0C-F01
H+0C-E01
BSM-Mixes
Q+0C-E04
H+1C-E02
H+1L-E02
Figure24: The shift indication between wet ITS and dry ITS after MMLS3
trafficking
The selection criteria of BSM-mixes, according to South African Guideline TG2, shows that TSR
values of greater that 75% is ranking GOOD resistance to moisture damage; while greater than
60% is ranking MEDIUM resistant to moisture damage and less than 50% is ranking POOR
resistant to moisture damage.
29

Taking into account the stated TSR ranking criteria, and comparing these results with ravelling
depths from MMLS3 tests as well as previous triaxial analysis which provided Retained Cohesion
ratios, provides the comparisons in Figure 25. This highlights the empirical nature of the TSR in
measuring moisture related resistance of BSMs, as it is inconsistent with the other results.
Reasonable comparison is obtained from MMLS3 tests and triaxial tests in terms of moisture
sensitivity of BSMs. However, only limited results are available at present although more
research is in progress.
Tensile Strength Retained [TSR] Ravelling-Depth [RvD] Retained Cohesion [RC]
Retained Ratio [%]
90
80
70
60
50
40
30
20
10
0
H+1C- G2+0C- G2+1C- G2+0C-
E01
(long
cured)
E02 E01 F01
H+0C-
E01
BSM - Mixes
Q+0C-
E04
H+1C-
E02
H+1L-
E02
Figure 25: The correlation between TSR, RC and RvD on moisture susceptibility of
BSM-mixes
The clearer perspective of the TSR results relative to other retained ratios is presented in Figure
26.
Tensile Strenght Retained (TSR) Retained Cohesion (RC) Ravelling-depth (RvD
Retained Ratio [%]
100
90
80
70
60
50
40
30
20
10
0
H+1C-
E01
(long
cured)
G2+0C-
E02
G2+1C-
E01
G2+0C-
F01
H+0C-
E01
BSM - Mixes
Q+0C-
E04
H+1C-
E02
H+1L-
E02
16
14
12
10
8
6
4
2
0
Revelling-Depth[mm]
Figure 26: The shift indication between TRS, RvD and RC on moisture susceptibility
of BSM-mixes
30

From the study conducted in MIST device (Task 9), it suggests that ranking of BSM-Mixes interms
of moisture related damage should consider limiting the Retained Cohesion (RC). The
Retained cohesion limits provide reliable classification of BSMs. Retained Cohesion further
indicate the factors contributing to mechanism of failure of BSMs, such factors are cohesion loss
and stiffness reduction. The proposed classification limits in terms of moisture susceptibility are
present in Table 16.
Table I.6: Recommended MIST pulsing cycle for the moisture damage
MIST
Pulsing cycle
[no.]
MIST
pulsing time
[min]
Equivalent residual
cohesion percentage
[%]
Possible equivalent
design material
100 3.2
≥ 75 BSM 1
≥ 60 BSM 2
≥ 50 BSM 3
31

4. CONCLUSIONS AND RECOMMENDATIONS
The investigation on wet trafficking and fundamental characteristics of BSMs associated with
moisture damage studied through APT (MMLS3) device approach. Based on the data of the
study, the following conclusions and recommendations are drawn:
The approach employed in wet trafficking in this study successful accomplished the objectives
to,
- investigate test procedure, which is applicable for BSMs on moisture exposure using APT
device (MMLS3).
- validate the behaviour of selected BSMs on moisture susceptibility
- Correlate the validated behaviour of BSMs on MMLS3 to the MIST device testing system.
- Make appropriate recommendations regarding the use of the APT device on screening
BSMs based on moisture related damage for mix design
4.1 Load application
- The used of APT Device (MMLS3) has shown potential in identification of BSMs distress
under wet trafficking. It can therefore suitably be adapted for testing Bituminous
Stabilised Materials (BSMs).
- The use of vinite or reinforced rubber mat proves to minimise the direct abrasion of
wheel to the specimen. However, the vinite layer seen not be effective once severe
cohesion loss of BSMs occurred.
- The new variables applied on MMLS3 i.e. 420kPa tyre pressure, 1.8kN wheel load, and
speed of 7200wheel per hour, seemed to provide acceptable level of screening the BSMs
in term of moisture susceptibility.
- The new variables applied on MMLS3 also found to validate the results obtained with
MIST testing device.
- The influence on curing of BSMs on wet performance is significant. Long term cured
BSMs withstanding significant number of load application (100 000 wet axles) with small
ravelling. Whilst the equivalent BSMs with an accelerated laboratory cure withstand less
wet axles before severe disintegrate.
4.2 Disintegration and ravelling
- The disintegration of BSMs during MMLS3 test show that, wet trafficking has more
damage in term of cohesion loss or stiffness reduction compared to dry trafficking. This
suggests that cohesion loss occurred under traffic and the damage aggravated by pore
pressure in the presence of water.
32

- No sign of significant initial densification occurred on BSMs. However, cohesion loss or
stiffness reduction of the trafficked materials increases as number of load application
increases.
- The level of disintegration and ravelling on BSMs under wet trafficking, shows that
cohesion loss and stiffness reduction develop progressively. The failure mechanism of
BSMs is that severe reduction of cohesion or stiffness occurs, before exponential loss of
materials occurred.
- Sample preparation need care to ensure smoothness of the test surface. Briquettes that
spalled during cutting show an early disintegration on wet trafficking.
- The performance of BMSs exposed to moisture during trafficking shows significant
differences. The long cured BSM-emulsion proves to be moisture resistant, than BSMs
with laboratory accelerated curing.
- The influence of the addition of the active filler in BSMs is vital for the improvement in
moisture susceptibility. The results indicate that BSMs with addition of 1% cement is
more moisture resistant compared to BSMs with addition of Lime or no active filler.
However interesting results on the addition of 1% lime is that, the BSMs endure moisture
resistant to a certain saturation level up to 80%, thereafter exponential disintegration
occurred.
4.3 Testing Temperature
- The MMLS3 wet trafficking and ITS tests were conducted at controlled 25 o C. It is obvious
that the field temperature on BSMs varies significantly, however in South Africa moisture
related damage occurred during rainfall period. During that period air temperature, do
not exceed 30 o C. Therefore, BSM-layer being a base or subbase its temperature will not
excess 25 0 C.
4.4 ITS test results
- The comparison of the ITS Values in all BSMs show no significant difference, with
exception of BSM-emulsion made of quartzites and no active filler. This indicates that ITS
test is not particular sensitive to moisture effect.
- From the analysis, long term cured BSM-Mixes proved to be highly moisture resistant
compared to laboratory accelerated cured BSM-mixes. However the ITS results show
insignificant difference between these BSMs. The lack of reliability and repeatability of
the ITS test for use in ranking BSMs in terms of moisture susceptibility, should preclude
its use for important applications of BSMs.
- Ravelling-depth of 4mm under the MMLS3 wet trafficking appears to be critical. It is
appropriate to extend testing beyond 4mm for better screening the BSMs.
33

- The relationship between Tensile Strength Retained (TSR), Ravelling-depth (RvD) and
Retained Cohesion (RC) highlights the empirical nature of the TSR in measuring moisture
related resistance of BSMs, as it is inconsistent with the other results. Reasonable
comparison is obtained from MMLS3 tests and triaxial tests in terms of moisture
sensitivity of BSMs.
4.5 Recommendations
- The used of APT Device (MMLS3) has shown potential in identification of BSM-Mixes
distress under wet trafficking. It can therefore recommend being adapted for testing
Bituminous Stabilised Materials (BSMs).
- The use of vinite or reinforced rubber mat in the wet MMLS3 trafficking, proves to
minimise the direct abrasion of wheel to the specimen. The flexibility of the vinite layer
does not distribute stress to the briquettes, while maintaining the pore pressure induction
during wheel trafficking. Therefore, recommended for use in MMLS3 testing, for possible
ranking of the BSMs in moisture susceptibility.
- The new testing variables applied during MMLS3 testing i.e. 420kPa, 1.8kN and
7200wheel per hour found to validate results obtained with MIST device testing system.
Therefore, recommended for use in both APT device (MMLS3) and MIST device.
- The influence of additional of active filler in the BSM-Mixes is vital for the improvement in
moisture susceptibility. Therefore, addition of 1% cement recommended in BSMs,
however depending on the severity of saturation level, the use of 1% lime would provide
sustainable moisture resistance similar to addition of cement.
- Ravelling-depth of 4mm under the MMLS3 wet trafficking appears to be critical. It is
recommended to extend testing beyond 4mm for better screening the BSMs.
- The lack of reliability and repeatability of the ITS test for use in ranking BSMs in terms of
moisture susceptibility, should preclude its use for important applications of BSMs.
34

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foamed asphalt mixtures. Proceedings of the 29 th Annual Canadian Technical Asphalt Association
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JENKINS J.K., 2000. Mix design considerations for cold and half-warm bituminous mixes with
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