Transcript of Sats test and surface energy
- 1. Presented By: KHALID MEHMOOD 2K13-FT-MSC-TRAN-06 TANVEER UL
HAQ2K13-PT-MSC-TRAN-11
- 2. BACKGROUND: Moisture damage in an asphalt mixture can
bedefined as the loss of strength, stiffness and durability Due to
the presence of moisture leading to: Adhesive failure at the
binderaggregateinterface Cohesive failure within the binder or
binder filler mastic OR pavement.
- 3. SATS TEST: The saturation ageing tensile stiffness(SATS)
Test is a combined ageing/moisture sensitivity laboratory test
consists of initial saturation prior to placing compacted asphalt
core samples in a high-temperature and high pressure environment in
the presence of moisture for an extended period of time
- 4. CONTINUE The stiffness modulus measured afterthe test
divided by the stiffness modulus measured before the test (retained
stiffness modulus) and the specimen saturation after the test
(retained saturation), are used as an indication of the sensitivity
of the compacted mixture to combined ageing and moisture
effects.
- 5. DEVELOPMENT OF SATS TEST: In real condition, moisture damage
inasphalt Pavement is need to have the test methods which
incorporate several sources of damage in conditioning the tested
sample to demonstrate the real condition. An effort towards this
approach was conducted by Collop, who developed of a combined
ageing and moisture sensitivity laboratory test for asphalt
- 6. Equipment for SATS Test Stainless Steel Pressure Vessel (100
mm indiameter and 65 mm thick) Manual Back Pressure Regulator
600psi pressure transducer Temperature display module Balance
Vacuum Pump
- 7. SATS TEST PARAMETERS Specimen size= (100 mm in diameter and
60 mm thick) Air voids = 8% Binder content = 4% Temperature = 85 C
Pressure = 2.1 MPa (21 bar) Test duration = 65 h + 24 h Saturation
with Vacuum= 68 3 kPa for 30 min.YOUNG KYU CHOI UNI OF
NOTTINGHUM
- 8. SATS TEST PROCEDURE: Theunconditioned (initial) stiffness
modulus at 20 0.5C is determined under standard test conditions in
the Nottingham Asphalt Tester (NAT). (ITSM1). The dry mass of each
specimen is determined by weighing. The specimens are saturated
under distilled water at 20 1C, using a partial vacuum pressure of
68 3 kPa for 30 min.
- 9. CONTINUE Remove surface water, the wet mass of each specimen
is determined by weighing, and the percentage saturation is
calculated (this is termed initialsaturation). The pressure vessel
is partially filled with distilled water until the level is between
the fourth and fifth specimens . The vessel and water are
maintained at the target temperature (85C) for at least 2 h before
the conditioning procedure commences. The saturated specimens are
placed into the vessel, using the specimen tray, and the
conditioning procedure is performed at a pressure of 2.1MPa and a
temperature of 85C for 65 h.
- 10. CONTINUE After the test period, when the pressurevessel
display temperature has reduced to 70 C (this may take up to 3 h),
the specimens are extracted and surface-dried. The mass is
determined by weighing, and the percentage saturation is calculated
(this is termed retained saturation). The specimens are conditioned
at 20 C, and the conditioned (final) stiffness modulus is
determined under standard test conditions in the NAT.30
(ITSM2)
- 11. CONTINUE The final stiffness modulus divided bythe initial
stiffness modulus is calculated (this is termed retained stiffness
modulus) Retained stiffness= ITSM1 / ITSM2
- 12. RETAINED STIFFNESS VS RETAINED SATURATIONS 1 0.9 0.8 0.7
0.6 0.5 0.4RETAINED STIFFNES (%)0.3 0.2 0.1 0 01020304050RETAINED
SATURATIONS (%)YOUNG KYU CHOI UNI OF NOTTINGHUM60
- 13. EFFECT OF ACIDIC VS BASIC AGGREGATES For the mixtures
containing the acidicaggregate, the retained stiffness modulus
reduce from approximately 06 at a retained saturation level of 10%
to 02 at a retained saturation level of between 80% and 100%. At a
retained saturation level of 40% the retained stiffness modulus is
approximately 04.
- 14. CONTINUE For the mixtures containing the basic aggregate,
theretained stiffness modulus remains at an approximately constant
value of 07 over a wide range of retained saturation levels
(between 15% and 80%) Indicating that basic aggregates have lower
sensitivity to moisture.Collop, A.C. Development of the Saturation
Ageing Tensile Stiffness (SATS) Test
- 15. SATS TEST APPARATUS
- 16. REFRENCES: Collop, A.C. Development of the Saturation
Ageing Tensile Stiffness (SATS) Test. in Proceeding of the
Institution of Civil Engineers Transport 157. 2004. Development of
SATS Test for HMB By YOUNG KYU CHOIUNIVERSITY OF NOTTINGUM
- 17. Surface energy is the work per unit area done by the force
that creates the new surface.Units: dynes per centimeter. (dyn /cm)
Newton per meter (Nm-1) joule per meter square(j. m-2)1 dyn /cm is
equal to 0.001 Nm-1 or 1 mNm-1.
- 18. Continue. Typical surface energies (Source: Dr. B.R.Lawn).
materialSurface energy j.
m-2KCl0.11Zn0.11Mica0.38Glass4.4Limestone24Granite200.Fe (Cast
Iron)1520From the table, the surface energy is very large for Cast
Iron, which is a brittle material that shatters without much
warning. Since brittlefracture creates new surfaces, the surface
energy varies inversely with the tendency to brittle failure.
- 19. Surface Energy and Temperature In the bulk, atoms are
evenly surrounded and thecohesive forces between the atoms tend to
balance. On the surface there are atoms on one side only, so there
is a net inward cohesive force. This creates a force on the surface
that tries to minimize its area.
- 20. Continue When considered as a force rather than anenergy,
the force is called "surface tension". As temperature increases,
the atoms in a solid vibrate more, and reduce the cohesive force
binding the atoms. The surface energy depends on the net inward
cohesive force and so surface energy decreases with increasing
temperature.
- 21. Measuring the surface energy of solids 1. Fracture method:
A crack is opened up by forces pulling the edges apart. A "double
cantilever" forms. The work done by the applied force is equal to
the potential energy of the "leaf springs" and the surface energy.
Solving for the surface energy gives:
- 22. Continue 2. Indentation method With small specimens an
indentation method is used. A diamond point is forced into the
surface and micro cracks appear at the sharp edges. Measuring the
lengths, a,and c, and the indenting force, F, will give the surface
energy.
- 23. Illustration of a conical indenter forced into a
wafersurface. Optical micrograph of an indent introduced at room
temperature, using a conical indenter forced into the plane Several
cracks are initiated from the indent.
- 24. 3. Angle of contact For a solid/liquid/gas interface, the
adhesion between the liquid and the solid will curve the liquid
surface to form a crescent type shape(meniscus). The angle of
contact is always measured through the liquid.
- 25. FSG is the upward force between the solid and thegas. FSL
is the downward force between the solid and the liquid. FLG is the
inclined force between the liquid and the gas.
- 26. If cohesive force < adhesive forcecohesive force >
adhesive force
- 27. Surface energy of liquids In dealing with liquids, it is
more usual to use theidea of Surface Tension rather than Surface
energy, even though they refer to the same dimensional quantity.
This is shown in the following dimensional analysis.
- 28. 1. Capillary Action As a result of surface tension acting
around the inner circumference of a small-bore tube (or capillary),
that is partially immersed in a liquid, there will be a raised or
depressed column of liquid inside it. The upward component of the
surface tension force will balance the weight of the liquid
column.
- 29. The case of a raisedcolumn is shown on the right. The
upward component of the surface tension force will balance the
weight of the liquid column. The case of a raised column is shown
on the right. The upward component of the surface tension force
will balance the weight of the liquid column.
- 30. 2.Wilhelmy Plate Method A thin plate that is used to
measure equilibrium surface or interfacial tension at an airliquid
or liquidliquid interface. The plate is kept perpendicular to the
interface and force exerted on it is measured. L the wetted
perimeter (2w + 2d) of the Wilhelmy plate and is the contact angle
between the liquid phase and the plate. The force on the plate due
to wetting is measured via a tensiometer or microbalance.
- 31. Wilhelmy Plate Method
- 32. 3. Pendant Drop Method A drop of liquid is suspended from
the end of a tubeby surface tension. The force due to surface
tension is proportional to the length of the boundary between the
liquid and the tube, with the proportionality constant usually
denoted . Since the length of this boundary is the circumference of
the tube, the force due to surface tension is given by: F= d
- 33. The mass m of the tube can be found by equatingthe force
due to gravity (Fg = mg) with the component of the surface tension
in the vertical direction (Fsin) giving the formula mg= d Where is
the angle of contact with the tube, and g is the acceleration due
to gravity. The limit of this formula, as goes to 90 , gives the
maximum weight of a pendant drop for a liquid with a given surface
tension,
- 34. Pendant Drop Apparatus
- 35. References Butt, HJ.; Graf, K.; Kappl Physicsand Chemistry
of Interfaces, 2nd Edition (WiletVCH: Weinheim 2006). Gould, R.F.
1964. Contact angle wettability and adhesion American Chemical
Society, USA. Peter's Physics Pages Lecture 8