1. 1. Presented By: KHALID MEHMOOD 2K13-FT-MSC-TRAN-06 TANVEER UL HAQ2K13-PT-MSC-TRAN-11
2. 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. 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. 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. 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. 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. 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. 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. 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. 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. 11. CONTINUE The final stiffness modulus divided bythe initial stiffness modulus is calculated (this is termed retained stiffness modulus) Retained stiffness= ITSM1 / ITSM2
12. 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. 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. 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. 15. SATS TEST APPARATUS
16. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 26. If cohesive force < adhesive forcecohesive force > adhesive force
27. 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. 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. 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. 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. 31. Wilhelmy Plate Method
32. 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. 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. 34. Pendant Drop Apparatus
35. 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