BAHAN PERKERASAN MODUL ASPAL

1. BAHAN PERKERASANMODUL ASPAL

2. JENIS ASPAL • Aspal / bitumen / asphalt cement (AC) / penetration grade adalah bahan pengikat (binder) bahan perkerasan yang mempunyai sifat utama warna hitam (umumnya) dan sensitif terhadap suhu. • Jenis-jenis aspal: • Aspal bumi (fosil) atau bitumen • Tars • Aspal natural (Natural bitumen): aspal buton • Biobitumen (aspal dari tumbuhan)

3. BITUMEN MANUFACTURE • Crude oil is refined by fractional distillation to separate gas, gasoline, kerosine, gas oil and long residue. • The long residue is then redistilled under vacuum at 350-400 C to produce short residue. • The short residue consist of many different grades of bitumen • In many case, the vacuum residues are processed by air ratification (blowing) to produce harder penetration grade bitumens • The harder bitumens can then be blended with softer bitumens to produce intermediate grades

4. PROPERTY REQUIREMENT FOR PENETRATION GRADE BITUMEN • Penetration at 25oC • Softening point oC min and max • Ductility • Loss on heating for 5hr at 163oC - Loss by mass % (max) - Drop in penetration % (max) • Solubility in trichloroethylene % by mass (min) • Permitivity at 25oC and 1592 Hz (min)

5. CHARACTERISATION OF BITUMENS • The behaviour of bitumen is complex. • It is required a large number of tests to describe the properties of bitumen over a wide range of operating conditions (temperature, stress, strain rate). • To simplify, the mechanical behaviour of bitumen is described using emperical tests and equations. • The basic tests used are: - Penetration test (low temperature range <60oC) - Softening point test (low temperature range <60oC) - Viscosity test (high temperature range >60oC)

6. PENETRATION TEST • This is an empirical test • To be approximately equivalent to a measurement of ‘stiffness’ at a loading time of 0.4 seconds. • The penetration is the consistency expressed as the distance in tenths of a millimetre that a standard needle, of 100g, will penetrate vertically into a sample of bitumen at 25oC in 5 seconds.

7. PENETRATION TEST Digital Manual

8. PENETRATION TEST Penetration in unit of 0.1mm 100g 100g Aspal (25oC) Aspal (25oC) Start After 5 seconds

9. SOFTENING POINT TESTRing and ball test • Two steel balls are placed on two discs of bitumen contained within metal rings. These are raised in temperature at a constant rate (5oC/min) in a water bath. The softening point is the temperature (oC) at which the bitumen softens enough to allow the balls enveloped in bitumen to fall a distance of 25mm and hit a plate. • The softening point is approximately the temperature at which the penetration is 800, hence the notation T800PENis used to described the softening point

10. VISCOSITY • Viscosity of a fluid is a measure of its resistance to tangential or shear stress. It arises from interaction and cohesion of fluid molecules. All real fluids possess viscosity, though to varying degrees. The shear stress in a solid is proportional to strain whereas the shear stress in a fluid is proportional to the rate of shearing strain. It follows that there can be no shear stress in a fluid which is at rest (Webber, 1974).

11. VISCOSITY • As an example, a fluid confined between two plates which are situated a very short distance y apart. The lower plate is stationary whilst the upper plate is moving at velocity v. The layer adjacent to the stationary plate is at rest whilst the layer adjacent to the moving plate has a velocity v. The rate of shearing strain or velocity gradient is dv/dy. • The (dynamic) viscosity, µ, is expressed in mN s/m2 or centipoises (ML-1T-1) and given by µ = Shearing stress/rate of shearing strain

12. VISCOSITY • Absolute viscosity is measured by pulling the bitumen through the viscometer with a vacuum. • Kinematic viscosity express the bitumen flow under its own weight. • Viscosity at temperature >60oC is determined using rotational viscometer (Brookfield viscometer). • Viscometer at low temperature (< 60oC) and wide range of loading time can be measured using DSR.

13. KINEMATIC VISCOSITY Viscosity is also expressed as kinematic viscosity, v, in which density is considered in the form µ/ρ. Kinematic viscosity is expressed in mm2/s (L2T-1) or centistokes where it is independent of force. The kinematic viscosity of a liquid reduces with increasing temperature. The kinematic viscosity of water at 15oC is about 1.14 mm2/s. At room temperature the kinematic viscosity of air is about 13 times that of water.

14. Brookfield viscometerRotational viscometer

15. DSR (Dynamic Shear Rheometer)to measure viscosity of bitumen

16. THE BITUMEN TEST DATA CHART (BTDC) • BTDC was developed by Heukelom. • BTDC is a chart to express the relationship between penetration and absolute viscosity (Poises). • There are two equi-viscous lines on the chart, one occuring at a penetration of 800 representing the softening point and another at a penetration of 1.25 representing the Fraass breaking point (an estimate temperature at which a thin film of bitumen might crack). • Generally bitumen produce data that plot as a straight line on the chart.

17. TEMPERATURE SUSCEPTIBILITY (TS) The consistency of bitumens varies with temperature. This depends on the type and grade of bitumen. Temperature susceptibility (TS) is expressed by Penetration Index (PI) that developed by Pfeiffer & Van Doormaal. TS of a bitumen can be seen on the BTDC as a straight line with equation: Log P= A*T + K P= Penetration; A= slope of line

18. TEMPERATURE SUSCEPTIBILITY (TS) Log (800) – log (P @ 25 C) A= TSP – 25 C Log P Because value A is too small and this is inconvenient, so that PI was developed to indicate the temp susceptibility Pen 20 (1 – 25A) PI= 1 + 50 A P=800 Higher PI means harder bitumen 25 C TSP Temperature

19. DETERMINING Penetration Index (PI) Penetration at 25oC (dmm) Softening Point oC The arrow indicates the value increases PI Softer bitumen

20. MECHANICAL PROPERTIES OF BITUMEN STIFFNESS OF BITUMEN (Sb) Sb = Stress/ strain Sb can be measured using DSR Empirical equation: Loading time (sec)= 1/ Traffic speed (km/hr)

21. EFFECT OF LOADING TIME & TEMPERATURE ON BITUMEN STIFFNESS (Sb) Elastic asymptote Sb Sb Viscous asymptote T1 > T2 > T3 Loading time Loading time

22. DETERMINING bitumen stiffness • Measure using DSR (Dynamic Shear Rheometer) • Predict using Van der Poel Nomograph • Calculate using equation Using equation Sb= 1.157 * 10-7 * t-0.368 * 2.718-PI (SP-T)5 Only applicable where: Loading time (t)= between 0.01 and 0.1 seconds Penetration Index (PI)= between -1.0 and +1.0 Temperature difference (SP-T)= between 20C and 60C Sb in MPa; SP= softening point; T=temperature

23. DETERMINING Bitumen Stiffness (Sb) Sb Van der Poel Nomograph The arrow indicates the value increases PI Temperature difference oC Above T800 pen Below T800 pen Loading time (t)

24. MODIFIED BITUMEN Bitumen can be modified by adding an additive or modifier in order to improve its mechanical properties, for examples: • Obtaining stiffer asphalt mixture at high temperature to minimise rutting • Obtaining softer asphalt mixture at low temperature to minimise thermal cracking • Improving fatigue resistance • Improving bonding between aggregate and bitumen to reduce stripping or moisture susceptibility • Improving abrasion resistance of mixture to reduce ravelling • Rejuvinating aged bitumen • Permitting thicker bitumen film to increase the mixture durability • Reducing flushing or bleeding • Improving resistance to ageing or oxidation

25. BITUMEN ADDITIVES OR MODIFIERS • Filler: lime, Portland cement, fly ash • Rubber: natural latex, synthetic latex, reclaimed rubber • Plastic • Combination rubber and plastic • Fibre: rock wool, asbestos, cellulose • Hydrocarbon: recycling and rejuvinating oils, natural asphalt (trinidad lake asphalt, buton asphalt) • Waste materials: recycled tyres

26. TES OTAK KIRI BACA WARNANYA, BUKAN WORDNYA KUNINGMERAHHIJAU HITAM BIRU ORANYE COKLATJINGGAABU-ABU

27. tugas TULIS TANGAN BUAT PAPER TENTANG ASPAL (5 pages – kertas folio bergaris) Latar belakang Isi Kesimpulan Daftar pustaka