CIV3703 Transport Engineering
CIV3703 Transport Engineering
Module 4 – Part 2 Road Materials Dr. Andreas Nataatmadja
Construction of Sprayed Seal
Construction of Asphalt Surface
4.11 Bituminous Materials Composition: Physical state:
mainly hydrocarbons black or brown viscous liquid or solid
Chemical properties:
- soluble in carbon disulphide - largely non-volatile - resistant to most acids and salts
A thermoplastic, viscoelastic adhesive (i.e. deformation and flow depend on temperature and rate of loading)
Desirable properties: - cheap, workable, strong, durable, impermeable, adhesive Durability: prone to slow deterioration when exposed to heat, light and air; leads to brittleness and hardness
4.12 Production of Bitumen Produced from suitable crude petroleum oils. Middle East, North and South American, and Central African crudes suitable. Residue from the distillation of crude.
4.13 Testing of Bitumen
Classification of bitumen Based on viscosity at 60 degrees C. Class 50 Class 170 Class 320 Class 600
Comparison of Bitumen
Source: RMS-NSW
4.13.1 Viscosity Measure of shear resistance at a particular temperature. More viscous → thicker, more difficult to mix Less viscous → thinner, easier to mix Example: Class 170 bitumen 60°C viscosity 170 Pa.s. 135°C viscosity 0.4 Pa.s. Hence, needs heating to mix with aggregates Viscosity is measured with a viscometer.
Viscometer
4.13.2 Penetration Measures indentation of needle (specific dimensions) falling into the bitumen over a specified time period, at 15 and 25 deg. C. Penetration gives an indication of bitumen hardness.
Penetration Test AS 2341.12 100g; 5 sec; 25°C and 200g; 60 sec; 15 °C Penetration is expressed in 0.1 mm unit
4.13.3 Density Determined by density bottle: a small sample is weighed into a density bottle and the bottle is filled with water. The bottle is weighed at 15°C and bitumen density calculated. Hydrometers cannot be used because of the inaccuracies caused by bitumen on the stem and also because temperature corrections at high temperatures are not valid. Can also be measured using an electronic density meter. Gives an indication of source of crude. Typical figure: 1.02 to 1.04 at 15°C
4.13.4 Flashpoint Test To indicate safety limit to which bitumen may be heated. For straight bitumen, minimum flashpoint of 250°C usually specified. Flashpoint above 250 means material not classified as flammable.
4.13.5 Matter Soluble in Toluene Indicates purity of bitumen. The Australian test measures the percentage of matter insoluble in toluene. Most bitumens exceed 99.8 % solubility. Specifications usually > 99.0% solubility.
4.13.6 Effect of Heat and Air • Rolling Thin Film Oven (RTFO) test
In this test, a thin film of bitumen is continuously rotated around the inner surface of a glass jar at 163°C for 60 minutes. A jet of air is positioned to blow air, preheated to the oven temperature, into the mouth of each jar as it passes through the bottom of each rotation of the carriage that is being rotated at 15 revs/min.
Effect of heat and air
Source: RMS-NSW (2011)
4.14 Flux and Cutter Fluxing: addition of an oil which has long term effect on viscosity of binder. Diesel fuel oil often used.
Cutting: addition of an oil which has short term effect on viscosity of binder. Power kerosene and aviation jet fuel (Avtur) used.
Fluxing Fluxed bitumens used for: pothole patching mixes (have to be stored for weeks or months) sealing in cold climates during cooler months keeps bitumen fluid and prevents hardening in cold temperature; prevent loss of aggregate through bitumen brittleness at low temperature.
Cutting Cutback bitumens used: for temporary reduction of viscosity in sealing, keeps bitumen fluid for longer after it is sprayed, which allows slightly more time to incorporate aggregate particles. Fluxing and cutting can be done on site, or cutback bitumen can be refinery supplied.
IMPORTANT SAFETY POINT
Flashpoints of cutters and fluxes are low • •
Diesel fuel oil Power kerosene
75°C 38°C
STRICT SAFETY PROCEDURES NEED TO BE ADOPTED WHEN WORKING WITH THESE MATERIALS.
4.15 Cutback Bitumen Refinery cutbacks available (AS 2157). 3 categories: Slow curing (SC) – with fuel oil cutter Medium curing (MC) – with kerosene cutter Rapid curing RC - white spirit cutter (curing = time to return to original bitumen)
Medium Curing Cutbacks Typical Uses: AMC00, AMC0, AMC1 - Precoat, prime (Equiv. % kero: 56, 44, 34)
AMC2, AMC3, AMC4 - Primersealing (Equiv. % kero: 27, 21, 16)
AMC5, AMC6, AMC7 - Sealing (Equiv. % kero: 11, 7, 3)
4.16 Bitumen Emulsions Very fine droplets of bitumen suspended in a water base. Need an emulsifying agent to break bitumen into droplets. Need a stabilising agent to keep bitumen as droplets in drum.
Emulsions are very fluid - can be applied without heating.
Use of Bitumen Emulsion Used for cold application work: tack coats before asphalt manufacture of patching mixes stabilisation of crushed rock and sands slurry seals limited use for spray sealing (thin coats) When used, emulsion “breaks” - droplets join together, water evaporates -> bitumen
Emulsion Droplet 5 - 10µ µm
Types of Bitumen Emulsion Anionic Contains emulsion and stabilising agents of an alkaline nature, and has a bitumen content in excess of 60% classified according to setting (or breaking) time rapid (ARS) or slow (ASS) Cationic emulsion and stabilising agents of an acidic nature classified by setting time - CRS, CSS. also aggregate mixing, CAM, which contains oil.
Bitumen Emulsion -
Anionic • Rapid setting • Medium setting • Slow setting
-
-
ARS AMS ASS
-
-
-
-
-
-
-
-
Cationic • • • •
Rapid setting Medium setting Slow setting Aggregate mixing
+
CRS CMS CSS CAM
+
+
+
+
+
+
+
+ + +
+
Non-ionic • Medium setting
NMS
Break due to evaporation of water + Electrochemical attraction between soil, gravel or aggregate
4.17 Adhesion Agents Assist adhesion between pavement, binder and aggregate. Surface active adhesion agents are generally amine compounds. Performance of a particular adhesion agent depends on the aggregate, so testing is necessary. Applied to aggregate, or mixed in binder. Adhesion agent is not a substitute for precoating agent.
4.18 Precoating Materials Aggregate precoated to improve adhesion with binder. Materials used: AMC00 cutback special refinery cutbacks oil based materials some petroleum oil
Application: 4 to 12 litres per cubic metre
4.19 Polymer Modified Binder (PMB) Used in Australia since 1970s - usually natural or synthetic rubber (4 to 6% mass). PMBs now widely used. Usually used for a specific objective: rutting resistance, fatigue resistance and crack control in asphalt; crack control and aggregate retention in sprayed seals.
C170 vs. PMB
End Module 4, Part 2
Module 4 – Part 2 Road Materials Dr. Andreas Nataatmadja
Construction of Sprayed Seal
Construction of Asphalt Surface
4.11 Bituminous Materials Composition: Physical state:
mainly hydrocarbons black or brown viscous liquid or solid
Chemical properties:
- soluble in carbon disulphide - largely non-volatile - resistant to most acids and salts
A thermoplastic, viscoelastic adhesive (i.e. deformation and flow depend on temperature and rate of loading)
Desirable properties: - cheap, workable, strong, durable, impermeable, adhesive Durability: prone to slow deterioration when exposed to heat, light and air; leads to brittleness and hardness
4.12 Production of Bitumen Produced from suitable crude petroleum oils. Middle East, North and South American, and Central African crudes suitable. Residue from the distillation of crude.
4.13 Testing of Bitumen
Classification of bitumen Based on viscosity at 60 degrees C. Class 50 Class 170 Class 320 Class 600
Comparison of Bitumen
Source: RMS-NSW
4.13.1 Viscosity Measure of shear resistance at a particular temperature. More viscous → thicker, more difficult to mix Less viscous → thinner, easier to mix Example: Class 170 bitumen 60°C viscosity 170 Pa.s. 135°C viscosity 0.4 Pa.s. Hence, needs heating to mix with aggregates Viscosity is measured with a viscometer.
Viscometer
4.13.2 Penetration Measures indentation of needle (specific dimensions) falling into the bitumen over a specified time period, at 15 and 25 deg. C. Penetration gives an indication of bitumen hardness.
Penetration Test AS 2341.12 100g; 5 sec; 25°C and 200g; 60 sec; 15 °C Penetration is expressed in 0.1 mm unit
4.13.3 Density Determined by density bottle: a small sample is weighed into a density bottle and the bottle is filled with water. The bottle is weighed at 15°C and bitumen density calculated. Hydrometers cannot be used because of the inaccuracies caused by bitumen on the stem and also because temperature corrections at high temperatures are not valid. Can also be measured using an electronic density meter. Gives an indication of source of crude. Typical figure: 1.02 to 1.04 at 15°C
4.13.4 Flashpoint Test To indicate safety limit to which bitumen may be heated. For straight bitumen, minimum flashpoint of 250°C usually specified. Flashpoint above 250 means material not classified as flammable.
4.13.5 Matter Soluble in Toluene Indicates purity of bitumen. The Australian test measures the percentage of matter insoluble in toluene. Most bitumens exceed 99.8 % solubility. Specifications usually > 99.0% solubility.
4.13.6 Effect of Heat and Air • Rolling Thin Film Oven (RTFO) test
In this test, a thin film of bitumen is continuously rotated around the inner surface of a glass jar at 163°C for 60 minutes. A jet of air is positioned to blow air, preheated to the oven temperature, into the mouth of each jar as it passes through the bottom of each rotation of the carriage that is being rotated at 15 revs/min.
Effect of heat and air
Source: RMS-NSW (2011)
4.14 Flux and Cutter Fluxing: addition of an oil which has long term effect on viscosity of binder. Diesel fuel oil often used.
Cutting: addition of an oil which has short term effect on viscosity of binder. Power kerosene and aviation jet fuel (Avtur) used.
Fluxing Fluxed bitumens used for: pothole patching mixes (have to be stored for weeks or months) sealing in cold climates during cooler months keeps bitumen fluid and prevents hardening in cold temperature; prevent loss of aggregate through bitumen brittleness at low temperature.
Cutting Cutback bitumens used: for temporary reduction of viscosity in sealing, keeps bitumen fluid for longer after it is sprayed, which allows slightly more time to incorporate aggregate particles. Fluxing and cutting can be done on site, or cutback bitumen can be refinery supplied.
IMPORTANT SAFETY POINT
Flashpoints of cutters and fluxes are low • •
Diesel fuel oil Power kerosene
75°C 38°C
STRICT SAFETY PROCEDURES NEED TO BE ADOPTED WHEN WORKING WITH THESE MATERIALS.
4.15 Cutback Bitumen Refinery cutbacks available (AS 2157). 3 categories: Slow curing (SC) – with fuel oil cutter Medium curing (MC) – with kerosene cutter Rapid curing RC - white spirit cutter (curing = time to return to original bitumen)
Medium Curing Cutbacks Typical Uses: AMC00, AMC0, AMC1 - Precoat, prime (Equiv. % kero: 56, 44, 34)
AMC2, AMC3, AMC4 - Primersealing (Equiv. % kero: 27, 21, 16)
AMC5, AMC6, AMC7 - Sealing (Equiv. % kero: 11, 7, 3)
4.16 Bitumen Emulsions Very fine droplets of bitumen suspended in a water base. Need an emulsifying agent to break bitumen into droplets. Need a stabilising agent to keep bitumen as droplets in drum.
Emulsions are very fluid - can be applied without heating.
Use of Bitumen Emulsion Used for cold application work: tack coats before asphalt manufacture of patching mixes stabilisation of crushed rock and sands slurry seals limited use for spray sealing (thin coats) When used, emulsion “breaks” - droplets join together, water evaporates -> bitumen
Emulsion Droplet 5 - 10µ µm
Types of Bitumen Emulsion Anionic Contains emulsion and stabilising agents of an alkaline nature, and has a bitumen content in excess of 60% classified according to setting (or breaking) time rapid (ARS) or slow (ASS) Cationic emulsion and stabilising agents of an acidic nature classified by setting time - CRS, CSS. also aggregate mixing, CAM, which contains oil.
Bitumen Emulsion -
Anionic • Rapid setting • Medium setting • Slow setting
-
-
ARS AMS ASS
-
-
-
-
-
-
-
-
Cationic • • • •
Rapid setting Medium setting Slow setting Aggregate mixing
+
CRS CMS CSS CAM
+
+
+
+
+
+
+
+ + +
+
Non-ionic • Medium setting
NMS
Break due to evaporation of water + Electrochemical attraction between soil, gravel or aggregate
4.17 Adhesion Agents Assist adhesion between pavement, binder and aggregate. Surface active adhesion agents are generally amine compounds. Performance of a particular adhesion agent depends on the aggregate, so testing is necessary. Applied to aggregate, or mixed in binder. Adhesion agent is not a substitute for precoating agent.
4.18 Precoating Materials Aggregate precoated to improve adhesion with binder. Materials used: AMC00 cutback special refinery cutbacks oil based materials some petroleum oil
Application: 4 to 12 litres per cubic metre
4.19 Polymer Modified Binder (PMB) Used in Australia since 1970s - usually natural or synthetic rubber (4 to 6% mass). PMBs now widely used. Usually used for a specific objective: rutting resistance, fatigue resistance and crack control in asphalt; crack control and aggregate retention in sprayed seals.
C170 vs. PMB
End Module 4, Part 2
