CIV3703 Transport Engineering
CIV3703 Transport Engineering Module 5A Design of Bituminous Surfacings – Part A
Dr. Andreas Nataatmadja
5.1 Types of Bituminous Surfacings Purpose of bituminous surfacing: shield pavement from traffic wear; eliminate dust -> improve road user, comfort, safety; providing unchanging surface in all weather; provide reasonable travel speed; reduce maintenance requirements; prevent moisture penetration into pavement.
5.1.1 Sprayed Treatments Further subdivision: 1. Primes – preliminary, before more permanent cover 2. Primerseals - temporary treatment with aggregate 3. Seals - permanent cover 4. Reseals - seal on an existing seal 5. Surface Enrichment - light binder applied to existing seal.
Seals (Permanent Covers) Three types commonly used one application of binder and one layer of aggregate (single/single) one application of binder and two layers of aggregate (single/double) two applications of binder and two layers of aggregate (double/double) (binder, 1st aggregate, binder, 2nd aggregate)
Single/Single Seal (S/S)
Single/single:
Most common economical type of seal new work and reseal treatments
Binder:
C170, PMB
Aggregate:
7/10/14/16/20mm
Reference:
This lecture is based on “Practitioner’s Guide to Design of Sprayed Seals – Revision 2000 Method” – Austroads (2002). Current guide: “Update of the Austroads Sprayed Design Method” - Austroads (2006).
Single/Double Seal (S/D)
Single/Double:
One application of binder and two layer of aggregate
Binder:
C170, PMB
Aggregate:
1st layer is larger aggregate 2nd layer is ideally half size of 1st layer
Combinations:
20/10, 20/7, 14/7, 10/5 mm
Note: If not enough binder then more likely windscreen breakage
Double/Double Seal Double/double:
Better than a S/S for areas of high traffic loading & shear stress (intersections, steep grades, tight curves)
Application:
2 layers of binder, and 2 layers of aggregate
Binder:
C170, PMB
Aggregate:
1st layer is larger aggregate 2nd layer is ideally half size of 1st layer e.g. 20/10, 20/7, 14/7, 10/5 mm
Reference:
“Update of the Austroads Sprayed Seal Design Method” – Austroads (2006). This has been superseded by “Update of Double/Double Design for Austroads Sprayed Seal Design Method” – Austroads (2013)
Resealing Seal on an existing seal to maintain the assets. Generally S/S is adequate. Cutback bitumen or Bitumen Emulsion can be used.
Surface Enrichment spraying of a light grade of cutback bitumen or emulsion with no aggregate binder runs into the voids between the existing seal stones extends the life of surface traffic has to be diverted for some time
Asphalt A mixture of aggregate and bituminous binder, usually produced in a mixing plant. Asphalt (AUS) = asphalt(ic) concrete (USA), bituminous concrete, hotmix Bitumen (AUS) = asphalt cement (USA)
Uses of Asphalt Construction of a new pavement; Strengthening an existing pavement; Correcting irregularities in an existing pavement; Repairing an existing pavement; Providing a new wearing surface.
Asphalt Types Dense Graded Mix usual type grading of aggregate sizes from fine to coarse stability depends on grading, binder content, air voids and density Open Graded Mix high air voids, stability depends on interlock Gap Graded Mix stability depends on the stiffness of aggregate-binder mix
5.2 Selection of Surfacing Type Factors influencing selection: the pavement structure economic and financial considerations riding quality, tolerable roughness pedestrian use safety noise generation plant, material availability waterproofing requirements
5.3 Design of Sprayed Surfacings
5.3.1 Selection of Primer and Application Rate
Preliminary cover prior to applying more permanent cover. Functions of a prime: provide bond between pavement and seal coat; minimise effect of dust after sweeping; strengthen pavement surface by increased cohesion; provide short term running surface prior to sealing; allow proof testing of pavement; act as waterproof membrane which assist in stabilising the pavement moisture condition
Primer Primer:
Typically cutback bitumen, (AMC00 – AMC1) or Specially formulated emulsion primer
Selection:
Based on knowledge and experience
Rates:
Application rates vary from 0.6 L/m2 (damp pavement) to 1.3 L/m2 (dry pavement)
PRIME is preferred treatment for new roads before more permanent cover (only for limited trafficking).
5.3.2 Selection of Primerseals Aim:
1. Temporary treatment to carry traffic several months. 2. Allows the normal seal coat to be applied in more favourable weather.
Primerbinders: Typically cutback bitumen (AMC 4 or 5) Winter use: 15% cutter: Summer use: 10% cutter CRS emulsion (60 & 70% bitumen) can be an alternative Base rates plus allowances. Typically 1.2 – 1.4 L/m² Aggregate:
5, 7 & 10 mm (usually less than 7 mm)
Typical life: Up to 12 months Apply final permanent cover to complete the treatment.
5.3.3 Design of Seals and Reseals 1. Select type of seal. single/single; single/double; double/double 2. Select aggregate size. Depends on the type of treatment; traffic; noise; pavement condition; alignments. For two aggregate coasts: 2nd half size of the first. 3. Select aggregate type.
4. Select aggregate application rate. Larger aggregate (≥ 10 mm): • Conventional bitumen: 900 / ALD (m2/m3) • Polymer modified binder: 750 / ALD (m2/m3) For 7 mm aggregate: 200 to 250 (m2/m3) Allow allowances for loss: spreading, whip-off; stockpile. Typical: 5% for 20mm; 10% for 7mm Multiple application work: 1st - as for single/single 2nd - past experience/trials (70% single/single ?)
5. Select binder type. Bitumen; cutback bitumen; multigrade bitumen; fluxed bitumen; bitumen emulsion; polymer modified binders. Most common in Australia: C170, some C320 in hotter areas Flux - usually maximum of 5% by volume. Cutter - mainly depends on road/air temperatures and traffic volume. Use Fig. 5.3 to determine quantity.
6. Select binder application rate. Basic application rate (litres per square metre) = ALD x Void Factor (VF) Void Factor (VF) = Vf + Va + Vt Vf – Basic Voids Factor (based on traffic volume) Va – Aggregate adjustment Vt – Adjustment for traffic effects
Basic Void factor
Upper limit: Bleeding Lower limit: Stripping
Table 5.6 Aggregate Adjustment (Va)
Table 5.7 Traffic Effects Adjustment (Vt)
Example Design the surfacing for New England Highway, 8 km north Warwick Reconstruction: 2 km length, 2 lane road Traffic: 3800 vehicles per day Pavement condition: “Hungry” Basalt aggregate available: Nominal size ALD (mm) 20 mm 12 mm 15 mm 10 mm 10 mm 7 mm 7 mm
1. Select Surface Treatment Prime and seal 2 coat seal (D/D) – why? Traffic: 3800 veh/day (includes 22% commercial)
2. Design of Prime
AMC00 AMC0 AMC1, AMC2
Porous surface: use heavy primer, AMC1 cutback bitumen Application rate 1.0 l/m2 Any aggregate?
3. Design of Seal - Aggregate Aggregate? (a) 20 mm + 10 mm Application? (b) 83 m2/m3 + 150 m2/m3 (including reductions)
3. Design of Seal - Binder Type? (c) Bitumen + Cutter How much cutter? Assume road temperature: 35°C Cutter: 2%
3. Design of Seal - Binder Application rate? Design void factor (VF) Application: 1.5 l/m2 + 1.0 l/m2
Summary Prime: AMC1 Seal – Class 170 bitumen + 2% cutter 1st coat: 20 mm aggregate @ 83 m2/m3 Binder 1.5 l/m2 2nd coat: 10 mm aggregate @ 150 m2/m3 Binder 1.0 l/m2
End of Module 5 – Part 1
Dr. Andreas Nataatmadja
5.1 Types of Bituminous Surfacings Purpose of bituminous surfacing: shield pavement from traffic wear; eliminate dust -> improve road user, comfort, safety; providing unchanging surface in all weather; provide reasonable travel speed; reduce maintenance requirements; prevent moisture penetration into pavement.
5.1.1 Sprayed Treatments Further subdivision: 1. Primes – preliminary, before more permanent cover 2. Primerseals - temporary treatment with aggregate 3. Seals - permanent cover 4. Reseals - seal on an existing seal 5. Surface Enrichment - light binder applied to existing seal.
Seals (Permanent Covers) Three types commonly used one application of binder and one layer of aggregate (single/single) one application of binder and two layers of aggregate (single/double) two applications of binder and two layers of aggregate (double/double) (binder, 1st aggregate, binder, 2nd aggregate)
Single/Single Seal (S/S)
Single/single:
Most common economical type of seal new work and reseal treatments
Binder:
C170, PMB
Aggregate:
7/10/14/16/20mm
Reference:
This lecture is based on “Practitioner’s Guide to Design of Sprayed Seals – Revision 2000 Method” – Austroads (2002). Current guide: “Update of the Austroads Sprayed Design Method” - Austroads (2006).
Single/Double Seal (S/D)
Single/Double:
One application of binder and two layer of aggregate
Binder:
C170, PMB
Aggregate:
1st layer is larger aggregate 2nd layer is ideally half size of 1st layer
Combinations:
20/10, 20/7, 14/7, 10/5 mm
Note: If not enough binder then more likely windscreen breakage
Double/Double Seal Double/double:
Better than a S/S for areas of high traffic loading & shear stress (intersections, steep grades, tight curves)
Application:
2 layers of binder, and 2 layers of aggregate
Binder:
C170, PMB
Aggregate:
1st layer is larger aggregate 2nd layer is ideally half size of 1st layer e.g. 20/10, 20/7, 14/7, 10/5 mm
Reference:
“Update of the Austroads Sprayed Seal Design Method” – Austroads (2006). This has been superseded by “Update of Double/Double Design for Austroads Sprayed Seal Design Method” – Austroads (2013)
Resealing Seal on an existing seal to maintain the assets. Generally S/S is adequate. Cutback bitumen or Bitumen Emulsion can be used.
Surface Enrichment spraying of a light grade of cutback bitumen or emulsion with no aggregate binder runs into the voids between the existing seal stones extends the life of surface traffic has to be diverted for some time
Asphalt A mixture of aggregate and bituminous binder, usually produced in a mixing plant. Asphalt (AUS) = asphalt(ic) concrete (USA), bituminous concrete, hotmix Bitumen (AUS) = asphalt cement (USA)
Uses of Asphalt Construction of a new pavement; Strengthening an existing pavement; Correcting irregularities in an existing pavement; Repairing an existing pavement; Providing a new wearing surface.
Asphalt Types Dense Graded Mix usual type grading of aggregate sizes from fine to coarse stability depends on grading, binder content, air voids and density Open Graded Mix high air voids, stability depends on interlock Gap Graded Mix stability depends on the stiffness of aggregate-binder mix
5.2 Selection of Surfacing Type Factors influencing selection: the pavement structure economic and financial considerations riding quality, tolerable roughness pedestrian use safety noise generation plant, material availability waterproofing requirements
5.3 Design of Sprayed Surfacings
5.3.1 Selection of Primer and Application Rate
Preliminary cover prior to applying more permanent cover. Functions of a prime: provide bond between pavement and seal coat; minimise effect of dust after sweeping; strengthen pavement surface by increased cohesion; provide short term running surface prior to sealing; allow proof testing of pavement; act as waterproof membrane which assist in stabilising the pavement moisture condition
Primer Primer:
Typically cutback bitumen, (AMC00 – AMC1) or Specially formulated emulsion primer
Selection:
Based on knowledge and experience
Rates:
Application rates vary from 0.6 L/m2 (damp pavement) to 1.3 L/m2 (dry pavement)
PRIME is preferred treatment for new roads before more permanent cover (only for limited trafficking).
5.3.2 Selection of Primerseals Aim:
1. Temporary treatment to carry traffic several months. 2. Allows the normal seal coat to be applied in more favourable weather.
Primerbinders: Typically cutback bitumen (AMC 4 or 5) Winter use: 15% cutter: Summer use: 10% cutter CRS emulsion (60 & 70% bitumen) can be an alternative Base rates plus allowances. Typically 1.2 – 1.4 L/m² Aggregate:
5, 7 & 10 mm (usually less than 7 mm)
Typical life: Up to 12 months Apply final permanent cover to complete the treatment.
5.3.3 Design of Seals and Reseals 1. Select type of seal. single/single; single/double; double/double 2. Select aggregate size. Depends on the type of treatment; traffic; noise; pavement condition; alignments. For two aggregate coasts: 2nd half size of the first. 3. Select aggregate type.
4. Select aggregate application rate. Larger aggregate (≥ 10 mm): • Conventional bitumen: 900 / ALD (m2/m3) • Polymer modified binder: 750 / ALD (m2/m3) For 7 mm aggregate: 200 to 250 (m2/m3) Allow allowances for loss: spreading, whip-off; stockpile. Typical: 5% for 20mm; 10% for 7mm Multiple application work: 1st - as for single/single 2nd - past experience/trials (70% single/single ?)
5. Select binder type. Bitumen; cutback bitumen; multigrade bitumen; fluxed bitumen; bitumen emulsion; polymer modified binders. Most common in Australia: C170, some C320 in hotter areas Flux - usually maximum of 5% by volume. Cutter - mainly depends on road/air temperatures and traffic volume. Use Fig. 5.3 to determine quantity.
6. Select binder application rate. Basic application rate (litres per square metre) = ALD x Void Factor (VF) Void Factor (VF) = Vf + Va + Vt Vf – Basic Voids Factor (based on traffic volume) Va – Aggregate adjustment Vt – Adjustment for traffic effects
Basic Void factor
Upper limit: Bleeding Lower limit: Stripping
Table 5.6 Aggregate Adjustment (Va)
Table 5.7 Traffic Effects Adjustment (Vt)
Example Design the surfacing for New England Highway, 8 km north Warwick Reconstruction: 2 km length, 2 lane road Traffic: 3800 vehicles per day Pavement condition: “Hungry” Basalt aggregate available: Nominal size ALD (mm) 20 mm 12 mm 15 mm 10 mm 10 mm 7 mm 7 mm
1. Select Surface Treatment Prime and seal 2 coat seal (D/D) – why? Traffic: 3800 veh/day (includes 22% commercial)
2. Design of Prime
AMC00 AMC0 AMC1, AMC2
Porous surface: use heavy primer, AMC1 cutback bitumen Application rate 1.0 l/m2 Any aggregate?
3. Design of Seal - Aggregate Aggregate? (a) 20 mm + 10 mm Application? (b) 83 m2/m3 + 150 m2/m3 (including reductions)
3. Design of Seal - Binder Type? (c) Bitumen + Cutter How much cutter? Assume road temperature: 35°C Cutter: 2%
3. Design of Seal - Binder Application rate? Design void factor (VF) Application: 1.5 l/m2 + 1.0 l/m2
Summary Prime: AMC1 Seal – Class 170 bitumen + 2% cutter 1st coat: 20 mm aggregate @ 83 m2/m3 Binder 1.5 l/m2 2nd coat: 10 mm aggregate @ 150 m2/m3 Binder 1.0 l/m2
End of Module 5 – Part 1
