9_Proteau_Microsurfacing Type IV, IsSA Palm Springs 2013

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New Grading curve for Microsurfacing ISSA annual meeting, Indian Wells 2013

New grading curve for Microsurfacing Presentation agenda

High skid resistance microsurfacing mix; Gap-graded gradation approach Aggregates and special gradation Performance of Gap-graded aggregates formulation

The use of synthetic Fibers; Microsurfacing machine modifications;

Fibers dosing unit;

Technical specifications proposal; A143 Recommended performance guideline

Modifications proposal

Recommendations

Type IV, specifications proposal Gap-graded gradation approach

Components of Gap graded micro-surfacing

Binder : PMA emulsion (EVA, SBS, LATEX)

Hard Aggregates: Blend of 2 differents sizes Selected Fibers

Type of fibers Dosing of fibers

Effect of fibers on the mix The very dense fiber network significantly modifies the rheological behavior of the mix,

giving short and long-term benefits. The addition of fibers increases the apparent viscosity of the mix. The apparent viscosity

increases by a factor of ten. This fibers network avoid any segregation in the spreader box, allowing the use of special Gap graded gradation.

Type IV, specifications proposal High skid resistance microsurfacing mix

Indian Wells, February 2013– page 4

Aggregates and special gradation: TEST TEST METHOD SPECIFICATION

Sand equivalent Value of soils and fine aggregates

ASTM D2419 65 % minimum

CPP (Polissing Coefficient by projection) PVN

LC 21-102 0.45 minimum

Resistance to degradation in Micro-deval machine

LS 609 16 % maximum

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0.01 0.1 1 10Sieves (mm)

Pass

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ISSA Type III gradation

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Gap graded 0-6.3 mm



Performances of Gap graded aggregates formulations:

Surface characteristics: Macro-texture, average texture depth, Sand patch test (initial)

0/6 mm (0-1/4 ) ATD > 1.0 mm 0/10 mm (0- 3/8) ATD > 1.2 mm

Skid resistance (initial) BFC at 40km/h > 0,50 BFC at 120km/h > 0,35 BPN > 0.70 Higher the grading, higher the BFC

Le Réseau

A Gripfibre® 0/10 has been laid on a section of A71 highway (2 km). Braking-force coefficient has been measured after 6 and 18 months.

Novmember 2011 – page 6

Gripfibre® product

Type IV , specifications proposal

0.1

0.2

0.3

0.4

0.5

0.6

0.7

40 50 60 70 80 90 100 110 120

Brak

ing-

forc

e co

effic

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(BFC

)

Speed (km/h)

Evolution of braking-force coefficient on motorway A71 after 6 and 18 months of service

BFC after 6 months on slow lane

BFC after 18 months on slow lane

BFC after 6 months on fast lane

BFC after 18 months on fast lane

Upper and bottom thresholdsmeasured on national roads

High skid resistance microsurfacing mix

Type IV, specifications proposal The use of synthetic fibers


The use of synthetic fibers: Synthetic organic fibers

0.1 to 0.2% in relation to aggregates Thin and long (4 to 6 mm) Several million of fibres per m² Pretreated for a better dispersion

Use of a Fiber Cutter system Laying made easier

Against segregation and trickles

Improved performances Allow gap-graded formulas to be used Ensure a better long lasting skid resistance

Type IV, specifications proposal Microsurfacing machine modifications


Fibers specially designed dosing unit: Hydraulic motor

Upper cakebreaker

Lower cakebreaker Spiral elements

Dosing plate

Hydraulic motor

Upper cakebreaker

Lower cakebreaker Spiral elements

Dosing plateReady to use Fibers

Type IV, specifications proposal Technical specifications proposal


A143 Recommended performance guideline:



Modifications proposal: 4.1 Materials

4.1.2 Quality tests

4.2 Aggregate 4.2.1 General

59% Minimum

RAP,



Modifications proposal: 4.2 Aggregate

4.2.2 Quality tests

TEST TEST AASHTO

METHOD ASTM

SPECIFICATION

Accelerated Polishing of Aggregates Using the British Wheel*

T 279-96 D 3319-90

0.45 minimum

Resistance of Coarse Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus

T 327-09 D 6928-03 15 % maximum

Supplementary specifications applicables to type IV mix

*The polishing test is run on the parent aggregate




4.2.3 Gradation SIEVE

SIZE TYPE II

PERCENT PASSING

TYPE III PERCENT PASSING

TYPE IV PERCENT PASSING

STOCKPILE TOLERANCE

3/8 (9.5 MM) 100

100 100

1/4 (6.3 MM) 70 - 90

# 4 (4.75 MM) 90 - 100 70 - 90 35 - 60 ± 5%

# 8 (2.36 MM) 65 - 90 45 - 70 35 - 50 ± 5%

# 16 (1.18 MM) 45 - 70 28 - 50 25 - 40 ± 5%

# 30 (600 µm) 30 - 50 19 - 34 20 - 30 ± 5%

# 50 (330 µm) 18 - 30 12 - 25 15 - 25 ± 4%

# 100 (150 µm) 10 - 21 7 - 18 7 - 18 ± 3%

# 200 (75 µm) 5 - 15 5 - 15 5 - 15 ± 2%


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Gap graded TYPE IV




4.2.3 Gradation Type IV. This special fibrous gap-gradation provides a very high average texture depth of > 1.0 mm (ASTM E965) in order to obtain a very good skid resistance on pavement high speed trafic. Use of hard aggregate and resistant to polishing ensures the long-term high skid resistance between the wearing course surface and tyres. The fibers within the microsurfacing modify its rheology and characteristics, both in the short and the long term. It also allows the laying of gap-graded formula without segregation. This type of micro surfacing is appropriate for all levels of trafic, highways, bridges resurfacing and intersections.

4.6 Synthetic fibers The fibers are organic or synthetic. They have to ensure a good dispersion in the mix during the mixing operation.



Modifications proposal: 5.2 Mix design

Fibers 0.1 – 0.2 % by dry weight of aggregates



Modifications proposal: 6.2 Mixing equipment

In the production of type IV mix, the fibers must be assayed using a specially designed independent dosing has this effect. Rate control will be determined by volumetric way.



Modifications proposal: 11.2 Rate of application

Type IV Primary and Interstate roads, Bridges, Intersections

Wheel ruts Scratch or leveling Course

18 – 32 lb/yd² (10.0 - 18.0 kg/m²)

Type III as required (See appendix B)

Type III as required

Type IV, specifications proposal Recommandations


Recommandations: The rut fill have to be realized with type III mix; Recommandation to always realized a type III scratch coat before the application of Type IV mix wearing course; The fibers dosing unit have to be specially designed to this application; Aggregates gradation for gap-graded mix:

Blend of 0 -1/8 and 1 /4 - 3/8:

AGGREGATES EXAMPLE #1 EXAMPLE #2

0 – 1/ 8 35-45 % 35-45 %

1 /4 - 3/8 STONE 55-65 % 30-35 %

1 /4 - 3/8 RAP 20-35 %

Le Réseau

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9_Proteau_Microsurfacing Type IV, IsSA Palm Springs 2013