CIV-E1010 BuildingMaterials Technology- The bituminousMaterialsMichalina Makowska, M.Sc.

Imagine the world without asphaltroads…

8.10.20162

This may still be easy to do in Finland…

8.10.20163

”In the far away galaxy” outside ofKehä III, where ”the wolves runfree”

Kehä I - Turunväylä

Asphalt concrete is a civilisationalachievement which divides the world

8.10.20164

China

Prof.T. Pellinen

Function of bound surfaces: Provide smooth,safe, durable riding surface

Recreational FacilitiesArterial and Highways

Sports Facilities

Parking lots

Path Ways

Airfields

5

Asphalt also protects concretestructures from water action and salts

8.10.20166

Without it deterioration oflarge scale structures wouldbe faster

What an asphaltconcrete is made ofthat makes it special?

8.10.20168

Why no longer tar?

8.10.20169

What is asphalt concrete made of?

Bitumen4-10%

Aggregates (coarse and fine)90-95% by weight

(Cellulose)fibers0,5%

Mineral filler

Bitumen modifiers,e.g.

ELVALOY® Dupont

Prof.T. Pellinen

Nomenclature• In US

– Asphalt or Asphalt Cement is thebinder (liquid) à moving towards“bitumen”

– Asphalt Cement Concrete is the mixwith aggregate and binder

– Asphalt mix is typically called: HotMix Asphalt (HMA)

• In Europe and Latin America– Bitumen is the binder (liquid)– Asphalt or asphalt cement concrete is

the mix with aggregate and binder

10

Bituminous Materials• Natural or manufactured complex mixtures of

hydrocarbons (polymers)– Carbon constitutes 80-87% of the mixture while

hydrogen forms 9-11%.• Bituminous materials are divided into three

broad classes– Bitumen (asphalt), tars and pitches (carcinogenic,

not used today)• Bitumen can be found

– Natural deposits or– Can be manufactured from petroleum (main source

for paving industry)

11

Petroleum-Based Bitumen• Bitumen is waste product from

refinery processing of crude oil– Sometimes called the “bottom of the

barrel”

• Fractional distillation:– Process of separating different

materials from crude oil by heatingand removing the steam atsuccessive temperatures:

• Properties depend on:– Refinery operations– Composition crude source-

dependent

GasolineKerosene

Lt. Gas OilDiesel

Motor Oils

Bitumen

Barrel of Crude Oil

• Gasoline is distilled at 100-400° F (37-204°C)• Kerosene and diesel areremoved at higher temperatures• Asphalt cement requires 900 °F (255°C) to be distilled. 12

World Crude Oil Producers

OPEC (Organization of Petroleum ExportingCountries) 13

Global Bitumen Use

14

What is bitumenfrom the chemicalpoint of view?

Bitumen Composition/model• The Dispersed Polar Fluid (DPF) model assumes that

bitumen is a single-phase system i.e., a simplehomogenous liquid

• Colloidal model presumes that there are two phasespresent, a continuous, low-polar phase, and adispersed, highly polar phase.– Bitumen is a mixture of asphaltenes dispersed in an oily

medium (maltenes) composed of saturates, aromatics anddispersed part of resins.

• A new model was proposed in 2000 by Per Redelius(Nynas Oy), based on mutual solubility of solvents. Itincorporates information about cohesion, molecularvolume, dispersive and polar interactions as well ashydrogen bonding.

16

dDDispersive

Hansen Solubility Parameters in the context ofbitumen and other chemicals

8.10.201617

HSP of ethanol15.8, 8.8, 19.4

Aged bitumenSoft bitumen

Bitumen+ ethanol

HSP of heptane15.3, 0, 0

Bitumen+ heptane

HSP of chloroform17.8, 3.1, 5.7

Bitumen+ chloroform

d HH

-bon

ding

dPPolar

Rejuvenator – extension of the continuum of molecules– HSP within the HSP of bitumen

The asphaltenes and the maltenesdepend on the separation type

8.10.201618

(pentane as eluent) (heptane as eluent)

Source of picture: New Mexico Institute of Mining and Technology, guide to asphaltenes

SARA-fractioning

Eluents used in Nordic countries:- Hexan- Toluene- Methanol/dichloromethylen

Onset of instabilityInstable crude oil

Heptane/hexane/pentane have mutualsolubility with maltenes but precipitateasphaltenes

8.10.201619

dDDispersive

d HH

-bon

ding

dPPolar

HSP of heptane15.3, 0, 0

Per Redelius, Energy Fuels, 2004, 18 (4), pp 1087–1092Makowska, Pellinen, SIB2015, (2016)

What bitumen is? Nobody knows …- Bottom residue from the

distillation of crude oil (?)- Different crude = differet

product- Contains thousands (and

some claim milions) ofvarious molecules

- By definition they all (99%+)have to be soluble in toluene

- It consists of carbon,sulphur and oxygen

- It has asphaltenes

8.10.201620Heavy Petroleum Composition. 4. Asphaltene Compositional Space

Amy M. McKenna, Alan G. Marshall, and Ryan P. Rodgers, Energy Fuels 2013, 27, 1257−1267

It is not the size of the molecules…

Refinery Operation

FIELD STORAGEPUMPINGSTATION

LIGHT DISTILLATE

HEAVY DISTILLATE

PROCESSUNIT

ASPHALTCEMENTS

FOR PROCESSING INTOEMULSIFIED ANDCUTBACK ASPHALTS

STILL

AIR

AIRBLOWNASPHALT

STORAGE

TOWERDISTILLATIONREFINERY

RESIDUUM

OR

GAS

PETROLEUM

SAND AND WATER

CONDENSERSAND

COOLERS

TUBEHEATER

MEDIUM DISTILLATE

21

Natural asphaltsDifferent name is typically coming from area of excavation orcompany excavating it:e.g. Gilsonite, Trinidad Lake Asphalt, Selenizza Asphalt

• The product is not always 99% soluble in toluene (like bitumen),because of the sediment in it.

• Typically not purified or refined• May contain from 50 to 98% of asphaltenes and resins• High cracking temperature, but reinforces bitumen and increases

resistance to permanent deformation

8.10.201622

Other bituminousproducts

Cut-back Bitumen

• Cut-back bitumen is liquid bitumen blended with petroleumsolvents:

– When the solvents evaporate the remaining material is the highviscosity bitumen

– The process of evaporation of the solvent is known as curing– The rate of curing depends on the type of solvent

• Rapid-curing cut-back bitumen is produced when gasoline is usedas solvent (high rate of evaporation of gasoline)

• Medium-curing cut-back bitumen is blend of kerosene and asphaltcement

• Slow-curing cut-back bitumen is blend of diesel and bitumen

• Cut-back bitumen do not require heating. They are used in cold-laidpavement bases and proprietary permanent cold batchingcompounds. Another use is tack-coat and surface treatments.

24

Fluxed bitumen(Fluksatut bitumit)

• Blend of bitumen and relatively non volatile oils,• Typical fluxants include gas oil and vegetable

based oils• Used in soft patching mixtures• Used as rejuvenators in recycling

25

Modified bitumen(modifoidut bitumit)

• Polymer modified binders have allowed the use of techniques previously notpracticable, such as micro-surfacing and using emulsion chip seals on high trafficroads.

• Many of the Superpave binder grades require polymer modification to concurrentlymeet the requirements for high temperature resistance to rutting and lowtemperature resistance to thermal cracking.

• In general, elastomers (rubber) are chosen to give a more resilient, flexiblepavement, while

• plastomers (plastics) result in mixes with higher stabilities and stiffness moduli.• The results are highly dependent upon the concentration, the molecular weight,

the chemical composition, and the molecular orientation of a particular polymer aswell as the crude source, the refining process and the grade of the base asphaltused.

26

Modified bitumen – bitumen sharessome solubility with the polymer

8.10.201627

Polymer reinforces the bitumen,and becomes a part of it (swelling,solubility)

Polymer modified bitumen (PmB)is used for special applications:- Heavy traffic roads (U.S.A.)- Roofing shingles- Water protection of bridges

(replaced tar)

V. Mouillet et al. / Fuel 87 (2008) 1270–1280

Polymer modifiers• SBS = Styrene-Butadiene-Styrene• SB = Styrene-Butadiene

• EVA = Ethylene vinyl acetate• LDPE = Low Density Polyethylene

• Styrelf - SBS• Stylink –SB• Novophalt –LDPE• ELVALOY – ethylene copolymers

• Crumb Rubber Tires 28

Bitumen emulsions• Produced by breaking bitumen into very fine particles and dispersing these

in a mixture of water and emulsifying agent– Emulsifying agent facilitates the dispersion of asphalt particles in water

• The emulsion forms a layer on the bitumen particles:– Layer may be positively charged (cationic emulsion) (used with negative

charged Slilica aggregates)– Or negatively charged (anionic emulsion) (used with positively charged

limestone aggregate)• A normal emulsion generally contains 55% to 70% bitumen and 0.5% to

3% emulsifying agent. The rest is water.

• After the emulsified asphalt is sprayed onto a surface or mixed withaggregates the water evaporates (emulsion breaks) and leaves only theasphalt residue behind to cement the aggregates together or waterproofthe surface it was sprayed on.

• Used in road surfacing applications, such as surface dressing, coldmixtures and slurry seals.

29

Breaking of emulsion

Emulsion – the browncolor means that thewater is still present

Emulsion – the blackcolor means that the waterhas evaporated

30

Recycled bitumen

This material comes typically as a part of Recycled Asphalt Pavement(RAP) or Recycled Asphalt Shingles (RAS).

It is an aged bitumen, which was previously exposed to the oxygen,UV and thermal treatment (production, transport and laydown)à thistypically changes its rheological properties

Is not separated from aged asphalt before addition into the newmixture. But for the quality control, samples are extracted andcharacterized in order to determine rheological properties

8.10.201631

Bitumen is ”alive” – it consumes oxygen andages – changes its molecular composition

8.10.201632

The molecular distribution ofbitumen changes with age

The effect can be mitigated byrejuvenation or application ofantioxidants

But the introduced carboxyl andsulfoxyl groups are not removedand material has morehydrogen bonds

Analogy: methanà methanol

Figure. The Molecular Weight Distribution by GelPermeation Chromatography

What is bitumenfrom the physicalpoint of view

Bitumen is a viscoelastic material

8.10.201634

Elastic - deformation due to loading is recoverable – it is ableto return to its original shape after a load is removed

Viscous - deformation due to loading is non-recoverable – itcannot return to its original shape after a load is removed

Time, Temperature and Load determine its behavior

If the phase angle is 0 degrees the material isfully elastic and 90 it is viscous

8.10.201635

Higher G* = stiffermaterialà can endure more

stress

à Viscousproperties allowfor stressdissipation

DynamicShearRheometer

Aging causes loss of viscous response,rejuvenation restores the self-healing

8.10.201636Blomberg, Makowska, Pellinen, Laboratory simulation of bitumen aging and

rejuvenation to mimic multiple cycles of reuse, TRA 2016

RawAgedRejuvenatedRejuvenator

Bitumen can vary from solid to semisolid to liquid depending on temperature

Bitumen grading

Consistency• Consistency is the measure of the degree of

fluidity or plasticity of the asphalt at anyparticular temperature:– Consistency is measured indirectly by either

measuring viscosity or penetration– Direct measurement is the shear (complex) modulus

of the asphalt |G*| which is a function of shear stress(t0) and shear strain (g0)

38

Penetration, Ring and Ball Softening Pointand viscosity are the tests used in Europe

8.10.201639

Recycling: The Ring and Ball Softening Point gives an indication of thetemperature at which the grains are easily separated, but the masticcomposition determines the exact temperature for the asphalt concrete

The Penetration grade specifies also viscosity,aging resistance, low temperature performance

8.10.201640Source: Finnish Asphalt Specifications 2000

The flash point in the context ofrecycling

8.10.201641

8.10.201642Source: Finnish Asphalt Specifications 2000

Recycling, how much fresh and old?

8.10.201643

If the Penetration of the bitumenrecovered from aged asphalt concrete is25 dmm, how much new bitumen 70/100(Pen 85 dmm) needs to be added so thatthe final blend meets the requirements ofthe 50/70 binder?

What if you additionally used 5%rejuvenator of Penetration 800 dmm?

Source: Finnish Asphalt Specifications 2000

Mastic

Mastic is a mixture of fine mineral aggregate(<2 mm) and bitumen typically used forwaterproofing

8.10.201645

Is also considered to be theactual binder in the Stone MasticAsphalt and other Hot MixAsphalts

SMA HMA

The voids in the filler (Rigden Voids) arefilled with bitumen

8.10.201646

Makowska, Pellinen, Construction and Building Materials, 2015

The Ring and Ball Softening Point of mastic isdifferent depending on the type and amount of filler

8.10.201647

Performance:1. The stiffer the mastic the

more durable2. The stiffer the mastic the

harder asphalt is to compact

Recycling:1. The stiffer the mastic the

harder it is to separate agedgrains and re-compact

Review Questions• What is cut-back bitumen?• Where fluxed bitumen are used?• Why bitumen emulsion turns black when curing?• Why bitumen is used for waterproofing but can be foamed with

steam, why can it blend with water to form emulsion?• Why flash point is important bitumen property?• What is meant by consistency of bitumen?• What causes aging in bitumen?• Why bitumen is sticky?• What is mastic?

48

Reading Material• Course book

• Pavementinteractive.org (Internet)• http://www.eurobitume.eu/home/ (Internet)

• Shell Bitumen Handbook, Whiteoak• New Mexico Institute of Mining and Technology, ”Intro-2-

asphaltenes” (Internet)• The colloidal structure of bitumen: consequences on the rheology

and on the mechanisms of bitumen modification. Lesueur D. (reviewarticle)

49