Slurry seal andmicrosurfacing
Asphalt applications

Slurry surfacing overview
Slurry surfacing systems (slurry seal and microsurfacing) are thinemulsion cold mixed overlays which are recognized as cost-effective
restorative and preventive maintenance techniques for roadwaysof most traffic levels, airport runways and taxiways, highways,
shoulders, sidewalks, foot and cycle paths, and parking lots. They
may also be used as wearing courses on emulsion stabilized bases or
recycled roadways, bond courses, crack fill or combined with othertechniques like chipseal (“capeseal”).
The systems combine finely-graded aggregates,
bitumen emulsion, water and mineral fillers like cement
or lime. Polymers, pigments, fibers, chemical additives
and recycled materials may be included to enhance
performance or processibility, or to improve theenvironmental profile. Bitumen emulsions used in slurry
surfacing fall into the category of anionic or cationic slowset grades, but need not pass the cement mix test. The
bitumen content of the cured seals ranges from 5 to 16%
by weight of aggregate.
Slurry surfacing is normally applied on highways using
a purpose-designed self-propelled mix-paver but may
be prepared in more basic mixing equipment andapplied manually for smaller scale applications. The
slurry ingredients are dosed and mixed in the paver
then discharged into a spreader box which distributes
the material over the roadway and maintains the profileand thickness of the seal. Application rates range from
3-14 kg/m2 for a single pass. Some specially formulatedmaterials may be applied in multiple layers or in deeper
deformations or potholes. Bond coat is sometimes applied
before sealing to ensure that the new layer adheres to theexisting surface.

What can be achieved with slurry surfacing?
• Prevent water penetration• Improve skid resistance• Improve surface texture / surface drainage• Rut-filling (microsurfacing mixes only)• Correct effects of raveling• Fill small cracks including alligator cracks• Fill small potholes• Correct flushed surfaces or stripped surface dressings• Seal base courses• Wearing surface on stabilized bases

2

Two slurry products can be distinguished – slurry seal
and microsurfacing. Slurry seal is normally laid no thicker
than 1½ times the top size of the aggregate, which
can range from 3-10 mm. Mineral fillers like cement or
hydrated lime are commonly used, but are not always
required. Slurry seals waterproof and seal the surface
from water ingress and deterioration and provide a skid
resistant, smooth running surface. Typically, slurry seal canbe trafficked in 1-4 hours. “Quick-set” slurry seal can be
opened to traffic within an hour and usually has a shortermix time. Microsurfacing can be laid in multiple layers tocorrect significant deformations including rutting and issuitable for higher traffic or higher stress situations. Higher
quality aggregate is required, and usually has a top size of
5-10 mm. The emulsion must contain minimum 3 wt%
polymer by weight of bitumen and meet more demanding
durability specifications than slurry seal. It is applied with amix-paver. The mix sets within 15 to 30 minutes, and may
be trafficked within 1 hour. Mineral filler is almost always
included in the mixture. The appearance of cured slurry issimilar to that of a thin hot applied overlay but with higher
texture depth.

• Bond coat
• Delineate bus lanes, cycleways, shoulders(optionally with color)• Provide good background for road marking• Fill open graded mixes
Slurry seal and microsurfacing cannot be used to address
structural problems or major cracking associated with theexisting pavement.

Microsurfacing in Czech Republic with Redipave phosphoric acid system

Microsurfacing provides more texture than a hot mix overlay resulting
in improved wet skid resistanceSlurry surfacing mix design components

Slurry surfacing types
Application

SlurryQuick-set slurry

Microsurfacing

Emulsion type *CSS-1, SS-1

CQS-1H, QS-1

CQS-1HP, CSS-1HP

Aggregates

Wide range type I, II or III

Wide range type I, II or III

Selected, high quality type II or III

Polymer

Sometimes

Sometimes

AlwaysCement or lime

Not required

Cement, lime and / oraluminum sulfate

Uses cement or lime

Lift thickness

Thin lift only (<1.5x top size)

Thin lift only (<1.5x top size)

Thick lifts and multiple applications possible

Traffic time

1-4 hours<1 hour<1 hour

Uses

Sealing, texture improvement,
color improvement

Sealing, texture improvement,
minor re-profiling

Sealing, texture improvement, rut-fill

Other notes

Formulated for easeof-application and handwork

Strict durability requirements,
lower AC content* Other emulsion grades and different naming may be encountered

3

The history ofslurry surfacing
While cold mixes with a slurry like consistency based onclay stabilized emulsions may have been used 100 years
ago, and were further developed during the 1930s inGermany as “Schlämme”, the first slurry as we recognize
it today is believed to have been based on chemicallystabilized anionic emulsions and was in use by the late
1950s in both USA and Europe.
The beginning of the 1960s saw the development ofcontinuous mix slurry machines and systems basedon cationic emulsions, including what we would now
describe as quick-set slurry or microsurfacing. Today thevast majority of slurry surfacing uses cationic bitumen
emulsion.
We, Nouryon (then AkzoNobel) has played an importantrole in the development of slurry surfacing systems. The
Redicote Slurry System, developed around 1962, was
one of the very first cationic slurry systems and is still inwidespread use today. Around the same time Thomas
Swan & Co. Ltd. in the UK and Lancaster Chemical AZS
division in the USA developed a range of slurry andmicrosurfacing emulsifiers, later acquired by Nobel
Industries (now Nouryon) and marketed under theCatimuls tradename. The cohesion tester now used forslurry testing was developed in our Chicago laboratory. In
1985, Scanroad International (part of Kenobel Industries)bought Slurry Seal Inc. in Waco, Texas, which since 1961
had been producing Young’s slurry pavers. RaymondYoung was one of the pioneers in the manufacture ofslurry surfacing pavers and emulsion plants and was thefirst president of the ISSA (International Slurry Surfacing
Association), established in the 1960s. In the 1990s
Scanroad continued to manufacture and develop slurry
pavers (HD-10 and SR-10), emulsion plants, as well asother construction equipment in Waco, and also operated
slurry seal and micro paving contracting companies in
Europe and USA.

Slurry Seal Inc. of Waco, Texas, producers of the Young slurry seal
machines, were purchased in 1985 by Kenobel which later became
part of Nouryon

4This involvement in equipment manufacturing, emulsion
production and slurry seal and microsurfacing application
enabled us to optimize the chemical systems and todevelop expertise in emulsion production and application.
In 1994 Scanroad was renamed Akzo Nobel Asphalt
Applications Inc. (now Nouryon).
In 2001 we decided to concentrate on the supply ofchemicals to the road industry, and the equipment
manufacturing and contracting activities were divested.
Technical service laboratories were established worldwide
with full capabilities to produce emulsion on pilot scaleand do slurry mix design to support customers in theslurry surfacing market. The product range for slurry
chemicals was expanded with patented emulsions basedon phosphoric acid, and new emulsion recipes weredeveloped capable of providing quick-traffic performancewith neutral or near neutral pH emulsions.
Today we offer the widest range of slurry seal andmicrosurfacing emulsifier chemistries with products
suitable for all asphalt and aggregate qualities, including
low acid value binders and varying aggregates, and climate
conditions, including hot weather conditions and cooler
application temperatures even below 10°C.

Redicote Slurry System and Rex SlurryMatic paver circa 1965

The International Slurry Seal Association (ISSA), established in 1963
and later renamed the International Slurry Surfacing Association,
was instrumental in the development and standardization of slurry
surfacings. The first World Congress on Slurry Seal, organized by ISSA,
was held in 1977. The guidelines and test methods of ISSA form thebasis of many national standards.

Pavement preservation
Asphalt and cement concrete roads deteriorate over time throughthe action of traffic, the elements and slow chemical changes inthe binders themselves. Early deterioration as manifested by minor
cracking, ravelling, and polishing may be quickly and economically
restored by maintenance treatments.

Slurry surfacings provide a good combination of restorativeand preventive maintenance for relatively low cost, ina quick process which minimizes traffic delays, well
adapted to urban areas or night work with minimum
or no adjustment to curbs (kerbs) and drains. The seals
protect asphalt or cement structural layers from water
intrusion, improve friction and ride quality, and seal minor
cracks. Small deformations and ruts can be correctedwith slurry seals, more extensive ruts can be filled withmicrosurfacing. Slurry surfacing provides a quieter surface
than chipseal (surface dressing), with a lower texture
more receptive to road marking and less liable to snow
plough damage, and without loose rock that can lead towind-shield damage. Compared to thin or ultrathin hot
mix overlays, they generally avoid the need for extensive
milling and removal of old surfacing, do not usually require
tack coat or compaction, and provide a surface with better
wet skid resistance. The whole paving job is done withrelatively small footprint in equipment and manpower in asingle operation ideal for urban and residential locations.
Calculations have shown that polymer modified
microsurfacing is more eco-efficient than thin hot mix
overlay - it consumes less resources and emits less carbon
dioxide greenhouse gas, even excluding the benefits ofreduced traffic delays.

Bitumen emulsion is a key component of the slurry
surfacing. The finely divided bitumen particles just a few
thousandths of a millimeter in diameter can distributethemselves between and around fine aggregate particles
without the need for heat, and the nature of the emulsifiers
and fillers used means that the slurry mixes curechemically on the roadway. Polymer, in the form of latex,
can be easily incorporated either into the emulsion during
production, as is most common, or soon afterwards The
result is an environmentally friendly cold-applied product,
without the fumes of hot mix asphalt, that can quickly be
opened to traffic, often within one hour, with minimum
disruption to road users and local residents.

Pavement condition

Even earlier treatment can prevent the significant
deterioration by providing a barrier between the asphalt
structural layers and the elements. The concept ofPavement Preservation or Preventive Maintenance is now
widely accepted by highway engineers. The road shouldbe treated while still in good or fair condition when a small
investment of time and money will pay back the mostin extended life. If left too long roads become severely
damaged and are expensive and disruptive to repair orreconstruct. The Michigan Department of Transportation
reports that for every dollar spent on Preventive
Maintenance they save six to ten dollars in futurereconstruction or rehabilitation cost. In addition existing
pavements lose their skid resistance characteristics over a
period of time, and slurry seal or microsurfacing are highly
effective ways to provide an anti-skid surface.

Prevention
Rehabilitation
Reconstruction
Time / traffic

Early treatment of the road extends its life without expensive
rehabilitation or reconstruction

Energy1,00
Raw material

0,50

Emissions

0,00

Risk potential

Potential health effects

Cold mix microsurfacing
Hot mix asphalt
B70-100+polybit
Microsurfacing has a lower impact on the environment than a thin hot
mix overlay. Source: BASF

5

The paving process
The road surface is first cleaned with brushing or high pressure
wash. Thermoplastic road markings may be removed or masked,
and drains, utility covers and other areas may be masked to prevent
adherence of the slurry.

Slurry seal / microsurfacing paver
material flow diagram

Mineral filler
Water
Aggregate

Emulsion
Aggregate gate
DiverterConveyor

Mixer

Water spray bar

Spreader box

New slurry seal /microsurfacing overlay

Source: Ergon

The slurry or microsurfacing mixture is prepared in a
mobile mix paver “Slurry Paver” which holds all the
ingredients (aggregate, emulsion, water, fillers, additives
and optionally fiber and pigment). These ingredients aredelivered in the correct proportions into a helical or paddle
mixer, for example a pug mill, to produce the slurry which
is discharged into a spreader box. Generally aggregate
and cement enter the mixer first, followed by water thenemulsion. Chemical additives are injected into the water
line. The proportions of the ingredients are maintained
constant independent of the forward speed or discharge
rate of the machine, either by a common clutchshaft
driving volumetric pumps for water, emulsion, additive andthe filler feeder and aggregate conveyor or by electronic
controls. Aggregate delivery may be volumetric via anaggregate gate, or by load cells on the conveyor. Proper
calibration is vital for successful application.

6

The spreader box
The function of the box is to receive and contain the mix,
evenly distribute the material, agitate the mix to prevent
segregation, meter the material onto the road surface,control the transverse and longitudinal profile, and apply
the final texture. The box is not rigidly attached to thepaver, rather it travels along the road surface on skids,
pulled by the paving machine. These adjustable skids on
the sides and under the box support it and keep it levelto control the longitudinal profile. Augers may be used in
the box to spread the slurry across the road surface. With
some fine slurries no augers are needed, but with coarser
slurries quite intense agitation may be required to prevent
segregation and to distribute the material across the roadsurface, and the box may contain paddle type agitators aswell as the augers.

Rubber strips on the front and rear of the box, andsometimes also on the sides, help contain the mix.
Adjustable flexible or rigid strips “strike offs” across the rearof the spreader box control the thickness and transverse
profile. They can be raised or lowered at different points
across the road. The box may be split to better follow
the camber of the road. A rigid (metal) strike off is usedproduce a horizontal profile for a first “leveling course” or“scratch course”. A flexible strike off made from polymer
or rubber is used for the final course. Some pavers have asecondary strike off of softer material or burlap which canremove small drag marks and provide a consistent texture
to the final seal. The width of the spreader box maybe fixedor variable. Special V-shaped spreader boxes and strike offs
are used for deep rut-fill which are designed to produce a
profile higher in the center, to allow for compaction under
traffic.
Quality assurance and quality control
The paver has to be calibrated before use. The aggregate
may be damp which affects its bulk density and thedelivery using volumetric gate type feeders. In manycases a test strip will be laid. During construction the
consumption of materials is carefully monitored as a
double check on the metering systems. Modern pavers
have integrated data-loggers which provide a record ofmaterial consumption. The quality of ingredients may betested during construction. The slurry may be sampled
for bitumen determination and performance tests may
be performed with site materials or using the slurry
discharged from the paver.

Filler and pigments
A screw feeder is used to supply filler to the mixer. Bagsof cement or lime are usually added by hand to the filler
hopper. Some slurries can be formulated without filler, or
lime slurry has been used to avoid handling the powders.
Pigments in powder form may be added via the filler
feeder or a dedicated feeder. In some systems the pigment
is incorporated in the emulsion. Hydrated lime filler rarely
exceeds 0.5%; cement may be used up to 2.5% (expressedon aggregate).
FibersFibers are used in some high performance products toimprove wet consistency and sometimes the final strength.
They can be pre-chopped and added via a hopper or themachine may incorporate a chopper and fiber feeder.
Cellulose might be used to increase viscosity or glass or
polymer for extra durability.
Chemical additives
Chemical additives may be added to retard or (less often)
to accelerate the curing process. They are stored in a smalltank on the paver and dosed into the water line. They may
be added undiluted or as a water solution.
Handwork
It may be necessary to apply slurry by hand in order tocompletely cover irregularly shaped road areas such as
intersections and cul-de-sacs. Slurry may also be applied
from small mixing equipment and spread by hand on small
areas like cycleways and footpaths.

The fresh seal should have an even color and texture withlittle or no run off of emulsion from the sides. Workers may
correct small imperfections and drag marks in the seal
before it cures using squeegees or brooms.

Handwork

Slurry spreader box

Water
Water addition rate controls the consistency of the slurry
and may be adjusted on the paver as required.

Squeegees are most often used to distribute the slurryover the surface. In the case of quick-set slurry andmicrosurfacing, the mixture may need to be stabilized toallow enough time for handwork – which is done by theaddition of break retarders.

7Sanding
Sand may be used to avoid damage of the seal and pickup on tires if traffic is allowed onto the surface before fullcure, and especially to protect against turning or crosstraffic.
Pretreatment of the road with water or tackA spray bar on the paver can spray water onto the roadsurface before the spreader box to help wet out dust on
dry road surfaces and cool the surface. Some advanced
equipment may have an integrated emulsion distributor toapply a tack coat before the slurry, or tack may be applied
separately. Stabilized bases should be preferably treatedwith a primer seal before application of slurry.

Compaction
Rolling is not usually required but may be specified for
low trafficked areas like parking lots and airports, or for
deep rut-fill projects. Pneumatic tired rollers are used oncethe seal is stable enough to take the weight. One or twopasses are sufficient. In some cases slow moving traffic isallowed initially to accelerate the curing process.

Compaction is often specified for airport jobs

Pretreatment with tackBatch and continuous pavers
Batch pavers are used on smaller jobs and in urban areas
because they are more maneuverable. Typically theyhold about 4-8 cubic meters of aggregate and are truck
mounted. Larger batch equipment up to 10 cubic meters
may be trailer mounted. Once the material in the truck
is exhausted it must return to the stockpile and refill.
Generally the contractor will utilize two or more pavers
to provide more or less continuous paving at the job site.
Continuous run pavers can be refilled by nurse trucks
without stopping and are used on larger jobs. Compact
continuous machines suitable for urban work are available
and batch pavers can be retro-fitted with special nurse
feeders for continuous operation.

8

Sweeping
All of the aggregate is incorporated into the surfacing andsweeping of the finished seal is not normally required, but
may be specified for airport jobs or in response to earlyraveling of the seal.
Multiple layers
In microsurfacing a “scratch course” (correction or levelling
layer) may be applied and allowed to cure under traffic
before placement of the wearing course. Usually 12 hours
or more is used between applications. The scratch courseshould be swept before covering to avoid drag marks.
Fog seal
A fog seal may be applied to prevent early raveling in cold
weather paving.

The curing process
Mixing the slurry components initiates a chemical process whichleads to the curing of the seal. The process can be considered in fourstages.

Mix time
Set time
Traffic time (cohesion)

Mix time
During this period the slurry is brown, fluid andhomogeneous and can be mixed. The slurry must remain
workable and flowable during mixing and in the spreader
box so it distributes easily over the road surface and the
profile can be controlled with the strikeoffs
Set time
As the chemical reaction proceeds, the slurry builds
viscosity, sometimes very rapidly and can no longer bemixed. Clean water separates from the bitumen andaggregate fractions. The process is irreversible but the seal
is not strong enough to support traffic.
Traffic time
The slurry builds sufficient cohesion that controlled speed
traffic can be allowed on. The color is dark brown or black.
Full cure
Trafficking and time complete the curing process and theseal has the character of a hot mix overlay.

Additive tank on the paver
Additive is used to extend the mix time in hot weather

Mix time and temperature
The mix time must be sufficient to allow the slurry to passthrough the mixer and spreader box without problem. The
residence time in the mixer is short only 10-15 seconds
and 45 seconds or less in the spreader box would be
typical. Different machines and boxes may require different
minimum mix times. Too short mix time leads to “breaking
in the box” which can completely stop production or leadto a build up of hard mix in the corners of the box causingdrag marks on the seal when it leaves. Hand work requires
longer mix time.
The chemical reaction in the slurry is accelerated byheat. Hot weather or hot emulsion can lead to premature
breaking and insufficient mix time. This can be correctedby the addition of chemical additives “dopes” or“breakretarders” which are added to the water and act todeactivate the aggregate. On the other hand the reactionin the slurry is slower in cold weather. The reaction incold weather can be helped by the use of hot emulsion.
With some materials, mix time and set time respond to
filler content. Otherwise the emulsion recipe needs to bemodified for cold weather paving.
One should be careful about the amount of break-retarderused in the mix; it is not good to use an excessive amount.
It is best to test the slurry mixes with the expected amountof break-retarders used in the field to ensure that they are
not significantly altering the performance properties of thebinder and the slurry seal or microsurfacing mix.

Fresh slurry is brown but cures to a black surface with an appearance
similar to hot mix asphalt. Source: Duncor

9The chemistry of
the curing process
The reaction of bitumen emulsion with aggregate incold mix processes has been extensively studied. The
mechanism of the setting and curing process depends on
the interaction of the emulsion and the other componentsof the seal.
The droplets in bitumen emulsions are charged – positivein cationic emulsions or negative in anionic - and thischarge is responsible for the stability of the emulsion. The
charge is sensitive to pH – for example some cationicemulsifiers lose their charge at high pH. Moreover bitumen
contains natural acid components which may develop
negative charge at high pH. In quick-set slurry systems
and microsurfacing the ingredients are designed to react.
Most often alkaline fillers like cement or lime are included
to produce a large rise in pH, and to generate soluble
calcium ions.
Slow-setting systems
Even without a chemical reaction between the emulsion
and the aggregate and filler components, the seal will still
cure slowly simply due to the evaporation of water in asimilar manner to the drying of latex paint. As water leaves
the system the droplets of bitumen and aggregate areforced closer and closer together and the concentrationof soluble ions in the system also rises. The consequence
is destabilization and coalescence of the emulsion, andsticking of the aggregate particles together. In practice
it is hardly possible to have a system where there is no
chemical interaction between the bitumen droplets andthe aggregate or filler fraction.
Anionic quick-set systems
In anionic quick-set systems containing resin orsulphonate emulsifiers, cement is used to produce ahigh concentration of calcium ions which destabilizes
the emulsion by neutralizing the negative charge on theemulsion droplets. The insoluble calcium soaps formedin the process are not effective emulsifiers and the system
breaks rapidly.
The Redicote slurry system
The Redicote slurry system is based on cationic slow
set emulsion stabilized with quaternary ammonium
emulsifiers (Redicote E-11). The emulsion droplets havea positive charge and are relatively insensitive to pHchanges. When mixed with fine aggregate these droplets
bind closely with negatively charged mineral particles
forming tightly bound assemblies which provide structure10

to the seal. The attraction between the bitumen and theaggregate is strong enough to squeeze water out of thesystem creating a high viscosity, cohesive mat of cold mix.
Eventually water is displaced from between the particles
and evaporates leading to full curing. The emulsions
typically pass the cement mix test, and in these systems
cement and lime typically extend the mix time because
the soluble ions they produce can reduce the interaction
between the bitumen droplets and mineral particles.
Cationic quick-set and microsurfacing systems
Developed in the 1960s, these systems use lime or
cement filler in the mix and emulsifiers which require
acid formulations to be cationic. The emulsifiers used
are characterized by large head groups with multiple
charged centers. When the slurry components are mixed
the cement reacts with the acid. The acid is neutralized,
the pH rises rapidly, and at the same time large quantities
of soluble calcium ions are produced, and the charge on
the emulsifiers is largely destroyed. The acid components
in the bitumen can play an important role in the breaking
process. At the high pH and calcium ion concentrations inthe slurry the droplets of bitumen rapidly coalesce.
Phosphoric acid system
Phosphoric acid slurry systems were developed inGermany during the 1970s. The emulsions are formulatedwith phosphoric acid rather than hydrochloric. Phosphoricacid forms insoluble salts with calcium which limits or
buffers the pH changes which occur in the slurry and thelimits the concentration of calcium ions. The pH of theslurry never exceeds 9 and the charge on the emulsion
droplets is maintained. Destabilization and setting arethought to occur though interaction of the bitumen
droplets and oppositely charged mineral and filler particles.
Because the filler particles are negatively charged at theslurry pH, they directly contribute to the breaking process.

Counter-ion

Bitumen droplets in emulsion have charge, which is destroyed in the
breaking processMix design
A wide variety of materials can be slurried successfully, suitable fora range of applications from footpaths and parking lots to interstate
highways.
To ensure the function and durability of the surfacings,
the materials and the combination of materials need to becarefully evaluated with a view to the intended application.
The design process involves preparing slurry on a small
scale in the laboratory and testing its properties. It focuseson the quality of the materials used, their proportionsin the slurry, their compatibility, and the durability of the
final seal. The output of the mix design process is a target
mix recipe comprising quality raw materials, which canbe processed through the mix and lay down equipment
under the expected environmental conditions, and inproportions designed to provide a durable surfacing,suitable for the intended application.
The most widely adopted design process is that developedby the ISSA and also described in the standards of manynational and local authorities. Separate guidelines aredescribed for slurry surfacing and microsurfacing. The
Performance Guidelines and Technical bulletins of
ISSA describe recommended specifications for the raw
materials, test methods to determine the compatibility
and processibility of the components, and performance
tests which evaluate the final properties of the cured seal
and the speed at which the seal can be opened to traffic.
The guidelines and test methods are under continual
development and review. The main outputs of the mix
design process is the minimum and maximum asphalt
content of the mixture, the filler content, the rangeof water content and whether the mixture meets therequirements of a quick-traffic system. The design may
also include an evaluation of suitable chemical dopes, andthe sensitivity of the design mix to temperature.
Laboratory mix-design with representative materials
from the field that takes into account the reactivityof the aggregates and field application conditions,especially temperature, is a key step preceding the slurry/
microsurfacing project. The emulsion reactivity is adjusted
by the type of emulsifier/emulsifiers, dosage and pH of
the emulsion to match the reactivity of the aggregatesand field conditions. In addition consistent quality of the
raw materials, especially the aggregate, calibrated paving
equipment and a thoroughly trained crew are importantfactors to complete a successful slurry/microsurfacing
project. These factors become more important for a quick
traffic slurry/micro project.

Aggregate gradations
Sieve size

Typ I
% passing

Typ II% passing

Typ III% passing

100

100

100

3/8

(9.5 mm)#4(4.75 mm)100

90-10070-90#8(2.36 mm)90-100

65-90

45-70

#16

(1.18 mm)

65-90

45-70

28-50

#30

(600 um)

40-60

30-50

19-34

#50

(330 um)

25-42

18-30

21-25

#100

(150 um)

15-30

10-21

7-18

#200

(75 um)

10-20

5-15

5-15

Aggregate gradations recommended by ISSA. Mixes often contain filler(cement or lime) which should be considered part of the gradation.
Gap graded materials have been used successfully.

Aggregate
While a wide range of aggregate gradations can be
successfully adapted for use in slurry surfacing, many
local and national authorities have adopted the gradations
developed by the ISSA and designated by the descriptors
type I, type II and type III (see table above) which arecontinuously graded with top sizes in the range
3-12.5 mm. Additional requirements for abrasion
resistance, freeze thaw resistance may be required.
Fully crushed aggregate is usually specified. It is possible
to use blends of different aggregates to achieve gradationand durability requirements. The reactivity of the aggregate
towards emulsion is largely determined by the very finest
components which have the highest surface area.
Clays are reactive in the slurry system and moreover havea negative effect on durability. Sand Equivalence (SE) is
used to control the clay content – the higher the SE the“cleaner” the aggregate. Typically a minimum 45 is required
for slurry and 65 for microsurfacing but lower numbers
might be accepted based on experience and availabilityof local materials. Titration of the aggregate fines with asolution of the cationic dye methylene blue can provide a
useful indication of reactivity towards cationic emulsions.

11

Emulsion
The emulsions typically meet the local specifications forcationic or anionic slowsetting grades, but do not needto meet the cement mix test requirements. Some regions
specify a “quick-set” grade of emulsion for quick-trafficslurry systems. Polymer is often included – in the form oflatex or polymer modified binder. The properties of theresidue depend on the application and region. Minimum
softening point, elastic recovery or Multiple Stress Creep
Recovery (MSCR) results may be specified in some regions
to minimize flushing and rutting in hot weather.
Fillers
The source and type of filler can influence the slurry
properties and the mix design should be done with the job
materials whenever possible.

Compatibility by the Shultze Breuer Ruck (S-B-R) test
Long term moisture damage in microsurfacing may berelated to the compatibility of the mastic components.
In the S-B-R test a fixed gradation of the finest portionof the aggregate and filler is mixed with emulsion,
cured and compacted into “pills” which are subjected tosoaking in water, abrasion and a boiling stripping test. The
performance is scored on a points system. Because theamount of bitumen in the test sample is fixed, the results
are sensitive to the filler content and typically set an upper
limit on the filler content of the slurry. The test identifies
emulsion chemistry incompatible with the finest mineral
fraction.

Water
Clean water is required. Potable water is suitable.
Other ingredients
Other intended ingredients such as fibers, pigments, andchemical additives need to be included during the mix
design process.
Mix time
Simple hand mixes with small quantities of materials
are used to check the mix time of the materials, theconsistency (fluidity) of the mixture and how these areaffected by filler content and dope. Mixes with a range ofcompositions will be tested. Mix design specialists are able
to predict how a slurry will behave in the field on the basisof these small scale tests. If necessary the emulsion canbe reformulated in order to provide the required mix time.
The mix tests may be repeated at higher temperatures toensure that the mix time can be achieved in hot weather.

In the Schlulze Breuer Ruck test small “pills” prepared from the slurry
ingredients in fixed proportions are subjected to water soak andabrasion, eventually in boiling water, and the damage assessed on apoints scale

Cohesion development by cohesiometer
The hand mixtures are poured out and the rate ofcohesion developement measured using a cohesiometer.
Standards have been set to identify quick-set and quicktraffic systems. To ensure good hot or cold weather
performance the test can be done in a temperature
controlled room or the materials can be conditioned in anoven or refrigerator.
Durability by wet track abrasion tester (WTAT)
Seals, fully cured at 60°C, are immersed in water for
1 hour or 6 days and then subjected to 5 minute abrasion
with a weighted rubber hose under water to simulate
the effect of traffic in wet conditions. In most regions thetests are done using just the minus 4 mesh portion of theaggregate. The weight loss is compared to specification
limits. Increasing the bitumen content usually reduces theweight loss and the WTAT sets a minimum value for thebitumen content.

12

Too much binder leads to deformation in asphalt mixes. Curedsamples of microsurfacing are prepared 1.25x thicker than normal
and subjected to 1000 cycles in the LWT. The increase in width ismeasured. The test sets an upper limit on the bitumen content of
micro-surfacing when it is to be used in thick or multiple lifts.

Determining maximum bitumen content byloaded wheel test (LWT)High levels of bitumen may result in flushing anddeformation which are addressed in the LWT. The LWT
results set a maximum limit on the bitumen content. The
combination of the LWT and WTAT test results leads to an
acceptable range of bitumen contents.

Other tests and design approaches
Not all the standard tests and specifications described by
ISSA are demanded in all regions, and some of the tests
may be modified according to the requirements of thelocal markets and applications.
Mix design specialists often use simple tests like blot test
(which shows the initial set time when clean water isexpressed) to determine the progress of the reaction.
In some countries the WTAT test has been modified(Surface Cohesion Test) to study early cohesion
development. Seals are cured at room temperature (orexpected job site temperature) and subjected to abrasion
with a wheeled attachment to the WTAT. The weight loss isused to determine the traffic time.
Instead of the LWT, optimum or maximum bitumen
content can be calculated from the surface area of theaggregate, or determined by Marshall or modified Marshalldesign methods.

Abrasion loss

Statedlimit(75g/SF)

Asphalt content
A. Minimun asphalt content by
wet track abrasion test

Sand adhesion

Statedlimit(50-75g/SF)

Asphalt content
S. Maximum asphalt content byloaded whel test

LWT curve

Sand adhesion

Statedlimit

WTAT curve
Allowable AC range
Tolerance range (3%)
Median tolerance range =optimum asphalt content ( +_1.5%)

In the cohesion test small samples are mixed and are cast into molds,
which are then removed. The cohesion tester measures the torquerequired to tear apart a specimen with a rubber foot loaded to 29 psi,
designed to represent the effect of power steering on the surface.
Measurements taken over a period to determine the set and traffic time.

The minimum bitumen content is determined by the WTAT andthe maximum by the LWT (either sand adhesion for flushing or
deformation for rut-fill).
Together they set a range for the bitumen content of the seal.

13

Tips for meeting
mix design specifications
Too little mix time
• Increase emulsifier dosage• Formulate at higher soap pH (cationic systems)• Use chemical break retarder (dope) or aluminum
sulphate• Use lime filler instead of cement• Use different emulsifier chemistry• Increase filler content (some systems)

Fail wet track abrasion test
• Increase emulsion content• Increase cement or lime content (most systems)• Increase polymer content• Change polymer type
• Formulate to higher soap pH (cationic grades)• Use different emulsifier chemistry• Include an acid dope for the bitumen or soap phase

Too slow cohesion development• Reduce emulsifier content if there is sufficient mix time
• Increase filler content (some systems)• Formulate at lower soap pH• Reduce or eliminate break retarder if sufficient mix time
• Include solvent in recipe, if allowed, to improve lowtemperature cohesion development• Include an acid dope for the bitumen or soap phase• Use different emulsifier chemistry• Use phosphoric acid system and appropriate emulsifier
chemistry

Fail sand adhesion test
• Reduce emulsion content• Raise filler content

Fail loaded wheel test (rutting)• Reduce emulsion content• Formulate at lower soap pH• Increase filler content

Fail Schulze Breuer Ruck
• Reduce filler content• Increase polymer content or change polymer type• Raise or lower emulsifier content (depends on system)• Change emulsifier chemistry
Fail consistency• Adjust water content• Adjust filler content• Select alternative break retarder

ISSA specifications
Tests

MethodSlurry seal

Microsurfacing

Mix time, sec. (25°C)

TB113

80 min

120 minCone consistency

TB106

2-3 cm

Wet cohesion- 30 min- 1 hr

TB100

For quick traffic only
12 kg-cm, min
20 kg-cm, min

20 kg-cm, min

Wet stripping

TB114

90% min

90% min

WTAT, g/m loss
- 1 hour soak
- 6 days soak

TB100
807 maxNone

538 g/m2, max
538 g/m2, max

LWT
Lateral displacement
Specific gravity after 1000 cycles

TB147

LWT
Excess asphalt sand adhesion

TB109

Classification compatibility (Schultze Breuer Ruck)

TB144

2

14

5%, max
2.1 maxHigh traffic areas only
538 g/m2, max

538 g/m2, max
11 points, minOur mix designlaboratories
We provide slurry mix designs to its customers all over the worldin fully equipped laboratories. Conveniently located for shipmentof samples and with good knowledge of local requirements, thelaboratories are able to develop emulsion recipes to match theneeds of local materials.
Bridgewater

Itupeva

Stenungsund

MumbaiShanghaiSingapore

15

Overview of our products
Product overview
ConventionalslurryQuick-trafficslurryMicrosurfacing

Produce “super-stable” cationic slow set emulsions
for the most reactive aggregates and hot conditions

Yes

No

No

Produce cationic slow setting emulsions withexcellent latex compatibility. Cement or lime filler notalways required. Emulsions can be formulated withneutral or near neutral pH. The products can also be
used as dope in these systems.

Yes

Sometimes

Yes

Produce cationic emulsions for quick-traffic systems
and microsurfacing. Choice of product determines
mix time. Products can be combined to achieve
reactivity suited to most aggregate types and climate
conditions. Latex modified or polymer modified
asphalt can be used. The products can also be used
as dopes in these systems.

Yes

Yes

Yes

Products for phosphoric acid systems. Provides
reliable cohesion development with wide range ofbitumen including low acid bitumen. It is a premium
system for nigh work, early or late season cooler
weather paving.

Yes

Yes

Yes

Can be used for both anionic and cationic quick-set
recipes. Excellent latex compatibility.
Can be formulated together with Redicote E-11,
Redicote C-450 or Redicote C-471 to produce
cationic quick-set emulsions with a wide range ofreactivity.

Yes

Yes

Yes

Product

RegionComments

Redicote E-4868

A

Redicote E-4875

E, S, C

Redicote E-11

E, S, C

Redicote E-11E

A

Redicote E-11HF

E

Redicote E-11HF-1

A

Redicote 611

E, S

Redicote 404

E, S, C

Redicote C-450

A

Redicote C-471

A

Redicote C-500

E, S, C

Redicote C-320

A

Redicote C-320E

E

Redicote EM-44

E

Redicote EM-44A

A

Redicote E-7000

A, E, SA = North and South America, E = Europe, Middle East, Africa, S = South Asia, C = China
Products may not be available in every country within a region

Additives
Generally the emulsifier can also be used as a breakretarder on the slurry paver.
Water soluble
Redicote E-11HF-1, Redicote E-11HF, Redicote 611,
Redicote E-7000 and Redicote C-450 are particularly
suitable because they are water soluble and do notcontain flammable solvents.
Cohesion development
Redicote E-62 can be added into the bitumen or
postadded into emulsions to improve cohesion
development and durability.

16

Options forconventional slurry
The Redicote slurry system

Super-stable emulsions for hot climates

Developed more than 60 years ago and still going strong,
the Redicote slurry system has passed the test of time withhonors.

The hot climates and highly reactive aggregates
experienced in some geographical regions can challenge
conventional cationic slurry emulsions. Speciallyformulated “super-stable” emulsions have been developed
to provide mix time in these demanding conditions.
Nouryon offers Redicote E-4868 and Redicote E-4875
which are concentrated liquid emulsifiers able to produce
superstable cationic slow-setting emulsions at dosagesof 0.8-2.0%. The emulsions pass the cement mix test
and show excellent storage stability. The system provides
a slurry with traffic times in the 2-4 hour range underlaboratory conditions, but often faster in the field becauseof the hot climates where it is used. The slurry seals do notmeet quick traffic requirements.

Today products in the Redicote E-11 family are produced
worldwide in Singapore, Brazil Sweden and USA. Why is
the system still so popular? It is a simple, reliable and value
for money process which performs well in a wide range ofclimates.
Neutral pH emulsions with strong cationic character
Neutral pH emulsions with strong cationic character The
Redicote E-11 family of quaternary ammonium emulsifiers
are low viscosity, completely water soluble and emulsions
can be formulated without the need for acid, althoughhydrochloric acid and/or calcium chloride may beincorporated if desired. The built-in cationic charge on theemulsifier molecules produces emulsion with exceptional
adhesion to siliceous aggregates, while typically passing
the cement mix test and particle charge tests.
Hand work
The creamy nature of the slurries make them ideal for
handwork with low risk of segregation. Products preparedusing Redicote slurry system can be applied by hand forthe maintenance of footpaths and cycleways.
Blacker seals
Because the emulsions are neutral, with little or no acidused, less cement, lime or limestone aggregates are
dissolved which avoids unsightly white surface staining
caused by soluble calcium salts.
Latex
The emulsions are particularly compatible with latex.
With the right order of addition natural rubber and someanionic SBR latex grades can be incorporated into the soap
solution, or can be stabilized in a separate production step.
Break control additive
The Redicote E-11 is its own control additive. Emulsions
can be prepared with the minimum of chemical and themix time adapted on the paver by addition of
Redicote E-11. High flash point grades of the product areavailable for safe use in the field.

Cement and lime
Some aggregates with very high natural filler content
may provide good slurry consistency without cement but
normally a high level of cement (0.5-2%) is recommended
to provide the right slurry consistency and to ensure
durability of the seal. Hydrated lime may substitutefor cement to provide additional mix time with someaggregates. Mix time and cohesion development are notvery sensitive to filler content but generally increasing filler
content increases the mix time while reducing the time
before the road can be opened to traffic.
Mix time
Increasing the emulsifier dosage increases the mix time.
Break retarders are not used.
Emulsion pH
The products are completely soluble in water without
the need for acid.The performance is relatively insensitive
to pH. A soap pH of 2-3 is typical. Phosphoric acid orsulphuric acid can be used instead of hydrochloric,
depending on local availability, but the compatibility ofthese acids with the particular emulsifier needs to beverified.
Polymer
The systems are not normally modified. Polymer modified
binders can be used. The Redicote E-4868 andRedicote E-4875 products are compatible with natural
rubber latex but can show reduced mix time with SBR latex.

17

Quick-set slurry andmicrosurfacing withtraditional hydrochloric
acid system
Redicote emulsifiers for the traditional slurry systems based onhydrochloric acid are fatty alkylimidazolines manufactured in Europe andthe USA, derived from our own polyethylene amine raw materials.
Products provide a range of emulsion reactivity
The key to successful quick-set slurry and microsurfacing
is to closely match the emulsion reactivity with thereactivity of the aggregate, under the local environmental
conditions. The more reactive the aggregate and thehotter the local conditions, then the less reactive shouldbe the emulsion in order to provide sufficient mix time.
The products Redicote 404, Redicote C-471,
Redicote C-450, and Redicote C-500 are evolved fromthe original Catimuls emulsifiers introduced in the 1960s.
While all the Redicote products used in the traditional
microsurfacing systems share similar chemistry and areused in the same way, differences in the details of theirchemical structure provide emulsions with different
reactivity.
By the choice of emulsifier, or by combining more than
one emulsifier, the emulsion formulator can match theemulsion reactivity with the available aggregates andclimate conditions without the need for extreme highor low chemical loadings which might impact emulsion
quality or performance.
All the Redicote products mentioned below meet therequirements of both microsurfacing and the lower
technical demands of quick-set systems.
Redicote C-471 produces the most reactive emulsions,suitable for the least reactive aggregates. Redicote C-500
and Redicote C-450 product the least reactive emulsions
suitable for the most reactive aggregates. Used alone
or in combination the products allow the full range of
microsurfacing aggregates to be used.

18

Redicote 404 provides a medium reactivity emulsion andis often the best choice where only a single emulsifiersystem is desired.
Typical use levels for the products range from 0.6-1.8%,
basis emulsion. Some contractors favor a process using
very reactive emulsion recipes with low dosages of
emulsifier, and use additional chemical on the paver“break retarder” to adapt the breaking characteristics.
Others prefer not to use any chemical in the field, and theemulsion recipe will reflect these approaches.
Emulsion pH
With all the products in this class, cohesion developmentin the slurry is generally helped by low emulsion pH,
although at the expense of some mix time. For the very
fastest cohesion development a soap pH as low as 1
may be required, but for many systems a soap pH of 2
is sufficient to meet all the requirements for quick-trafficsystems.
Bitumen quality
The system demands bitumens with some acid value,
preferably 0.4 mg KOH/g or higher, to function correctly.
As natural bitumens with this acid value become lessavailable, dopes such as naphthenic or fatty acids canbe added to the bitumen before emulsification to help
cohesion development and durability of the seal.

Polymer
Natural or synthetic rubber latex is the most common
modifier. Cationic grades of latex are compatible with thefinished emulsion or can be injected into the soap. Anionic
grades of latex can sometimes be incorporated into thesoap in a batch process before acid addition but somestabilization (e.g. with Redicote E-11) may be required.
Break control additive
Redicote C-450 is water-soluble and is the preferred breakcontrol additive for the systems. Redicote C-471,
Redicote 404 and Redicote C-500 can all be used as
dope, but are less easily soluble in water. They form stabledispersions, or can be partially neutralized with acid toprovide full solubility. Redicote 611 is a low viscosity fullywater soluble product widely used to control mix time inEurope.

Cement, lime and aluminum sulphate
Cement is the most common filler for microsurfacing
systems based on hydrochloric acid. Hydrated lime may
be used with some highly reactive aggregates to provide
more mix time. The filler is an essential part of the system
and may vary between 0.25 and 1%, or even higher. The
effect of filler on mix time is highly variable. In most cases
the filler extends mix time.
Aluminum sulphate is used in western areas of the UnitedStates in so- called quick-set, quick-traffic systems,
which provide many of the features of microsurfacing
but to less demanding specifications. Occasionallyaluminum sulphate is used in microsurfacing but always
in conjunction with cement. The emulsifiers mentioned inthis section are fully compatible with aluminum sulphate.
Aluminum sulphate has the effect of extending mix time.

19

The Redipave slurrysystemConventional slurry systems use hydrochloric acid to formulate theemulsions. The Redipave system uses phosphoric acid together withpatented emulsifiers in emulsions for quick-set, quick-traffic slurry andmicrosurfacing systems which perform well with a wide range of bitumens,
including low acid bitumen. Polymer modified binders as well as latex
modified emulsions can be used.
Bitumen quality
High acid value binders traditionally derived from
Venezuelan crude oil have been the basis of the mosteffective slurry and microsurfacing systems. As crude
sources and refining processes change, it can be difficult
to maintain performance with today’s bitumens, evenwith the use of acid dopes and other additives. A majoradvantage of the Redipave system is that it can use a wide
range of binders including low acid value bitumens andsynthetic bitumens derived from petroleum resins.
Blacker seals
After curing the seals prepared using the Redipave system
are clearly blacker than those made with the conventional
systems, an effect resulting from the way the emulsioninteracts with cement in the slurry.
Cool weather paving and night work
The phosphoric acid systems show exceptionally rapid
cohesion development, good even at low temperatures,making them especially suitable for cool weather andnight work.
Emulsion formulation
Easy to use, liquid emulsifiers Redicote EM44 andRedicote C-320 are recommended.
Technical grades of phosphoric acid are suitable. The
target soap pH is in the range 2.5-3.5 and 0.6-1.5%
emulsifier is sufficient for most aggregates.
Polymer modified binders may be used. Alternatively,
cationic polymer latex can be incorporated into the soap
solution or into the finished emulsion. Some anionic latex
grades can be incorporated into the soap solutions, but
additional stabilization may be required.

20

The slurry
The slurry comprises emulsion, fine grained aggregate,
filler and water. Portland cement filler is an essential
component of the Redipave system – hydrated lime is
not suitable. Water is used to adjust the consistency of the
mixture – typically a little less water is used in the systemthan in conventional hydrochloric acid systems.
The chemistry of the system is different and someaggregates which react poorly in the hydrochloric system
can give good performance with phosphoric acid.
Mix design
Mix design with the Redipave system is undertaken in thenormal way. The emulsion recipe and slurry compositionis adapted for the reactivity of aggregate and the climate
conditions and the desired cohesion development using
hand mixes and the ISSA cohesiometer. The proportion ofbitumen in the slurry is determined by durability tests likethe Wet Track Abrasion test.
Increasing emulsifier content in the emulsion provides
more mix time. The mix time is less temperaturesensitive than in the hydrochloric acid system. The mix
time is typically reduced by increasing cement content
and cement dosage can be used in the field to adjust
mix reactivity. Mixtures with good consistency are
produced with cement levels as low as 0.25%. Aluminum
sulphate can be used together with cement to provide
extended mix times without any negative effect on slurry
consistency or cohesion development.
Chemical break retarders like Redicote E-11 HF-1 orRedicote C-450 can be used on the paver to extend mix
time if necessary. If chemical break retarders are to be
used, we always advise that they are evaluated during themix design process.

When to use Redipave?
• When conventional systems will not build cohesion• For night work and cool conditions• With difficult binders including polymer modified
bitumens and synthetic binders• To avoid corrosion issues during manufacture, storage
and paving• When hydrochloric acid is not readily available or use isrestricted

21

Systems using
Redicote E-7000
Our patented Redicote E-7000 betaine emulsifier allows the emulsion
formulator to meet the requirements of quick-traffic slurry systems but
using emulsions of neutral or near neutral pH and providing excellent
value for money.
Easy to use
Redicote E-7000 is a completely water-soluble low
viscosity liquid emulsifier which can be used to prepare
both cationic and anionic emulsions for slurry surfacing,and is compatible with all emulsifier types. Used alone
or in combination with emulsifiers such as Redicote E-11
or Redicote C-450, it can produce cationic emulsions
which produce slurry meeting quick-set, quick-traffic
requirements. Emulsions typically pass the cement mix
test, yet the slurries build cohesion faster than recipes
based on super-stable emulsions.
Latex compatibility
Alone, or combined with Redicote E-11, Redicote E-7000
provides excellent latex compatibility as well as plenty ofmix time in hot conditions or with reactive aggregate.
Bitumen quality
High acid value bitumens provide better cohesion
development. Additives can be used to help cohesion
development in cases where high acid value bitumens are
not available.
Emulsion pH
The emulsions can be produced over a wide range ofpH from 2 to neutral, avoiding the corrosion problems
seen with traditional microsurfacing systems. As labelingand placarding requirements of emulsions become more
restrictive, the ability to formulate effective emulsions at
pH close to neutral is an advantage.
Compared to conventional recipes the emulsions withco-emulsifiers are neutral or near neutral with soap pH
in the range 4-7. A typical recipe might use 1-2%
Redicote E-7000 and 0.4-0.8% of the co-emulsifier. Whenused alone we recommend a soap pH of around 2.
Overall the formulations provide significant cost savings
compared to other quick-set slurry recipes, and becauseof the lower acid content of the emulsions, white staining
due to soluble calcium ions is reduced.

22

Anionic slurries
For anionic quick-set emulsions, typical recipes use
1.5%-2.5% emulsifier with a soap pH of 11.5. These
emulsions can optionally be latex-modified. Cement
should be included in the mix design as it is necessary toattain quickset, quick-traffic properties with this system.
With highly reactive aggregates, Redicote E-7000 can be
combined with Redicote E-6945.
Break control additive
Redicote E-7000 is water-soluble and is the preferred
break control additive for both anionic and cationicsystems. Redicote E-11 or Redicote C-450 are effective at
extending mix time in cationic systems.

Troubleshooting
slurry paving
ProblemPossible cause

Possible solution

Premature break in mixer
or spreader box

Hot emulsion
High clay or fines in aggregate
Insufficient emulsion or water
Hot road surface
Aggregate segregation in stockpile
Too long residence time
Too reactive emulsion
Cold conditions
Overdosage of additive
Overdosage of emulsion
Low aggregate reactivity
False slurry/false break
Change in bitumen source
Emulsion not reactive enoughToo little fines, incorrect grading
Too much emulsion or water
Filler feeder problem
Aggregate dry and segregating
Underlying surface variable in composition
Mix too dry or too “fast” to self-leve
Varying emulsion or water content l
Poor start and stop procedures on paver
Opened to traffic too early
Very hot road temperatures
Power steering damage in parking areas
Cold or freezing conditions
Opened to traffic too earlySegregation
Poor embedment of coarser particles
Seal applied too thinly
Aggregate gradation too coarse
Poor aggregate interlock
Secondary strike off dislodging coarse stone
Slow cure, low paving temperature
Too high water content
High filler content
Poor emulsion quality
Road surface not clean
Road surface not wetted
Road surface polished
Too high emulsion content
Underlying road surface soft or rich
Too low filler or fines in mix
Raveling of coarse aggregate
Too high application rate
Too much water in mix
Extremely hot road temperatures
Oversize in aggregate
Spreader box or strike offs not clean
Inattentive corrective actions
Slurry applied too thinly (less than topsize)
Variable height underlying surface
Incomplete sweeping
Too fast road speed for paver
Too dry or too “fast” mix for self-levelling

Check temperature, use additive, allow to cool
Check grading and methylene blue value, use additive
Check calibration on paver
Spray water. Pave in early morning
Remix stockpile
Reduce residence time by increasing road speed
Re-formulate emulsion e.g. increase emulsifier
Reformulate emulsion, use warm emulsion
Reduce or eliminate additive
Calibrate flows on paver
Check gradation, methylene blue value. Increase filler
Treat as premature break – “slow down” the mix
Repeat mix design
Reformulate e.g. lower emulsifier content or lower pH
Increase filler (cement) content. Check gradation
Calibrate flows. Use drier mix. Check aggregate moisture
Check filler dosing system
Check moisture content, gradation of stockpile and calibration
Use leveling or scratch course
Use wetter or slower mix
Check calibration
Improve process
Sand the seal where traffic vehicles turns or crosses
Sand the seal where traffic turns or crosses
Consider compaction to accelerate final cure
Avoid paving in cold conditions, reformulate emulsion
Control traffic speed for extended period
Increase filler content. Check aggregate gradation
Consider compaction or fog seal
Should be 1.25x largest aggregate
Check gradation
Check crushed faces on coarser particles
Adjust strike off to prevent damage
Adjust system reactivity. Use warm emulsion
Use drier mix
Formulate with lower filler content
Check particle size
Better preparation
Spray water or tack. Increase fluids content of slurry
Use leveling or scratch course
Check mix design
Consider capeseal
Check gradation and mix design
See early raveling above
Should be <1.5x top size for slurry
Use drier mix
Consider sanding problem areas
Screen aggregate
Keep box clean. Avoid broken material in box
Increase application rate
Use leveling or scratch course
Improve sweeping
Slow down
Slow down
Use wetter or slower mix (e.g. add additive)

Extended set and traffic
time (slow cure)

Emulsion or slurry running
off the mix
Varying color or texture

Tire marks in freshly paved
seal
Early raveling(loss of coarse aggregate)

White or grey staining
on seal surface or
pronounced brown orgrey color to seal
Delamination of seal

Early fatting up of binder inwheel paths

Drag marks

Washboarding or ripple
effect23

Nouryon is a global, specialty chemicals leader.
Markets and consumers worldwide rely on our
essential solutions to manufacture everyday
products, such as personal care, cleaning
goods, paints and coatings, agriculture andfood, pharmaceuticals, and building products.
Furthermore, the dedication of more than 7,900
employees with a shared commitment to ourcustomers, business growth, safety, sustainability
and innovation has resulted in a consistently
strong financial performance. We operate in over
80 countries around the world with a portfolio
of industry-leading brands. Visit our website andfollow us @Nouryon and on LinkedIn.

All information concerning our products and/or all
suggestions for handling and use contained herein(including formulation and toxicity information) are
offered in good faith and are believed to be reliable.
However, Nouryon makes no warranty express or
implied (i) as to the accuracy or sufficiency of suchinformation and/or suggestions, (ii) as to any product’s
merchantability or fitness for a particular use or (iii) thatany suggested use (including use in any formulation)
will not infringe any patent. Nothing contained hereinshall be construed as granting or extending any licenseunder any patent. The user must determine for itself
by preliminary tests or otherwise the suitability of any
product and of any information contained herein(including but not limited to formulation and toxicity
information) for the user’s purpose. The safety of any
formulations described herein has not been established.
The suitability and safety of a formulation should be
confirmed in all respects by the user prior to use. The
information contained herein supersedes all previously
issued bulletins on the subject matter covered.
Products mentioned are trademarks of Nouryon
and registered in many countries.

nouryon.com

June 2022

Contact us directly for detailed productinformation and sample request
website | nouryon.com/markets/asphalt
email | asphalt@nouryon.com