SLURRY SEAL PROJECTS

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SLURRY SEAL PROJECTS

• By Richard Sampson
• Dustin Lang

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WHAT IS A SLURRY SEAL?

• A Slurry Seal is a cold mixed asphalt. It
  consists of a graded aggregate, a binder, fines
  and additives. It is a hard wearing surfacing for
  pavement preservation.

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WHAT IS A SLURRY SEAL MADE CONSIST OF

• Mixture of
• Asphalt Emulsion (Approx. 14 by total aggregate)
• Water (Approx. 12 by total aggregate)
• Aggregate (Type I, II or III)
• Cement
• Additives

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MAXIMUM ALLOWABLE THICKNESS OF SLURRY IS 1 ½
TIMES MAXIMUM ROCK SIZE
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SLURRY SEAL LIFE EXPECTANCY
7 YEARS LIFE SPAN AND LONGER WHEN USED FOR A
TRUE PREVENTIVE MAINTENANCE PROCEDURE
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SLURRY SEAL IS USED FOR

• Seal sound, oxidized pavements
• Restore surface texture by providing a
  skid-resistant wearing surface
• Improve waterproofing characteristics
• Correct raveling
• Provide a new surface where weight restrictions
  preclude the use of heavier overlays
• Alternative to a seal coat

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SLURRY SEAL SHOULD NOT BE USED TO

• Correct surface profile
• Fill potholes
• Alleviate cracking except for short-term weather
  protection
• Used on primarily new pavement

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PROPERTIES - SLURRY SEAL

• Surface treatment of equal thickness
• Thickness is equal to the largest stone of the
  component aggregate
• May be conventional or polymer modified aggregate
• Can be slow or quick setting
• Usually Cationic in nature

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PROPERTIES-SLURRY SEAL

• 6. Slow set breaks by evaporation
• Quick set breaks emulsions maintain a degree of
  chemical break
• Both systems are dependant on environmental
  conditions
• Quick set cures within an hour
• Slow set cures within a couple of hours

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RATE OF APPLICATION
Above Data taken from International Slurry
Surfacing Assn. 2007 Workshop and Valley Slurry
Seal website.
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SLURRY SEAL VS. SEAL COAT

• Vehicle damage less likely
• Wider temperature placement range
• Fewer personnel required for inspection
• Less materials testing
• Traffic speeds can be raised much sooner
• Life of a slurry seal
• Requires less equipment
• Requires a consistent plain from outside edge to
  inside edge
• Project can be completed in a shorter duration

• Greater possibility for vehicle damage
• Faster initial seal operation
• Requires more equipment for placement
• Traffic speeds reduced for longer period
• Life of a seal coat
• Placement unaffected by sloughs
• Seal coats lose chip
• Less expensive than slurry seal

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DIFFERENCES BETWEEN SLURRY SEAL AND MICROSURFACE

• SLURRY SEAL
• Mixture of emulsified asphalt, fine
  aggreagate,mineral filler, and water
• Best preventive maintenance for surfaces
• Seals surface, stops pavement raveling,
  smoothes and waterproofs
• Provides non-skid surface
• Cannot stack material
• Non-structural

• MICROSURFACE
• Polymer asphalt emulsion, selected Fine Grade
  Aggregate, mineral filler, water
• Can be placed at a thickness of up to 1.5
  (multiple layering is possible)
• Used for rut filling
• Provides non-skid surface
• Structural overlay

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2006 SLURRY SEAL VS. SEALCOATCOSTS

• GRAND FORKS SEALCOAT PROJ. PRICES
• Average price HFMS-2 . . . . . . . . . . .
  1.03 Gal
• Average Price CL 43 . . . . . . . . . . . .
  .22.85 Ton
• Price CRS-2P. . . . . . . . . . . . . . . . . .
  . 1.40 Gal
• Price CL 41 . . . . . . . . . . . . . . . . . . .
  . 30.00 Ton
• GRAND FORKS SLURRY SEAL PROJ. PRICES
• Asphalt Emulsion for Slurry Seal . 1.30
  Gal
• Agg. For Slurry Seal-Type II . . . . . . . 67.00
  Ton

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SLURRY SEAL VS. SEAL COATCOST COMPARISON PER
MILE

• GRAND FORKS SEAL COAT PROJ. PRICES
• Average price HFMS-2 . . . . . . . . . . . . .
  5,801
• Average Price CL 43 . . . . . . . . . . . . . . .
  4,022
• 9,823
• Price CRS-2P . . . . . . . . . . . . . . . . . .
  . . . 7,885
• Price CL 41 . . . . . . . . . . . . . . . . . . .
  . 5,280
• 
  13,165
• GRAND FORKS SLURRY SEAL PROJ. PRICES
• Agg. For Slurry Seal-Type II . . . . . . . . .
  9,827
• Asphalt Emulsion for Slurry Seal . . . . .
  6,333
• 16,160
• Quantities computed using 24 widths and no
  shoulders

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SLURRY SEAL COVERED UNDER SPECIAL
PROVISIONSP471(02)
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SPECIAL PROVISION

• Borrowed heavily from Nevada
• Issues addressed in SP Materials, Engineering,
  Equipment, Weather Limitations, Traffic Control,
  Surface Preparation, Application, Measurement

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SPECIAL PROVISION-AASHTO SPECIFICATION COVERAGE

• Additives
• 1. ISSA TB-139
• Emulsified Asphalt
• 1. AASHTO T59
• 2. AASHTO T49
• Aggregates
• 1. AASHTO T11 T27
• 2. AASHTO T2

• Deleterious Substances
• 1. AASHTO 176
• Soundness
• 1. AASHTO T104
• Hardness
• 1. AASHTO T96
• Moisture on weight of aggregate
• 1. AASHTO T19

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REQUIRED TESTS AND MIX DESIGN SPECIFICATIONS AS
PER SP 471(02)
The mixing test and set-time should be performed
at the highest temperatures expected during
construction.
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COMPONENT MATERIALS-SP 471(02)
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EMULSIONS

• CSS-1h
• CQS-1h ? emulsion used
• QS-1h
• SS-1h
• EMULSION SPECIFICATIONS ARE FORMULATED FOR
  CAPITIBILITY WITH THE AGGREGATE AND MEET MIX
  DESIGN PARAMETERS

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SPECIAL PROVISION-AGGREGATES

• Aggregate will be accepted at the job location or
  stockpile based on the passing average of 5
  gradation tests
• Deleterious substances
• Soundness
• Hardness

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AGGREGATES CHARACTORISTICS

• Geology-Compatibility, adhesion, and cohesiveness
  are affected
• Shape-Slurry aggregates must have fractured faces
  in order to form the required interlocking matrix
  (rounded aggregates result in poor mix strength)
• TextureRough surfaces bonds better with
  emulsions

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AGGREGATES CHARACTORISTICS-CONTINUED

• Age Reactivity-Aggregates the are crushed
  recently have a higher surface charge than
  weathered aggregates
• Clean Materials-Clay, dust, and silt can cause
  poor cohesion

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REASONS FOR FAILURE

• General wear
• Surface oxidation
• Abrasion under traffic
• Surface deflection
• Cracked surfaces
• Base or subgrade failure
• Delamination

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TEST SAMPLE DEPICTIING TOO MUCH MINERAL ADDITIVE
Segregation of aggregates Excessive moisture
around edges of sample Sample will be very slow
setting and may have to be removed from roadway

• Segregation of aggregates

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EXAMPLE OF AN ACCEPTABLE SLURRY SAMPLE

• Uniform aggregate throughout sample
• Minimal water puddling outside of sample

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RESULT OF TOO MUCH MINERAL ADDITIVE
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SLURRY CONTAINING EXCESSIVE WATER
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SLURRY WITH NOT ENOUGH MINERAL ADDITIVE

Note slurry is so stiff it holds in a
pile
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USING A CANVAS DRAG BEHIND REAR POLY SCREED
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PROJECTSSNH-6-081(063)163 U.S. 81 FROM MANVEL
TO LEVANTSNH-6-081(062)175U.S. 81 FROM ARDOCH
TO MINTO
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PROJECTS SCOPE OF WORK

• Slurry Seal both lanes
• using Type II aggregate for slurry and CQS-1H
  oil
• Slurry Seal U.S. 81 Manvel Intersection
• Prior to Slurry Seal, tack lanes using CSS1H
• Seal shoulders with CSS1H

• Seal and apply Class 44 Blotter to approaches
• Pre-install Plastic pavement marking Message for
  2 R/R crossings Stop bar at Manvel Intersection
• Epoxy Permanent Pavement Marking

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MIX DESIGN

• BEFORE WORK BEGINS
• A contractor submitted mix design covering
  the specific material to be used on the project
• A qualified laboratory shall present certified
  test results for the contractors approval.
• No substitution of materials will be permitted
  unless first tested and approved by the
  laboratory preparing the mix design.

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N.D.D.O.T. SLURRY SEAL SPECIAL PROVISION
471(02)GRADATION REQUIREMENTS
Aggregate is accepted at job location or
stockpile. The stockpile shall be accepted based
on 5 gradation tests according to AASHTO-T2 After
the mix design gradation is submitted, each sieve
shall not very by more than the stockpile
tolerance and still remain within the gradation
band.
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ACTUAL TARGET TEST RESULTS
Targets taken from lab results
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ROADWAY PREPARATION
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ROADWAY PREPARATION REPAIR CRACKS BEFORE
SEALING

• All cracks should be sealed and sealant allowed
  to cure
• Most cracks will reappear

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POOR CRACK REPAIR

• Cracks and subgrade problems should be properly
  repaired and ample time to cure prior to
  placement of slurry seal

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ROADWAY PREPARATION
Cracks 1/4 or greater should be filled with
crack sealing material and be allowed to cure
prior to slurry placement Crack sealant that has
not cured or that has been tacked may stick to
tires on the slurry paver
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ROADWAY PREPARATION
Slurry Seals are not designed to fix this
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ROADWAY PREPARATION-MUST BE MADE WITH TIME FOR
CURE BEFORE SEALING
Rutting must be repaired prior to slurry
seal. Pavement leaching oil will cause the slurry
seal to lift.
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ROADWAY PREPARATION

• Remove all organic materials from roadway
• Grind any existing plastic pavement marking to be
  slurry sealed over
• Repair roadway asphalt problems due to subgrade
• Seal all cracks and allow for cure time
• Asphalt patches with excessive oil can bleed
  threw slurry
• High pressure wash or grind oil spots
• Ensure construction equipment does not have oil
  or hydraulic leaks
• Broom ahead of slurry sealing
• Mark and cover all manholes, gate valve covers,
  curb inlets as needed
• Mark stop bars and messages to be reinstalled

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CALIBRATION

• Calibration of the aggregate using
• loader scale
• Receive a copy of
• the CALIBRATION
• SUMMARY
• If same materials are being used for multiple
  jobs, new calibration is not necessary
• ISSA requires minimum of recalibration every 6
  months
• Special provision allows engineer to request
  calibration at anytime

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Cement and aggregate meter
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CONTROL LINE

• Must fit the roadway especially when roads have a
  secondary or barely meet plan width

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SKID RUNNING ON CENTER EDGE
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ROADWAY PREPARATION

• Special Provision-Tack Coat, if required shall be
  applied with 3 parts water with a distributor at
  a rate of 0.10 0.15 gallons per square yard.
  This equals to .025 - .0375 gallons of tack only
  per yard.
• U.S. 81 worked best with minimum coverage

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WEATHER CONCERNS

• Medium to heavy rain can wash slurry seal oil
  from roadway
• Can cause aggregate separation
• May require total removal of damaged slurry seal
• Takes a minimum of an hour (plus) to be cured
  adequately

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TACK COAT
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PREFORMED PATTERNED PAVEMENT MARKING-MESSAGE

• Not recommended
• Spreader bar skids will cut into message if run
  over
• Stickiness of the tack coat can lift the
  temporary paper liner covering message, allowing
  slurry to cover and stain message

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OPERATIONS
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OPERATIONS
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SELF CONTAINED SLURRY SEAL/MICROSURFACING MACHINE
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SELF CONTAINED SLURRY SEAL/MICROSURFACING MACHINE
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SLURRY DRAGGING SHOULD NOT BE LONGER THAN 6
Hand work Dirty Screed
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EXCESSIVE SLURRY DRAGGING
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CONTROL LINE
Missed matching slurry at centerline due to bad
control line Good centerline control will
prevent such problems to include consistent
slurry seal lane widths and a cosmetically
pleasing job.
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PERIODIC MAINTENANCE/CLEANING IS NECESSARY
THROUGHOUT DAY
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Slurry sealing requires constant adjustments.
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SLURRY SEAL PLACEMENT PROBLEMS
If the outside skid gets too close to the
rounded edge of existing pavement, the slurry box
may slide and cause the box to vibrate or jump.
This can cause a washboarding effect on the
slurry surfacing.
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EDGE LINE
A good control line will aide in a smooth and
straight edge line.
Notice slurry material is leaking between the
primary screed allowing the slurry to cover
beyond the skids
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HEADERS
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HEADERS
When cleaning in front of the header, make sure
emulsion is not washed off of the placed slurry
seal
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CLEANING SPREADER AT HEADER
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TAKING OFF FROM A HEADER
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COMING OFF A BRIDGE DECK
Use of roofing paper and duct tape to cover edge
of bridge deck
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TRAFFIC CONTROL
Usually, within an hour, the slurry can carry
traffic but not excessive twisting/turning of
heavy equipment
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EPOXY PAVEMENT MARKING
Moisture in slurry can continue to leach long
after placement, causing damage to permanent
pavement marking. A minimum of four weeks
between slurry placement and permanent pavement
marking placement is recommended. Epoxy pavement
marking was placed about 3 weeks after completion
of slurry seal.
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MORE EPOXY PAVEMENT MARKING DAMAGE
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CONSTANT CLEANING AND MAINTENANCE IS THE KEY TO A
QUALITY JOB
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TACKED SURFACE NEST TO SLURRY SEALED SURFACE
Notice relatively straight centerline
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EXAMPLE OF QUALITY LAYDOWN
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ADDITIONAL INFORMATION-ITEMS TO MONITOR

• Ensure calibration is completed before placement
  of slurry seal or calibration data is provided
  from previous project (using same materials)
• Ensure inappropriate materials do not contaminate
  slurry from digging too low in stockpile
• Monitor stockpile segregation
• Is moisture in stockpile consistent (a new mix
  design may be necessary if moisture changes
  dramatically

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ADDITIONAL INFORMATION-ITEM TO MONITOR

• Recommend, as a minimum, calculating aggregate
  cut off at end of each day (the difference
  between the slurry machines dial reading
  calculation and total tonnage hauled by totaling
  tickets for comparison)
• Monitor air and surface temperatures for limits
  as specified in the special provision
• Monitor weather
• Monitor roadway ahead for last minute
  contamination
• Take periodic depth checks of placed slurry seal
  make sure to stay within thickness spec.
• Check yield on a regular basis
• Monitor slurry for minimal drag marks, should to
  exceed 6
• Ensure the centerline overlap does not create a
  safety hazard due to buildup of slurry on edge

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ADDITIONAL INFORMATION-ITEMS TO MONITOR

• Adjust squeegee (secondary strike-off) angle for
  best or preferred surface texture
• Ensure traffic control is maintained and minimal
  delays to the public
• Monitor construction equipment for leaking fluids
• Acquire samples of materials, as required
• Watch for slurry not overlapping at centerline
• Periodic measurement of slurry seal widths

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ADDITIONAL INFORMATION-ITEMS TO MONITOR

• Watch for washboard effect in the placed slurry
  seal
• Keep material haulers from driving on fresh tack
• Watch for leaking equipment
• Over filled cracks can create problems-skids can
  hook material and drag it. Small pieces can than
  cause dragging problems when placing the slurry

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EXAMPLE OF EXCEL SPREADSHEET YIELD CHECK
Green are required inputs and yellow shows
desired information
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TICKET WEIGHT COMPARED TO PLAN YIELD CHECK USING
EXCEL SPREADSHEET
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PLAN SLURRY SEAL-MANVEL INTERSECTION
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SLURRY SEAL PLACEMENT DAY 1-MANVEL INTERSECTION
Slurry seal is basically placed in straight
lines, overlapping. It is difficult to turn the
slurry seal machine sharp enough to turn most
intersections
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SLURRY SEAL PLACEMENT DAY 2-MANVEL INTERSECTION
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USE OF SPOTTING TABS

• Spotting tabs, if used for centerline control,
  can create a void as the tab is knocked down by
  the slurry box
• The tab can be torn away by the slurry box skid
  or the squeegees
• Are used for marking utility holes, stop bars,
  inlets, etc.

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EXAMPLE OF FIELD EXPEDIANT SLURRY SEAL FOOT WEAR
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USEFUL WEBSITES

• Valley Slurry Seal Co
• http//www.slurry.com/equip_microsurfacing.shtml
• International Slurry Surfacing Association
• http//www.slurry.org/
• MNDOT
• http//www.mnltap.umn.edu/pdf/asphalt.pdf
• Intermountain Slurry
• http//www.intermountainslurry.com/services_UT.ht
  m