Presentation on theme: "SLURRY SEAL PROJECTS By Richard Sampson & Dustin Lang."— Presentation transcript:
SLURRY SEAL PROJECTS By Richard Sampson & Dustin Lang
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.
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
MAXIMUM ALLOWABLE THICKNESS OF SLURRY IS 1 ½ TIMES MAXIMUM ROCK SIZE
SLURRY SEAL LIFE EXPECTANCY 7 YEARS + LIFE SPAN AND LONGER WHEN USED FOR A TRUE PREVENTIVE MAINTENANCE PROCEDURE
SLURRY SEAL IS USED FOR: 1.Seal sound, oxidized pavements 2.Restore surface texture by providing a skid-resistant wearing surface 3.Improve waterproofing characteristics 4.Correct raveling 5.Provide a new surface where weight restrictions preclude the use of heavier overlays 6.Alternative to a seal coat
SLURRY SEAL SHOULD NOT BE USED TO: 1.Correct surface profile 2.Fill potholes 3.Alleviate cracking except for short-term weather protection 4.Used on primarily new pavement
PROPERTIES- SLURRY SEAL 1.Surface treatment of equal thickness 2.Thickness is equal to the largest stone of the component aggregate 3.May be conventional or polymer modified aggregate 4.Can be slow or quick setting 5.Usually Cationic in nature
PROPERTIES-SLURRY SEAL 6. Slow set breaks by evaporation 7.Quick set breaks emulsions maintain a degree of chemical break 8.Both systems are dependant on environmental conditions 9.Quick set cures within an hour 10.Slow set cures within a couple of hours
RATE OF APPLICATION AGGREGATE TYPE LOCATIONSUGGESTED APPLIATION RATE TYPE IParking Areas, Airport Runways 8-12 lb./sq. yd. TYPE IIGeneral Purpose, Urban & Residential Streets, Arterial Routes, Highways lb./sq. yd. TYPE IIIHigh Speed Roads, Industrial Estates lb./sq. yd. Above Data taken from International Slurry Surfacing Assn Workshop and Valley Slurry Seal website.
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
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
2006 SLURRY SEAL VS. SEALCOAT COSTS GRAND FORKS SEALCOAT PROJ. PRICES Average price HFMS $ 1.03 Gal Average Price CL $22.85 Ton Price CRS-2P $ 1.40 Gal Price CL $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
SLURRY SEAL VS. SEAL COAT COST COMPARISON PER MILE GRAND FORKS SEAL & COAT PROJ. PRICES Average price HFMS $ 5,801 Average Price CL $ 4,022 $ 9,823 Price CRS-2P $ 7,885 Price CL $ 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
SLURRY SEAL COVERED UNDER SPECIAL PROVISION SP471(02)
SPECIAL PROVISION Borrowed heavily from Nevada Issues addressed in SP: Materials, Engineering, Equipment, Weather Limitations, Traffic Control, Surface Preparation, Application, Measurement
REQUIRED TESTS AND MIX DESIGN SPECIFICATIONS AS PER SP 471(02) ISSA TESTDESCRIPTIONSPECIFICATION NO. ISSA TB-106Slurry Seal Consistency3 cm Maximum ISSA 30 Minutes (Set)12 kg-cm Minimum 77 degrees F.West cohesion at 60 Minutes20kg-cm Minimum ISSA TB-109Excess Asphalt by LWT Sand Adhesion 50 g/sq. ft. Maximum ISSA TB-114Wet Stripping Pass (90% Minimum) ISSA TB-100Wet-Track Abrasion Loss, One-hour Soak75 g/sq.ft. ISSA TB-113Mix Time*Controllable to 180 Seconds Minimum *The mixing test and set-time should be performed at the highest temperatures expected during construction.
COMPONENT MATERIALS-SP 471(02) Residual Asphalt8.0% to 13.5% by dry weight of aggregate Mineral Filler0.5% to 2.0% by dry weight of aggregate Field Control Additive As required to provide the specified properties and meet the wet cohesion requirements WaterAs required to provide consistency
EMULSIONS 1.CSS-1h 2.CQS-1h emulsion used 3.QS-1h 4.SS-1h EMULSION SPECIFICATIONS ARE FORMULATED FOR CAPITIBILITY WITH THE AGGREGATE AND MEET MIX DESIGN PARAMETERS
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
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) Texture:Rough surfaces bonds better with emulsions
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
REASONS FOR FAILURE General wear Surface oxidation Abrasion under traffic Surface deflection Cracked surfaces Base or subgrade failure Delamination
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
EXAMPLE OF AN ACCEPTABLE SLURRY SAMPLE Uniform aggregate throughout sample Minimal water puddling outside of sample
RESULT OF TOO MUCH MINERAL ADDITIVE
SLURRY CONTAINING EXCESSIVE WATER
SLURRY WITH NOT ENOUGH MINERAL ADDITIVE Note: slurry is so stiff it holds in a pile
USING A CANVAS DRAG BEHIND REAR POLY SCREED
PROJECTS: SNH-6-081(063)163 U.S. 81 FROM MANVEL TO LEVANT & SNH-6-081(062)175 U.S. 81 FROM ARDOCH TO MINTO
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
MIX DESIGN BEFORE WORK BEGINS: 1.A contractor submitted mix design covering the specific material to be used on the project 2.A qualified laboratory shall present certified test results for the contractor’s approval. 3.No substitution of materials will be permitted unless first tested and approved by the laboratory preparing the mix design.
N.D.D.O.T. SLURRY SEAL SPECIAL PROVISION 471(02) GRADATION REQUIREMENTS STOCKPILE SIEVE SIZETYPE II-% PASSINGTOLERANCE 3/8" % # % # % # % # % # % # % # 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.
ACTUAL TARGET TEST RESULTS SNH-6-081(063)163 & SNH-6-081(062)175 TYPE II-% PASSING DESIGN VALUES (MIX DES. RESULTS) STOCKPILE TOLERANCE SIEVE SIZE3/8"#4#8#16#30#50#100#200 SAMPLE A SAMPLE B SAMPLE C SAMPLE D SAMPLE E OVER/UNDER TARGET Targets taken from lab results
ROADWAY PREPARATION REPAIR CRACKS BEFORE SEALING All cracks should be sealed and sealant allowed to cure Most cracks will reappear
POOR CRACK REPAIR Cracks and subgrade problems should be properly repaired and ample time to cure prior to placement of slurry seal
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
ROADWAY PREPARATION Slurry Seals are not designed to fix this
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.
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
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
Cement and aggregate meter
CONTROL LINE Must fit the roadway especially when roads have a secondary or barely meet plan width
SKID RUNNING ON CENTER EDGE
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 gallons of tack only per yard. U.S. 81 worked best with minimum coverage
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
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
SLURRY DRAGGING SHOULD NOT BE LONGER THAN 6” Hand work Dirty Screed
EXCESSIVE SLURRY DRAGGING
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.
PERIODIC MAINTENANCE/CLEANING IS NECESSARY THROUGHOUT DAY
Slurry sealing requires constant adjustments.
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.
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
When cleaning in front of the header, make sure emulsion is not washed off of the placed slurry seal
CLEANING SPREADER AT HEADER
TAKING OFF FROM A HEADER
COMING OFF A BRIDGE DECK Use of roofing paper and duct tape to cover edge of bridge deck
TRAFFIC CONTROL Usually, within an hour, the slurry can carry traffic but not excessive twisting/turning of heavy equipment
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.
MORE EPOXY PAVEMENT MARKING DAMAGE
CONSTANT CLEANING AND MAINTENANCE IS THE KEY TO A QUALITY JOB
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
ADDITIONAL INFORMATION- ITEM TO MONITOR Recommend, as a minimum, calculating aggregate cut off at end of each day (the difference between the slurry machine’s 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
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
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
EXAMPLE OF EXCEL SPREADSHEET YIELD CHECK DATE AUG TIME 17:13 BEGEND RATELBSTONSOILOIL USEDOIL WTGAL USD REV DIFFON DIALUSED BY DIAL PER GALBY DIAL BEGEND YIELD STATION DIFFWIDTHSQ YDSBY DIAL Green are required inputs and yellow shows desired information
TICKET WEIGHT COMPARED TO PLAN YIELD CHECK USING EXCEL SPREADSHEET SLURRY SEAL DIALS COMPARED TO TICKET TONNAGE TYPE II TONNAGE AGG. OIL CUMPUTED FROM FROMYIELD BYPLAN RATE OVER RUN ACTUAL TONS COMPARED TICKETSTICKET PLAN YIELD UNDER RUN TO DIAL
PLAN SLURRY SEAL-MANVEL INTERSECTION
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
SLURRY SEAL PLACEMENT DAY 2-MANVEL INTERSECTION
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.
EXAMPLE OF FIELD EXPEDIANT SLURRY SEAL FOOT WEAR
USEFUL WEBSITES Valley Slurry Seal Co ml International Slurry Surfacing Association MNDOT Intermountain Slurry