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SLURRY SEAL PROJECTS

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.

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SLURRY SEAL PROJECTS

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  1. SLURRY SEAL PROJECTS By Richard Sampson & Dustin Lang

  2. 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.

  3. 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

  4. MAXIMUM ALLOWABLE THICKNESS OF SLURRY IS 1 ½ TIMES MAXIMUM ROCK SIZE

  5. SLURRY SEAL LIFE EXPECTANCY 7 YEARS + LIFE SPAN AND LONGER WHEN USED FOR A TRUE PREVENTIVE MAINTENANCE PROCEDURE

  6. 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

  7. 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

  8. 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

  9. 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

  10. RATE OF APPLICATION Above Data taken from International Slurry Surfacing Assn. 2007 Workshop and Valley Slurry Seal website.

  11. 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 SLURRY SEAL VS. SEAL COAT

  12. 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 DIFFERENCES BETWEEN SLURRY SEAL AND MICROSURFACE

  13. 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

  14. 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

  15. SLURRY SEAL COVERED UNDER SPECIAL PROVISIONSP471(02)

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

  17. 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 SPECIAL PROVISION-AASHTO SPECIFICATION COVERAGE

  18. 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.

  19. COMPONENT MATERIALS-SP 471(02)

  20. 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

  21. 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

  22. 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

  23. 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

  24. REASONS FOR FAILURE • General wear • Surface oxidation • Abrasion under traffic • Surface deflection • Cracked surfaces • Base or subgrade failure • Delamination

  25. 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

  26. EXAMPLE OF AN ACCEPTABLE SLURRY SAMPLE • Uniform aggregate throughout sample • Minimal water puddling outside of sample

  27. RESULT OF TOO MUCH MINERAL ADDITIVE

  28. SLURRY CONTAINING EXCESSIVE WATER

  29. SLURRY WITH NOT ENOUGH MINERAL ADDITIVE Note: slurry is so stiff it holds in a pile

  30. USING A CANVAS DRAG BEHIND REAR POLY SCREED

  31. PROJECTS:SNH-6-081(063)163 U.S. 81 FROM MANVEL TO LEVANT&SNH-6-081(062)175U.S. 81 FROM ARDOCH TO MINTO

  32. 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 PROJECTS SCOPE OF WORK

  33. 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 contractor’s approval. • No substitution of materials will be permitted unless first tested and approved by the laboratory preparing the mix design.

  34. 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.

  35. ACTUAL TARGET TEST RESULTS Targets taken from lab results

  36. ROADWAY PREPARATION

  37. ROADWAY PREPARATION REPAIR CRACKS BEFORE SEALING • All cracks should be sealed and sealant allowed to cure • Most cracks will reappear

  38. POOR CRACK REPAIR • Cracks and subgrade problems should be properly repaired and ample time to cure prior to placement of slurry seal

  39. 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

  40. ROADWAY PREPARATION Slurry Seals are not designed to fix this

  41. 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.

  42. 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

  43. 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

  44. Cement and aggregate meter

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

  46. SKID RUNNING ON CENTER EDGE

  47. 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

  48. 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

  49. TACK COAT

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