TRANSPORTATION IMPROVEMENT BOARD OTTA SEAL Using High Float

TRANSPORTATION IMPROVEMENT BOARD OTTA SEAL Using High Float Emulsions (HF-150)

Otta Seal is a surface treatment that uses a medium of rock that interlocks with each other like hotmix. It is made by placing the rock medium on top of a thick application of relatively soft, bituminous binding agent such as HF-1501. Otta Seal can look like gravel after immediate installation, but over time the black oils will work their way up creating the appearance of a normally paved surface. 1 Johnson, G., & Pantelis, J. 2003, 2008. Otta Seal Surfacing of Aggregate Roads. http://www.dot.state.mn.us/materials/bituminousdocs/Pavement%20Maintenance/OttaSeal 4-pagerMRR 2008.pdf Transportation Improvement Board Otta Seal Overview What is Otta Seal?

Chip Seal is one layer of clean rock that requires enough oil to secure it. It is one of the oldest and most common street-surfacing methods1. 1 Chip Seal Brochure. https://static.spokanecity.org/documents/projects/2021-residential-chip-seal/chip-seal-brochure.pdf Transportation Improvement Board Chip Seal Overview Recap of Chip Seal

Advantages of Otta Seal Otta Seal Costs less than washed rock, saving money for agencies Less brittle at low temperatures, less prone to temperature related failure Does not bleed like base AC emulsions Holds rock medium better Chip Seal While effective, the medium is more expensive and less accessible to smaller agencies and communities More susceptible to weather and traffic damage Lasts about half the lifespan of Otta seal Fines in the rock can fill in cracks and voids Otta seal can last 8 to 15 years or more with proper maintenance Asphalt Surfacing. https://web.archive.org/web/20120426011304/http://www.cflhd.gov/programs/techDevelopment/pavement/context-roadwaysurfacing/documents/roadway-surfacing-photos/ch1-c-asphalt.pdf Johnson, G., & Pantelis, J. 2003, 2008. Otta Seal Surfacing of Aggregate Roads. http://www.dot.state.mn.us/materials/bituminousdocs0 /Pavement%20Maintenance/OttaSeal 4-pagerMRR 2008.pdf Transportation Improvement Board Otta Seal Advantages

Process for Single Shot Otta Seal on Paved Surface Step Two Step Three Lay down materials Apply oil Allow oil to penetrate Apply cover stone Roll with two rollers One roller should be a steal drum This seals the treatment Return after three weeks and sweep excess rock Transportation Improvement Board Single Shot on Paved Surface Step One Photos from Creston, WA Otta Seal Project!

Process for Double Shot Otta Seal on Gravel Surface Step Two Step Three Step Four Lay down materials Apply oil Allow oil to penetrate Apply cover stone Roll with two rollers One roller should be a steal drum This seals the treatment After 7-10 days, apply second layer of materials Place with oil Apply cover stone Return after three weeks and sweep excess rock Transportation Improvement Board Double Shot on Gravel Surface Step One

Differences in Oils High Float Emulsion (HF-150) Conventional Emulsions Easier to handle than cationic oils Sets much more quickly More forgiving emulsion Relies on kerosene evaporation Works well with crushed stone Works with more expensive, aggregate washed aggregate Saves money due to materials used Transportation Improvement Board Differences in Oils

Application Rate for Otta Seal on Paved Surface Undiluted Asphalt (gal/sy) 0.45 - 0.50 Aggregate Size Crushed Cover Stone Aggregate Application (lbs/sy) 30 - 35 Process for Otta Seal on a Paved Surface Apply 0.45-0.50 gal/sy HF-150 to compacted gravel surface. Let it penetrate. Apply 30-35 lbs/sy cover stone. Due to low volume traffic, ensure extra rolling effort with two rollers (at least one shall be a steel drum) to seat the cover. Optional- After 3 weeks of placement, sweep excess rock. Transportation Improvement Board Otta Seal on a Paved Surface

Application Rate for Otta Seal on Gravel Surface Undiluted Asphalt (gal/sy) Aggregate Size First Application 0.45 0.50 Crushed Stone Cover Second Application 0.40 0.44 Crushed Stone Cover Aggregate Application (lbs/sy) 30 35 30 32 Process for Otta Seal on a Surface Apply 0.45-0.50 gal/sy HF-150 to compacted gravel surface. Let it penetrate. Apply 30-35 lbs/sy cover stone. Due to low volume traffic, ensure extra rolling effort with two rollers (at least one shall be a steel drum) to seat the cover. Second application- Seal again with 0.40-0.44 gal/sy HF-150 Apply 30-32 lbs/sy cover stone. Again, extra rolling effort which includes a steel drum roller. Optional- After 3 weeks of placement of second application, sweep excess rock. The second application should be applied 7-10 days after the first application. Transportation Improvement Board Otta Seal on a Gravel Surface

Additional Specifications Crushed Cover Stone Specifications Tes t Requiremen t 3/4” Sieve Square 100% passing 5/8” Sieve Square 95-100% passing No. 4 20-45% passing No. 200 0-7.5% passing % Fracture by weight, min. 75 % Sand Equivalent 40 min Static Test Pass Stripping Oil Specifications for HFE-150 Min. F 13 0 Max. F 17 5