Fog Seals, Sand Seals, Scrub Seals, and Rejuvenators

Learning Outcomes 1. List benefits of fog seals, scrub seals, sand seals, and rejuvenators 2. Describe recommended materials 3. Describe recommended construction procedures 4. List key quality control activities

Learning Outcomes (cont.) 5. Describe potential construction and performance problems 6. Identify troubleshooting solutions

Description Spray application of asphalt emulsion Treatment differences – Emulsion type – Use of aggregate – Method of embedment Application rate, timing, and construction quality are critical

Benefits Slowed aging process Waterproofed surface Prevention of stone loss Increased surface friction Better surface appearance

[Nitrogen Bases] [Paraffins] Asphalt Components

What is an emulsion? Mixture of asphalt binder, water, and emulsifying agent 50 to 75% of mix is asphalt “Breaking” — separation of water and asphalt “Curing” — development of asphalt mechanical properties

Emulsion Ingredients Asphalt – Slow setting : up to 43% water – Rapid setting : up to 35% water Water : Impurities can be harmful Emulsifying agent (surfactant)

Emulsion Classification Electrical charge Speed of break: slow (SS), medium (MS), and rapid set (RS) Asphalt relative viscosity: hard (h) or soft (s) Polymer-modified asphalt (P or L)

CRS - 2 cationic CSS - 1h hard asphalt HFMS - 2s 65% asphalt with solvent Emulsion Classification Names cationic high-float medium-setting (anionic) slow-setting rapid-setting high viscosity (65% asphalt) 57% asphalt

Emulsion Type Slow Setting Medium Setting Rapid Setting AnionicSS-1 SS-1h MS-1 MS-2 MS-2h HFMS-1 HFMS-2 HFMS-2h HFMS-2s RS-1 RS-2 HFRS-2 CationicCSS-1 CSS-1h CMS-2 CMS-2h CRS-1 CRS-2 Emulsion Classification

Emulsion Distribution of Asphalt Particles mm ( in)

Emulsion Terminology Original emulsion—asphalt, water, and emulsifying agent Diluted emulsion—original emulsion diluted by additional water Residual asphalt content—amount of asphalt left after water has evaporated

Aggregate Applied to sand and scrub seals Clean material, smaller than 2 mm (0.08 in)

Fog Seals

Fog Seals Description Light application of diluted slow-setting asphalt emulsion Common uses – Seal aged surface – Improve lane delineation Cost: 0.15 to 0.20 $/m 2 (0.12 to 0.17 $/yd 2 ) Typical treatment life: 1 to 2 years

Fog Seals Application Considerations Seal must penetrate surface voids Environment affects both break and future performance Allowing traffic before break is hazardous!

Fog Seals Suitable Surfaces Heavily aged, dense-graded HMA Open-graded HMA

Dense-graded HMA with closed surface Dense-graded HMA with closed surface Fog Seals Unsuitable Surface

Fog Seals Before and After Fog seal over existing chip seal

Fog Seal Construction 1.Surface preparation 2.Material preparation 3.Emulsion application 4.Sand blotter and sweeping (if necessary)

Fog Seal Construction Confirmation of Site Conditions Consideration of site conditions is essential to proper curing Little or no chance of rain Temperature conditions – Air: 5 °C (40 °F) – Pavement: 15 °C (60 °F)

Fog Seal Construction Pavement Surface Preparation

Fog Seal Construction Materials Preparation Slow setting emulsion recommended Check compatibility of water used to dilute the emulsion Dilute emulsion no more than 24 hours before application

Fog Seal Construction Emulsion Application

Fog Seal Construction Emulsion Application—Distributor Calibration Pre-construction Pump rate Application rate Coverage test

Fog Seal Construction Emulsion Application Application rate: 0.45 to 0.70 l/m 2 (0.10 to 0.15 gal/yd 2 ) Spray temperature range: 20 to 70 °C (70 to 160 °F)

Spray Bar and Nozzles Single Overlap Fog Seal Construction Asphalt Distributor—Spray Bar Height h h Roadway Surface Double Overlap Roadway Surface Triple Overlap Roadway Surface h

15 o 45 o 90 o Travel Direction Lateral Coverage Fog Seal Construction Asphalt Distributor—Spray Nozzles

Fog Seal Construction Post Treatment Procedures Sand blotter and sweeping (if necessary) Pavement should NOT be opened to traffic until adequate friction is restored

Sand Seals Description Spray emulsion followed by a light covering of sand Improves friction “Locks” a chip seal Cost: 0.40 to 0.80 $/m 2 (0.33 to 0.66 $/yd 2 ) Typical treatment life: 3 to 6 years

Sand Seals Application Considerations Low-speed, lower volume roads Typically 2 to 5 mm (0.1 to 0.2 in) thick Not as good a delineator as fog seal

Sand Seal Construction 1.Surface preparation 2.Material preparation 3.Emulsion application 4.Sand application 5.Rolling

Sand Seal Construction Emulsion Application Rapid setting typical, no dilution Application rate: 0.70 to 1.25 l/m 2 (0.15 to 0.28 gal/yd 2 ) Spray temperature range: RS-120 to 60 °C (70 to 140 °F) MS-1, HFMS-120 to 70 °C (70 to 160 °F) RS-2, HFRS-2, CRS-1, CRS-2 50 to 85 °C (125 to 185 °F)

Sand Seal Construction Application of Sand Clean, typically < 2 mm (0.08 in) Application rate: 5.5 to 12 kg/m 2 (10 to 22 lb/yd 2 ) Surface temperature: >15 °C (60 °F) Sand applied with a spreader immediately after spray emulsion

Sand Seal Construction Post Treatment Procedures Embedment with pneumatic-tired rollers Open to traffic: ~ 2 hours

Scrub Seals

Scrub Seals Description Spray applied emulsion, drag-broomed, lightly sanded, drag-broomed again, and rolled Fills surface voids and cracks Cost: 0.60 to 1.00 $/m 2 (0.50 to 0.83 $/yd 2 ) Typical treatment life: 3 to 6 years

Scrub Seals Application Considerations Low to moderate volume roadways Brushing works emulsion into pavement surface Can be applied in multiple layers Thickness from 10 to 40 mm (0.4 to 1.5 in)

Scrub Seal Construction 1.Surface and material preparation 2.Emulsion application 3.Initial drag-brooming of surface 4.Sand application 5.Second drag-brooming of surface 6.Rolling

Scrub Seal Construction Emulsion Application Polymer-modified emulsion Application rate: 0.63 to 0.82 l/m 2 (0.14 to 0.18 gal/yd 2 ) Emulsion temperature: 44 to 71°C (110 to 160 °F) Pavement temperature: 21 to 32 °C (70 to 90 °F)

Scrub Seal Construction Initial Drag-Brooming of Surface

Scrub Seal Construction Sand Application Application rate: 6.5 to 8.1 kg/m 2 (12 to 15 lb/yd 2 ) Minimum of two roller passes

Scrub Seal Construction Second Drag-Brooming and Rolling

Rejuvenators Emulsions that include asphalt, polymer latex, and other additives Softens existing binder Trade names: – Reclamite – PASS – Topien C

Rejuvenator Application

Rejuvenator Application Application of Sand

Fog Seals, Sand Seals, Scrub Seals, and Rejuvenators QUESTIONS?