Slurry Seal and Micro-Surfacing Systems
SLURRY SEAL – WHAT IS IT?
It is not the same as seal coat and was developed in the 1930’s in Germany. Slurry seal is a cold mix coating consisting of fine crushed aggregate, emulsified asphalt, additives and water applied to roadways. Emulsion serves as a binder to hold the aggregate together and to adhere to the roadway. It is a very economical way to maintain asphalt roadways but has no structural value. Slurry seal has a ambient temperature cure.
MICRO SURFACING – WHAT IS IT?
Slurry Seal was expanded upon in the late 1960’s and early 1970’s in an attempt to use slurry in thicker applications that could be applied in narrow courses in wheel ruts to avoid not having to replace expensive traffic delineation on the autobahns. High quality aggregates and advanced emulsions where incorporated which resulted in a stable product when applied in multi-stone thickness. Micro surfacing can be applied in multi-layer surfaces.
WHAT DOES IT TAKE?
- Slurry Trucks/Specialized Equipment
- Quality Aggregate
- Quality Emulsion- with Polymers
- Working Mix Design
- Equipment Calibrations / Verification
- Test Strips / Verification
- Trained Personnel
- Not overstating product capabilities
- Partnership with owner, suppliers and crew
- Slurry or Micro Performance
FACTORS TO CONSIDER
- Existing pavement condition
- Surface Preparation, Weeding, Crack Sealing, Patch Repairs (fog seal new patches), Trees, Cleaning and Striping removal
- Traffic levels and Traffic Control Requirements
- Stockpile Location
- Climate and Weather Conditions
- Day or Night Application Hours
- Parking Configurations-Power Steering Scuffing
- Reflective Cracking
- Ravel or shedding of product
- Urban vs. rural settings
- Availability of materials
SLURRY SEAL TYPES
Slurry seal is used to correct minor defects such as halts raveling, restores loss of matrix, and improves skid resistance.
There are 3 types of slurry seal:
- Type 1 – Bike or walking trails, parking lots
- Type 2 – Residential roadways
- Type 3 – Highways, collectors, and arterial
Slurry seal is low cost with good performance at an expected service life of 4-7 years.
Slurry surfacing is laid at one-stone thickness. The largest stone bears the traffic load and it is not designed for mutiple layering.
What makes micro surfacing different than slurry seal?
Higher polymer content in the emulsion
Higher asphalt residual content
Fast setting chemicals – allows faster break
Requires higher quality aggregate
Higher quality control required with the system
Is able to support traffic as quick as one hour after placement
Micro has only Type II and Type III applications
ABOUT MICRO SURFACING
- Suited for higher volume collectors, arterials and highways
- Night Time Application
- Minor Rut Filling
- Double Applications for addressing surface irregularities
- Not intended for a lot of hand work
MICRO SURFACING APPLICATION
- Applied in multi-stone thickness
- Stone interlock and modified binder bears traffic load
- May be applied in multiple layers
- Pre Cleaning & Post Sweeping
- Proper Prep; Tree trimming, Weeding, Crack Sealing, Patching, Striping Removal
- Stockpile Management, Management of Externals
- Hand Work
- Housekeeping – Lay-down Box – Squeegee
- Drag Marks
- Transverse and Longitude Joints
- Motorists driving thru the work
- Color Variance – Uniform Surface
- Placement – Thickness – Gradation
- Slurry’s & Micro’s Best Friend: Traffic, Time and Weather