Comal County Chip Sealing

June 26, 2007

Chip sealing is the application of a bituminous binder immediately followed by the application of an aggregate. The aggregate is then rolled to embed it into the binder.

Binder Application

Aggregate Application

Rolled

Advantages of Chip Sealing

• Improved Skid Resistance

• Cost Effective Treatments

• Good Durability (Typically 5-7 Years)

• Ease of Construction

• Chip Seal = 1 Mile/Day

• Asphalt = 1 Mile/Week

Disadvantages of Chip Sealing

• Flying Chips – Broken windshields and vehicle damage

• Noise Considerations – Chip seals can be noisy to travel on

• Weather Considerations – Must be constructed during warm, dry weather during daytime only

• Pedestrian – Not good for roller-blading & skateboarding

Materials

Binders must provide good adhesion,

or stickiness

Aggregates must have following characteristics:• Single-sized, if possible• Clean• Angular (not rounded)• Aggregates must be damp for emulsion use

Construction Process

Surface Preparation

• Crack Sealing or Filling of Cracks

• Patching Deteriorated Areas

• Cleaning or Brooming Any Loose Material

• Removing Pavement Markers and Delineators

Construction Process

Binder Application

• Uniformly Apply the Binder Over the Surface at a Designed Rate

• Pavement Surface Temperature Should be 55ºF and Rising

• Humidity Should be 50% or Lower

• Most Important Step in Process

Construction Process

Aggregate Application

• Should Follow the Binder Application by no more than 90 Seconds

• Should be no more than 100 Feet Behind Distributor Truck

Construction Process

Aggregate Application

• Should Follow the Binder Application by no more than 90 Seconds

• Should be no more than 100 Feet Behind Distributor Truck

Construction ProcessRolling

• Initial Rolling by Pneumatic Roller or Steel Rollers

• Compaction by Traffic Finishes the Process

• Should be Done During Hotter Weather

• Should Follow Aggregate Spreading by no more than 500 Feet

• Minimum of Two Rollers Should be Used to Cover the Full Width of the Chip Spreader

Construction ProcessBrooming

• After Chip Seal, Excess Aggregate Must be Broomed Off

• Within 2 to 4 Hours after Sealing

Possible Problems

• Bleeding – Too much binder leading to “leaking” of emulsion

• Traffic Control – Ensure that vehicles do not drive on binder application

• “Shelling” – Aggregate not applied in a timely manner. Binder sets. Aggregate does not stay in place.

Comal County Canyon Lake

Spillway Canyon

June 26, 2007

1998 Storm Totals

Storm Total for 1998

Storm Total for 2002

Structural Flood Control Measures in Comal County

Canyon Reservoir

Structural Flood Control Measures in Comal County

Emergency Spillway

Structural Flood Control Measures in Comal County

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