Chris Sajbel Pecora Corporation Roadway Joints Chris Sajbel Pecora Corporation

Movement Capability.. Movement Capability- The +/- percent value that indicates the amount of movement the sealant can take in “extension (+)” and/or “compression (-)” from it’s original cured joint width. Sealants are characterized by their type and their movement capabilities: +/- 12.5% +/- 25% +/- 50% +100%/-50% These are the 4 standard classifications of joint sealants. Decisions should be made accordingly.

FAA Joint Types FAA Publication AC 150/5320-6D

Bond Durability or Movement Class ASTM C-719 Class 12.5 +/- 12.5 % Class 25 +/- 25 Class 50 +/- 50 Class 100 +100 / -50 Must pass 10 cycles after aged compression @ 160 F and water immersion with extension temperatures down to -15 F Look for SWRI Validation

Joint Configuration Width to depth ratios guidelines Purpose: Maximize sealant performance Vertical Joints Joints up to 1/2 ” wide: 1:1 width to depth Joints up to 1.0” wide: 2:1 width to depth Joints > 1.0”: Max .50” depth Horizontal Traffic Joints Joints up to 1/2 “ wide: 1:1 width to depth Joints > 1.0” (pedestrian) : 1:1 width to depth Joints > 1.0” (vehicular): 2:1 width to depth

Sealant Types Cold applied – Polyurethane, STPU, Silicone Hot applied Preformed Polychloroprene elastomeric (neoprene) compression sealant CSS-69 There are three categories of joint sealant materials, as shown in the accompanying slide. Selection of the sealant type is generally based on the specific design details of the project, desired performance, and cost. DISCUSS THE RELATIVE MERITS OF EACH OF THESE SEALANT TYPES IN TERMS OF INITIAL COST AND EXPECTED LONGEVITY. ASK WHAT TYPE OF SEALANTS ARE ROUTINELY USED. ARE DIFFERENT SEALANTS USED FOR MAINTENANCE ACTIVITIES THAN FOR NEW CONSTRUCTION?

Sealant Types Cold Applied Hot Applied Preformed CSS-71 Cold Applied Partial Depth Cold Applied Full Depth Pre-formed Seal CSS-71 Figure: The various sealant types have different requirements for the configuration of the sealant reservoir. Note that cold and hot applied sealants typically require a backer rod or similar device, while the preformed sealants do not. POINT OUT THE DIFFERENT CONFIGURATIONS OF THE JOINT RESERVOIR REQUIRED FOR EACH TYPE OF SEALANT. BRIEFLY DISCUSS THE REASONS FOR THE VARIOUS SHAPE FACTORS. Cold Applied Hot Applied Preformed

Surface Prep Flush joint with water to remove sawing residue Sand blast vertical faces of joint Remove sand blasting residue with oil-free air The vertical faces of the joint must be clean for the sealant to adhere Always check the air/water trap on the air compressor

Backer Rod Polyethylene foam (cold) Cross-linked polyethylene foam (hot or cold) CSS-72 The shape factor of a formed-in-place sealant is critical for optimum performance. Using a backer rod assists in controlling the proper sealant shape. Backer rods also prevent the sealant from flowing out of the bottom of the widening cut and adhering to the bottom of the reservoir. The backer rod diameter should be approximately 25 to 50% greater than the reservoir width to ensure a tight fit. Materials used for backer rods include the following: Polyethylene Foam: Polyethylene foam is a closed-cell foam that does not absorb water and is moderately compressible. Because polyethylene foam may melt with hot-applied materials, it is better suited for cold-applied sealants. Cross Linked Polyethylene Foam: Cross linked polyethylene foam is compatible with hot-applied sealants. It is a closed-cell foam that does not absorb water and is moderately compressible, but will not melt in contact with hot-applied sealant. BACKER RODS ARE VERY IMPORTANT IN ESTABLISHING THE PROPER DEPTH AND CONFIGURATION OF SEALANT. THE BACKER ROD DIAMETER IS CONTROLLED BY THE RESERVOIR WIDTH. THE DEPTH SHOULD BE ACCORDING TO THE MANUFACTURER’S RECOMMENDATIONS FOR THE SPECIFIC SEALANT.

Backer Rod Installation Handle Backer Rod Reservoir Insertion Wheel CPR-257 Figure: For most work a dual-wheeled roller is recommended. However, for rehabilitation work with slightly faulted joints, a single-wheeled roller may work better. The roller will allow you to reference insertion depth to the low side of a faulted joint. Sealant installation will then be at the appropriate depth. It also recesses the sealant enough to allow sealing the joints before diamond grinding. ENGINEERS MUST ENSURE THAT THE MINIMUM INSERTION DEPTH IS OBTAINED. THIS IS MADE POSSIBLE BY USING A ROLLER WITH THE RIGHT DIMENSIONS TO MATCH LOCAL SPECIFICATIONS AND CONDITIONS.