AS2251 and AS2301 Screeds Caterpillar

Troubleshooting the Mat

Problems in obtaining the correct mat surface finish can be traced to several different sources.

The problem is short waves in the surface.

The probable cause may be listed below.

• The mix temperature is inconsistent.

• The mix is separating.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

• The rolling operation is not correct.

• The base is not properly prepared.

• The grade reference is not correct.

• The grade control wand is bouncing on the reference.

• The sensitivity is set too high for the grade control.

• The grade control is not mounted correctly.

• The screed plates are not tight.

• The screed is riding on the lift cylinders.

• There is excessive play in the mechanical connection for the screed.

• The paver speed is too fast.

• The augers are overloaded.

• The head of material fluctuates.

The problem is long waves in the surface.

The probable cause may be listed below.

• The mix temperature is inconsistent.

• The mix is separating.

• The base is not properly prepared.

• The truck brakes are being held.

• The truck is bumping the machine.

• The machine is sitting for long periods of time between loads.

• The grade reference is not correct.

• The grade control is not mounted correctly.

• The asphalt feeders are not set properly.

• The hopper is emptying between loads.

• The screed is riding on the lift cylinders.

• The screed reaction time is not correct when you adjust the thickness control.

• There is excessive play in the mechanical connection for the screed.

• The augers are overloaded.

• The head of material changes.

The problem is tearing of the mat across the entire mat.

The probable cause may be listed below.

• The mix temperature is cold.

• The mix temperature is inconsistent.

• There is moisture in the mix.

• The mix is separating.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

• The thickness of the mat is incorrect for the maximum size of the aggregate.

• The screed plates are cold.

• The screed plates are worn out or warped.

• The machine is moving too fast.

The problem is tearing of the mat in the middle.

The probable cause may be listed below.

• The asphalt mix is cold.

• The kicker screws are worn out.

• The kicker screws are mounted incorrectly.

• The screed plates are cold.

• The screed plates are worn out or warped.

• There is not enough lead crown in the screed.

The problem is tearing of the mat on the ends.

The probable cause may be listed below.

• The asphalt mix is cold.

• The screed extensions are installed incorrectly.

• The asphalt feeders are not set properly.

• The mold board on the strike off is too low.

• The screed plates are cold.

• The screed plates are worn out or warped.

• There is too much lead crown in the screed.

The problem is the texture of the mat that is not uniform.

The probable cause may be listed below.

• The asphalt mix is cold.

• The temperature of the asphalt mix is inconsistent.

• The asphalt mix is improperly designed.

• The mix is separating.

• The base is not properly prepared.

• The asphalt feeders are not set properly.

• The thickness of the mat is incorrect for the maximum size of the aggregate.

• The hopper is emptying between loads.

• The machine is sitting for long periods of time between loads.

• The vibrator is too slow.

• The screed extensions are improperly installed.

• The screed is riding on the lift cylinders.

• The machine is moving too fast.

• The augers are overloaded.

• The head of material fluctuates.

The problem is marks in the mat that are left by the screed.

The probable cause may be listed below.

• The truck brakes are being held.

• The truck is bumping the machine.

• There is excessive play in the mechanical connection for the screed.

The problem is a correction that is made, and the screed does not respond.

The probable cause may be listed below.

• The asphalt mix is cold.

• The temperature of the asphalt mix is inconsistent.

• The thickness of the mat is incorrect for the maximum size of the aggregate.

• The grade control is not mounted properly.

• The screed plates are not tight.

• The screed is riding on the lift cylinders.

• There is excessive play in the mechanical connection for the screed.

• The machine is moving too fast.

The problem is auger phantoms in the mat.

The probable cause may be listed below.

• The mix is separating.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

• The augers are overloaded.

• The augers are too low.

The problem is poor pre-compaction.

The probable cause may be listed below.

• The asphalt mix is cold.

• The base is not properly prepared.

• The thickness of the mat is incorrect for the maximum size of the aggregate.

• The vibrator is too slow.

• The screed is riding on the lift cylinders.

• The machine is moving too fast.

The problem is a poor longitudinal joint.

The probable cause may be listed below.

• The mix temperature is inconsistent.

• The mix is separating.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

• The rolling operation is not correct.

• The overlap of the joint is not correct.

• The grade reference is not correct.

• The grade control wand is bouncing on the reference.

• The sensitivity is set too high for the grade control.

• The grade control is not mounted correctly.

• The screed is riding on the lift cylinders.

• The screed reaction time is not correct when you adjust the thickness control.

• The augers are overloaded.

• The head of material changes.

The problem is a poor transverse joint.

The probable cause may be listed below.

• The asphalt mix is cold.

• The rolling operation is not correct.

• The starting blocks for the screed are too short.

• The null for the screed is incorrect.

• The screed plates are not tight.

• The screed is riding on the lift cylinders.

• There is excessive play in the mechanical connection of the screed.

• The augers are overloaded.

The problem is cracking of the transverse joint.

The probable cause may be listed below.

• The temperature of the asphalt mix is inconsistent.

• There is moisture in the asphalt mix.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

• The rolling operation is not correct.

• The base is not properly prepared.

The problem is mat shoving under the roller.

The probable cause may be listed below.

• The temperature of the mat is inconsistent.

• There is moisture in the mix.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

• The rolling operation is not correct.

• The base is not properly prepared.

The problem is bleeding or flat spots in the mat.

The probable cause may be listed below.

• The temperature of the asphalt mix is inconsistent.

• There is moisture in the mix.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

The problem is marks from the roller on the mat.

The probable cause may be listed below.

• The temperature of the asphalt mix is inconsistent.

• The rolling operation is not correct.

• The base is not properly prepared.

The compaction of the asphalt mix is poor.

• The temperature of the asphalt mix is inconsistent.

• The asphalt mix is cold.

• There is moisture in the mix.

• The design of the asphalt mix is not correct.

• The design of the aggregate mix is not correct.

• The base is not properly prepared.