Happens when a harsh, under-sanded, segregated or stiffening load packs off in a reducer, elbow or hose, or when the line was not primed with slurry before the first concrete went in. The crew stops, relieves the pressure, finds the plug by tapping along the line and listening, and breaks the coupling to clean it out. Opening a line that is still under pressure is one of the most dangerous moves on a pump job.
Got a plug at the reducer, shut it down, relieve the pressure and nobody touches a clamp until I say.
Also heard as
- pack-off
- blockage
- plugged line
Related terms
Boom pump
A truck-mounted concrete pump with a folding hydraulic boom that places concrete right where it is needed.
Slick line
Rigid steel pipeline that carries pumped concrete from the pump to a distant or elevated pour area.
Hot load
A truckload of concrete that is setting faster than it should, from heat, delay or leftover concrete in the drum.
Segregation
Separation of coarse aggregate from the mortar in fresh concrete, leaving rock-heavy and paste-heavy zones.