Problems on this page:
Batch weights out of tolerance
Hits OEE: Quality
Symptoms: Batch records show cement, aggregate or water weights outside the tolerance for the mix.
Weigh hopper load cells drifting or obstructed
Check the weigh hoppers for build-up and anything touching them, and calibrate with test weights.
Discharge gates closing late, so material overshoots
Check the gate actuators and the in-flight compensation setting.
Aggregate moisture not compensated
Check the moisture probes and the water correction in the batch control.
Cement screw over-running after stop
Check the screw stop and the fine feed setting near target.
Prevention: Batch tolerance report reviewed daily.
Slump or workability varying
Hits OEE: Quality
Symptoms: Concrete leaves the plant wetter or stiffer than the mix design.
Moisture probe in the aggregate bin out of calibration
Check the moisture probe readings against oven-dried samples.
Admixture dosing pump not calibrated
Calibrate the admixture dispensers.
Mixing time too short
Check the mixing time in the recipe for the mixer type.
Aggregate grading changed
Check the grading of the delivered aggregate.
Prevention: Slump or flow tested on the first loads and at set intervals.
Cement silo blockages
Hits OEE: Availability
Symptoms: Cement stops flowing from the silo to the screw.
Cement bridging from moisture
Check the silo filter and aeration air for moisture.
Aeration pads blocked
Check the aeration system and its air supply.
Butterfly valve sticking
Service the silo outlet valve.
Silo overfilled during delivery and filter blinded
Check the high level probe and filter cleaning.
Prevention: Silo flow problems recorded with the date of the last delivery.
Mixer wear and build-up
Hits OEE: Availability
Symptoms: The mixer takes longer to discharge and concrete builds up inside.
Mixer not washed out at the end of the day
Wash out the mixer at every shift end.
Mixing arms and liners worn
Check the arm clearance to the liners and replace worn parts.
Discharge door seal worn
Replace the door seal.
Hardened build-up left
Remove build-up only with the mixer isolated and locked off; mixer entry is a confined-space and moving-parts hazard.
Prevention: Mixer condition checked weekly.
Aggregate conveyor problems
Hits OEE: Availability
Symptoms: The aggregate belt slips, runs off to one side or spills material.
Belt tension too low
Check the take-up and set the tension as the maker specifies.
Belt scrapers worn, so material builds up on pulleys
Replace worn scrapers and clean the pulleys.
Idlers seized
Replace seized idlers; they wear the belt and can run hot.
Feed from the bins too heavy or off centre
Check the bin gates so material lands in the centre of the belt.
Prevention: Belt and idlers checked daily.
Dust from cement handling
Hits OEE: Availability
Symptoms: Cement dust escapes during deliveries or batching.
Silo filter blinded
Clean or replace the silo filter elements and check the cleaning pulses.
Weigh hopper vent blocked or missing
Check the vent and its filter on the cement weigh hopper.
Mixer inlet seal worn
Replace the seal between the cement hopper and the mixer.
Delivery blown in at too high a pressure
Agree the blowing pressure with the haulier and watch the silo pressure relief.
Prevention: Dust checked at each cement delivery.
Batch control faults
Hits OEE: Availability
Symptoms: The batch control system stops batches with faults.
Weighing or moisture sensor fault
Check the sensor reading and its cable.
Gate limit switch not proving closed
Check the gate limit switches and their targets.
Communication to the loading office lost
Check the network link and restart in the order the supplier gives.
Recipe data wrong
Check the mix design data in the system against the approved mix.
Prevention: Control faults logged by type.
Water metering wrong
Hits OEE: Quality
Symptoms: The water added to the mix differs from the batch record.
Water meter worn or fouled
Check the meter against a timed volume and clean or replace it.
Water valve leaking after it closes
Check the valve for passing water.
Recycled water with high solids
Check the density of recycled water and correct the mix for it.
Air in the water line
Vent the line and check for air drawn in at the pump.
Prevention: Water meter checked monthly.
Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.
Related equipment guides: silo / hopper · screw conveyor · belt weigher · conveyor · dust collector · concrete block machine
Stop the same fault coming back
Recurring concrete batching plant stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.
Book a Fabrico demo
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Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary
Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover