1. The driver sent the wrong job site.
The driver of a mixer truck loaded C25 concrete and sent it to another site C30.
Cause analysis: When the driver fills out the vehicle tracking form, he fails to see the site name and the construction unit, and the work is careless.
Corrective measures: Each concrete mixer truck must be clearly marked with the strength level. After the concrete is loaded, the driver should fill in the project name and construction unit on the vehicle tracking form in time to avoid sending to the wrong construction site. The dispatching center should pay close attention to the operation of the GPS satellite positioning system vehicles, and promptly correct any problems found.
2. Water in the driver's transporter drum.
When a driver loads concrete, the slump of the accumulated water in the drum is too large.
Cause analysis: After loading and washing the pump water in the previous car, it did not run out when it reached the construction site, but the remaining water in the drum was not discharged in time, and it was charged without confirmation.
Corrective measures: The dispatching center must control the mixer truck that is used to wash and wash the pump truck water, and then notify the loading after receiving the driver's discharge confirmation. After the driver has washed the car and after the rainstorm, the accumulated water in the drum must be removed.
3. Leaking and caking.
1) On a certain day when the driver was transporting concrete to the construction site, the drum was reversed and leaked, which caused a large area of road pollution.
Cause analysis: The anti-reverse pin was not inserted before loading the vehicle, causing material leakage.
Corrective measures: It is required that the driver of the mixer truck must check whether the anti-reverse pin is inserted before loading the truck.
2) On a certain day, the driver of the mixer truck transported the C40 concrete at a construction site. After the unloading, the concrete was not checked for unloading. The empty truck was weighed and the empty weight was not checked.
Analysis of reasons: The driver of the mixer truck was careless in his work and did not check the concrete unloading in the drum according to the prescribed procedures.
Corrective measures: Strengthen the quality awareness training of the mixer truck driver. After unloading, check whether there is material accumulation in the drum. The Ministry of Transport periodically checks the weight of the empty truck back to the factory to avoid mixing the leftover materials with concrete of different strength levels.
3) One day the screw of the reducer of the mixer truck breaks, the drum cannot rotate, causing the concrete to condense in the drum.
Cause analysis: The screw of the reducer is broken, which makes the drum unable to rotate.
Corrective measures: The driver of the mixer truck should perform daily vehicle inspections, and focus on checking whether the screws of the drum reducer are tightened or have bends and cracks, so as to avoid screw breakage during high-speed rotation and cause concrete scrap.
4. Pumping burst tube is blocked.
1) After the pumping of concrete at a construction site is completed, the concrete pipes are cleaned by air washing. Due to the excessive pressure, the pump pipe wall ruptures, causing workers to be injured.
Cause analysis: The water volume of the self-provided water tank of the pump truck is insufficient, and the concrete cannot be washed out by water washing. The air washing method is 3 times the water washing pressure. The pipe wall at the rear is thin and cannot bear Ruptured by air washing pressure, causing concrete to fly out and hurt people.
Corrective measures: Strictly restrict the air washing method, and disable thin and old pump tubes. The number of hoses at the outlet of the pump tube cannot exceed two and the bend should not exceed 90 degrees. The pump washing water is filled and transported from the mixing station to the site by a mixer truck. Strengthen personnel safety operation training.
2) When constructing a fifteen-story column wall at a certain construction site, the water and mortar used in the pump during pumping could not be pumped out, causing all the delivered concrete to be returned.
Cause analysis: After the construction of the 14-story beam and slab, the water leakage of the cutting ring of the drag pump was serious, and the concrete could not be washed out with water. The remaining concrete and cement bags were in the pipeline.
Corrective Action: Regularly check and replace vulnerable parts such as cutting rings. When washing the pipe, the cloth rod should be folded and cleaned separately. After washing the pipe, it must be checked that the cement bag has been washed out. Before taking over, the pipe must be checked for patency.