Sagging Slats - A Safety Hazard
The Problem
Over the last ten years , a number of failures of cattle slats, some of which resulted in the loss of animals, have been reported. The main concern is in relation to floors comstructed using single or twin rib slats.
The problem arises because the environment in which slatted flooring is used is extremely aggressive due to the effect of the different chemicals in animal waste. These can corrode the reinforcing effect of the different chemiclas in animal waste. Theses can corrode the reinforcing bars (within the slats) which give the slats their structural strength.
Corrosion causes spalling of the concrete around the reinforcing bars and a reduction in the effective size of the bars. This can lead to slat failure. Corrosion is a complex process and the rate at which it takes place varies and cannot be predicted with much confidence.
New Standard
- In 1993 the standard for the manufacture of slats was modified to require significantly greater concrete cover to the reinfocing bars, a higher grade of concrete and increased loading requirements.
- Although the bridge-like construction of gang slat units reduces the risk of collapse, they too should be monitored over time.
- Slats manufactured prior to 1993 require particular attention.
Inspection
Ongoing
- Be aware of any damage, cracking or loss of concrete on slats
- Note in particular diofferences in the dgree of flexing between slats.
Annual
- Thoroghly clean floor, examine entire floor for cracking, rust staining and spalling of concrete.
- Spalling of concrete is most likely to occur on the underside of the slat.
Assuming the slats were laid evenly in the first instance, the laying of a straight edge across the entre of the slats will indicate which slats have sagged. Suspect slats should be lifted, powerwashed and examined for cracks.Shallow, fine hairline cracks are not a fault.
What To Do
- Failure can occur without warning so when in doubt replace slats where problems are indicated or suspected.
- Never drive on slats with tractors or machinery unless they have been designed for the purpose.
Think Safety and Take Action
- Check old slats for evidence of sagging
- Slats with marked signs of deflection, cracking, spaling or rust staining should be replaced.
- Replace slats to the Irish Standard Specification: I.S. 249, 1993
- Properely placed slats should be level,evenly spaced and free from rocking movement.
