Concrete Leveling Techniques – A Comparative Ergonomic Assessment

Abstract

Removing excess concrete and leveling concrete to grade – a.k.a. concrete screeding – can be accomplished using a number of different techniques. Five concrete screeding techniques were evaluated to characterize construction workers exposures to risk factors for developing work-related musculoskeletal disorders (WMSD). Workers were videotaped using manual, vibratory, roller, and laser screeding equipment on new construction sites. WMSD risk factors for the five screeding techniques were analyzed using the following ergonomic assessment methods: Posture, Activity, Tools, and Handling (PATH), ACGIH® Hand Activity Level TLV®, Strain Index, Washington State Ergonomic Rule, Liberty Mutual Manual Material Handling Tables and the NIOSH revised lifting equation. The most serious risks for developing musculoskeletal injuries of the upper extremity and back were observed during manual and roller screeding. Powered screeding techniques generally presented less risk than manual screeding, but these techniques can require brief periods of medium to high exertion for lifting tasks. Vibratory screed operators are exposed to hand-arm vibration, but vibration levels were not measured. Operating the walk-behind and the cab operated laser screeds presented the least risk. Suggestions are provided to limit the use of hand screeding, and to minimize potential exposure to risk factors related to operating and handling the powered screeding equipment.