Alternatives to lifting concrete masonry blocks onto rebar: biomechanical and perceptual evaluations

Abstract

This study examined the use of and barriers to H-block and high lift grouting, two alternatives to lifting concrete masonry blocks onto vertical rebar. Peak and cumulative shoulder motions were evaluated, as well as adoption barriers: H-block cost and stakeholder perceptions. Results indicated that using the alternatives significantly decreased peak shoulder flexion (p < 0.001). A case study indicated that building cost was higher with H-block, but the difference was less than 2% of the total cost. Contractors and specifiers reported important differences in perceptions, work norms, and material use and practices. For example, 48% of specifiers reported that use of high lift grouting was the contractor's choice, while 28% of contractors thought it must be specified. Use of H-block or high-lift grouting should be considered as methods to reduce awkward upper extremity postures. Cost and stakeholders’ other perceptions present barriers that are important considerations when developing diffusion strategies for these alternatives.

Practitioner Summary: This study provides information from several perspectives about ergonomic controls for a high risk bricklaying task, which will benefit occupational safety experts, health professionals and ergonomists. It adds to the understanding of shoulder stresses, material cost and stakeholder perceptions that will contribute to developing effective diffusion strategies.

Keywords:

• ergonomics
• bricklaying
• shoulder injury
• stakeholder perceptions
• biomechanics
• diffusion of innovation

Acknowledgements

This project was funded by CPWR, the Centre for Construction Research and Training (NIOSH/DHHS Cooperative Agreement 1U54 OH008307-01). The authors give special thanks to Mr. Terry Hays and Mr. Lee West from the International Masonry Institute, Western Washington Training Centre, Seattle, WA, for their technical assistance and for allowing us to collect data at the training centre. Thanks to Dr Steve Goldrick and Mr. Jeff Gau for data analysis assistance and to Mr. Steve Gunn for cost estimations. We also thank all the bricklayers who participated in this study.