ABSTRACT
This chapter provides an overview of nearly three decades of shotcrete research and development carried out in Canada by graduate students at Université Laval in Quebec and at the University of British Columbia. Some of the findings from this academic research and development work have had a profound influence on advances in shotcrete technology in North America and around the world. A good example of this is the use of the high initial air content concept to enhance the pumpability and shootability characteristics of wet-mix shotcrete. Other notable research projects include use of microfibres to mitigate plastic shrinkage cracking; use of air entrainment to mitigate deicer chemical-induced scaling; study of the effects of voids around reinforcing steel on the load/slip curve in rebar bond tests; fundamental understanding of the effects of nozzle body type and nozzle tips on the shotcrete spray pattern and impacting force on the receiving surface; effects of aggregate gradations on rebound and other performance attributes of dry-mix shotcretes; effects of accelerator types and addition rates on performance of both plastic and hardened shotcretes; development of a new patented dry-mix shotcrete water-ring and nozzle tip with superior water dispersion/mixing action in the nozzle, and reduced rebound, and the ability to be used with rapid setting-materials.
