The Use of Steel Fiber-Reinforced Shotcrete for the Support of Mine Openings

What separates the support of mining open­ings from the support of similar civil engineering structures is the fact that mine openings have to survive large defonnations as a result of changing stress conditions induced by progressive mining. Steel fibers impart to concrete and shotcrete a high degree of ductility which not only allows the shotcrete and concrete linings to absorb important rock movements, but also to increase their bearing capacity by a redistribution of the loads.
The use of shotcrete for the support of under­ground excavations was pioneered by the civil engineering industry. In recent years, the mining industry ha,;; become a major user of shotcrete for underground support. The simultaneous working

Steel Fiber Reinforced Shotcrete, It is time to find out about it.

In an age when the building, tunneling, and in some areas, min­ing industry, is thriving in North America, we in the shotcrete industry should be looking for ways to increase productivity and save on ever-increasing labor costs. This type of thinking often requires the use of products that we either are not familiar with or have never used at all. Since we are in an industry where our chief concerns are keeping a safe workplace, while at the same time, trying to increase production or speeding up project comple­tion time, we are often times unwilling to try new technology because we are afraid of the unknown. We fear a decrease in pro­duction, having to buy new equipment, and worst of all, lost­time accidents.For this reason-the unknown-many shotcrete contractors and mine managers have shied away from the use of steel fibers in their shotcrete. Their arguments against using steel fibers are often the same. “We use mesh or rebar for reinforcement because we know for sure that the reinforcement is in place before we apply shotcrete. That way, we don’t have to worry whether or not we have added the correct amount of steel fibers, or if the steel fibers are mixed uniformly, or if the fibers will do the job at all.” Or, we hear the all too familiar response, “If it is not broken, don’t fix it.”
In my opinion, this “if it is not broken, don’t fix it” attitude is keeping a lot of shotcrete contractors from increased production and greater financial successes. Sure, the economy in North America is strong now in the

Big Bad Curves?, Pumping Fiber-Reinforced Wet-Mix Shotcrete

Making good pumpable concrete or wet­ mix shotcrete is not always easy, especially
when fibers are present Adding fibers to ordinary wet-mix shotcrete sometimes re­
results in nonpalpable or difficult-to-pump concrete. Simply adding superplasticizer 10 fiber-reinforced shotcrete does not always result in a workable mixture.

Evolution of Fiber Reinforced Shotcrete

The concept of reinforcing shotcrete with discrete, disominous steel fibers was developed by the Battelle Research Corporation in the USA in the early 1970s.

Shotcrete Rehabilitation of a Vancouver, BC Historic

A heritage high-rise building in Vancouver, Canada required rehabilitation due to corro­sion of the steel frame and cracking in the masonry infill. Brick masonry was segmentally removed from the face of this 15-story-high building to expose the steel beam and column framjng system. Steel corrosion products were removed by needle scaling and sandblasting. New steel plate was welded to the beams and columns where required to strengthen the structure to its original design. Rebar was installed in the previously brick-filled cover to the steel frame and a high quality, low permeability silica fume shotcrete was applied to encase the rebar and fill the void. The south side of the building was

Seismic Reinforcing of Masonry Walls With Shotcrete

Photos and newsclips show­ing hundreds of collapsed homes bury­ing entire families have become all too commonplace. As residents of North America we are thankful that this sort of calamity doesn’t happen here. The earth­quakes we’re used to seeing (mainly in California) cause inconvenience and in some cases property damage, injury and even some deaths, but nothing as cata­strophic as in Turkey this year and Azerbaydzhan a few years back.