Shotcreting in Australian Underground Mines: A Decade of Rapid Improvement

Over the last decade, dramatic improvements in spraying technology have allowed shot-crete to become the first-choice ground support in many underground mines in Australia. Before 1994, only a very small amount of dry spray shotcrete was used. Since then, the increased use of wet-mix fiber-reinforced shotcrete has been extremely rapid, spurred along by improvements in machinery, admixtures, fibers, and under-standing the way shotcrete behaves as a ground support element.
Today, nearly 100,000 m3 (130,000 yd3) of shotcrete is applied annually in some 20 under-ground mines. While volumes have leveled off during a recent period of depressed metal prices, it is almost certain to boom again as metal prices improve and new mines come online. Australian mines are characterized by reasonably shallow ore bodies hosted in hard rock. This made under-ground mining initially fairly simple with little ground support needed beyond a few rock bolts. As surface deposits have become depleted, however, mine owners are increasingly spending their exploration dollars drilling beneath existing deposits to find new resources. This has led to ever-deepening extraction depths and associated ground support difficulties.

Artistic Shotcrete for a Historic Auditorium

The Goetheanum (Fig. 1) in Dornach, near Basel, Switzerland, was constructed in the late 1920s from a design by Austrian social philosopher and œspiritual scientist Rudolf Steiner. This building represents the first use of reinforced concrete for monumental, sculptured forms.

Shotcrete Meets the Challenge of Huge Water Project in Ecuador

Shotcrete Meets the Challenge of Huge Water Project in Ecuador replacing traditional œform-and-pour reinforced concrete construction methods with high-production shotcrete, the massive Trasvases Manabi Water Project in Ecuador was finished months ahead of schedule. Contractor Norberto Odebrecht, in conjunction with Shotcrete Technologies, Inc., of Idaho Springs, Colorado; and Commercial Shotcrete, Inc., of Higley, Arizona, placed over 6000 m3 (7800 yd3) of shotcrete in less than half the time it would have taken by the specified œform-and-pour method. They put the project an entire rainy season (approximately four months) ahead of schedule.

Application and Testing of Shotcrete

In 1989, the Austrian Concrete Society pub-lished a Guideline on Shotcrete that subse-quently served as a reference work and a contractual basis for shotcrete works in tunnel con-struction in Austria and abroad. Other standards,such as DIN 18551, focused more strongly on shotcrete for concrete repair works. At the end of 1998, after several revisions, a new edition of the Austrian Guideline was published that also con-siders recent developments in the field of shot-crete technology. Dealing with a
whole range of issues, from base ma-

Shotcrete Red Hot in Peru

An1amina copper mine is a Sl.2 btltion projcc1 in lhe Andes Mountailh of Peru. The projeci. owned by Canadian mining gi3111S Norandll. J’cck and Rio Afgom, i.s one of the. single largest mining inveso:nents in 1be Americ:iô€€£ at this moment and oomprises the cons1ruction of an open pi1, a co11veyor runnel, a tailings dam. a mill and pon facilities for ¢1’por1 of processed concenlrllle all over the globe.

Round Determinate Panel Testing in Australia

Designers and contractors frequently encounter difficulties when using beams for the assessment of postcrack pcrfomumcc in fiber­reinforced shotcrcte (FRS). llie most conimon bea,n test used in Nonh Anierica is the ASTM C-1018 procedure (AST!vl 1997), although alternatives exist, including the Japanese SF-4 procedure (JSCE 1984) and a multi rude of European national standards.