Architectural stone education in Verona

The articles in our series entitled, “Creating Architectural Stonework,” are a reflection of the Veronafiere-AIA Continuing Education Seminar at Marmomacc 2005 in Verona, Italy. During the first day of this session, architects were shown all of the steps taken to create the stonework for the new Banco Popolare project in Verona (pictured on the right). The education session combined classroom seminars and site visits on the processing of stone and specific architectural applications.

The eighth edition of this educational program, which is sponsored by Stone World, will once again take place at this year's edition of Marmomacc. Industry education begins on October 3, and the show itself takes place from October 4 to 7.

In the Valpolicella wine-making region of Italy, just outside of Verona, Cave Bonaldi extracts Rosso Verona marble nearly 2,000 feet above sea level. The vast quarry site produces 15 to 20 commercial stones, including the “Nembro” variety, which was used for the Banco Popolare project.

Because the stone has a high compressive strength, it is well suited for architectural exteriors, such as Banco Popolare, Cave Bonaldi reports.

Since the site is a sedimentary quarry - it was originally formed underwater - clear fossilization can be seen in many of the stone pieces. The color of the stone is derived from its oxidation, and the different natural formation processes resulted in shades of cream, red and yellow. The combinations of these shades are classified as different varieties of Rosso Verona.

During the extraction process, Cave Bonaldi avoids blasting whenever possible. It is used only for the top layers, and for separating large blocks from the quarry face - a process that also involved drilling. Before these large blocks are freed, a bed of rubble is arranged to break their fall, thus minimizing impact and fracturing. Once the larger blocks are extracted, they are further broken into smaller blocks that can be shipped for processing.

Vertical cutting in the quarry is done using diamond wire saws from Pellegrini and Marini-Quarries Group of Italy. A typical block measures 4 x 8 x 4 feet in size, and blocks are trimmed and squared to their final dimensions as needed on a stationary Pellegrini diamond wire saw. The largest blocks are used for cutting into slabs, while the smaller blocks can be used for tile and cut-to-size production. The company once produced a 44-ton block, but the size limit is not the geology of the quarry, but transportation. In addition to standard blocks, Cave Bonaldi can extract atypical shapes for specific architectural pieces, such as large columns.

The quarry site itself is quite large, and crews work different sections depending on consumer demand for the different varieties. At the present time, the company is extracting stone from a “bench” measuring around 16 feet high that it reports to be some of the best material ever taken from the quarry. Although the bedding plane is inclined, it only presents a minimal challenge, due to the experience of the crew.

The areas for extraction are not always adjacent to one another, and after a section of the quarry is closed to further work, it is re-claimed by filling it in with dirt, which allows agriculture to grow and preserves the beauty of the landscape for future generations.