February 26, 2021
T. Mäkelä Oy, a Finnish contractor based in Jyväskylä, got a demolition contract to tear down a four floor concrete block building in Central Finland. The schedule was tight as well as contract amount was challenging. The apartment building was built using 12 mm steel rebar reinforced concrete – all together more than 3000 tons of concrete material.
The first stage was to tear down the building using concrete pulverizers to app 400-500 mm size, biggest concrete blocks being size 800 x 400 x 250 mm after pulverizing.
Two excavators were used to precut the blocks. The smaller excavator Hitachi Zaxis 280 LC was used to crush the concrete blocks to 0-80 mm size fragmentation. During the pulverizing process manually sprayed water mist reduced the dust, because of the nearby housing.
The second stage was to crush large concrete blocks to fragmentation size 0-80 mm, to be reused in road foundation construction. Crushing the concrete and reusing the material brought considerable savings compared to haul the material to the landfill tip. Majority of the transportation and all the waste material fees were eliminated. As a matter of fact the 0-80 mm crushed concrete material reused represented good amount of income.
“Instead of traditional crushers we used Viper slow moving drum crushing bucket to crush the concrete. We have experience of the jaw crushers but we selected the Viper VPCH 21 crushing bucket because a number of reasons. Superb capacity and no daily maintenance helped us a lot to keep the tight schedule” tells Mr. Tatu Kantola, operator of the Viper crushing bucket.
Viper VPCH 21 is a one drum crushing bucket. The slow moving, 40 rpm, large 700 mm drum with hard metal tips crushes the material against the counter teeth. Using the bottom grid Viper crusher is able to reduce the fragmentation from standard 0-150 mm down to min 0-60 mm.
The larger VPCV 22 is a two drum crusher bucket, in which the drums rotate opposite direction crushing the material between the drums.
The crushing capacity of VPCH 21 was app. 94 tons/h, which is about double compared to conventional crusher buckets. The 12 mm rebar just dropped through the bucket and did not cause any delays. In rare cases when the steel bar bent around the tooth it was easy to lose it just counter rotating the drum. The dust was not such a problem as when using the pulverizers. Additional Viper high pressure water dust suppression system was not needed in this job site.
“In addition to the dust, noise is frequently an issue in cities and populated areas. Viper crushing buckets are really silent compared to jaw crushers” tells Mr. Tatu Kantola and continues “Viper bucket is fast and easy to use and crush even large blocks in one stage – it’s almost like a normal digging bucket with large opening and fast to fill”
All Viper drum crusher buckets are able to crush hard demolition materials, such as concrete and tiles. Frequently soft, elastic and fine materials cause capacity problems when using traditional crushers. Viper drum crusher is effective in mixed materials, too. Asphalt, tarmac, fine material, wood and mixed waste does not cause any jamming or capacity constraints as many other methods do.