The pigments may be added at the concrete mixer. Primarily a vocational straight truck they are often used as dump and concrete mixer trucks. Connolly retained Melvin Belli as counsel and sued the concrete mixer company. This breakwater work may also have been the site of the world's first concrete mixer. However, silica fume is more usually added to Portland cement at the concrete mixer. A typical concrete mixer uses a revolving drum to mix the components. On Umnak Island, a concrete mixer and some docks were lost. The concrete mixer was invented by Columbus, Ohio industrialist Gebhardt Jaeger. A typical portable concrete mixer uses a small revolving drum to mix the components.