European trends strongly influence American practices. The trend toward tighter jobsite controls is shown in the consolidation of the numerous, separate European countries' codes into one unified set of codes for all Common Market countries. ENV 206 Concrete—Performance, Production, Placing and Compliance Criteria will be the Eurocode that applies to all countries in Europe, leading toward greater uniformity in concrete construction.These new specifications will require producers and contractors to guarantee quality standards.
Many European producers have found that combining transit-mix plants with trucks using high-efficiency mixing drums affords the best means of achieving an exact and homogeneous mix that will meet or exceed the specifications. Preloading a truck long before it leaves the plant, combined with using a truck that has enhanced monitoring equipment on board, is the best way to obtain concrete that meets or exceeds the specifications.
There are two basic types of high-performance trucks. One uses a normal drum with a more effective fin and increased water input. The other drum design uses special features to speed the mixing rate, such as a second spiral inside the normal spiral turning in the opposite direction, or an additional vibrator inside the drum to loosen the mixture.
The most effective of these mixers requires only three to five minutes to adequately mix a load of concrete. Some have computer-controlled systems that allow the truck to download data from the batch plant wirelessly and print out the specifications onsite.
Another option that can be used in conjunction with mixing concrete in the truck onsite is preloading materials in layers before transit.
The article also lists technological, production and mechanical reasons for European producers' move toward high-efficiency mixer trucks as well as some other European production trends.
Keywords: Europe, transit mix, dry mix