Presently, the characteristics of pavers are evaluated with the help of DIN norms. Thus, in Germany we have the norms DIN 1338 for paving stones and the DIN 1339 for paving slabs to determine the quality features of the finished product. To meet the requirements, the aggregates –sands, cement and fly ashes- are adjusted optimally, so that the demands from the norm are fulfilled with as little as possible effort.
Only optimally adjusted products make it possible to stay competitive in the hard-fought market. Producers of machines and mixing equipment have done a lot during the past years to manufacture concrete mixes as reproducible as possible.
Despite the high level of development within production technology there is no standard quality control of the finished product. Currently substantial decisions about changes for coming mixtures and machine settings are subjectively made by the operator with the help of height and weight determination. Unfortunately “subjectively” often means that one and the same case is evaluated differently. Problems at the finished product are often recognized very late or not at all, in the worst case. High scrap rates and the inadequate use of resources is the consequence.