Failure to comply with the standard NP EN 206-1 [1], which recently replaced the NP ENV 206 [2], and the no quality and no conformity of concrete, catalyze the emergence of pathologies at structures, and consequently the level of finishes and masonry, reaching a premature degradation of the buildings concerned. This failure in relation to the norm, it came from the ignorance or relaxation, but also sometimes in order to save material and to increase their final profit. The main objectives of this study were to characterize the procedures adopted for the production of concrete in some works in the district of Braga, determining the strength class of concrete produced in these works and the comparison with the resistance required in the project. At this point, we proceeded to evaluate the strength of concrete in situ and comparison with the resistance obtained in the works under study. It was compared the evaluation of concrete strength by the standards of Portugal (Europe), with the United States of America. It was also followed a period of production of concrete in a central production of the District of Braga. In the end, there were proposals that will improve the quality of concrete. It was found that in comparison with the previous NP ENV 206 [2], the new standard NP EN 206-1 [1] is more demanding with the producers and the concrete without certification of production control. The U.S. rules are more demanding in the sampling plan and assign a classification to the collection of samples. In this mater, there was founded a great lack of training for workers who deal closely with the process. Whatever the standard used, we can say that when the inspection is broader, faster and tighter, better we can control and correct at time the quality of concrete used. It is important a proper awareness and training of persons involved in this matter.