Imaging techniques applied to quality control of civil manufactured goods obtained starting from ready to use mixtures

Concrete materials obtained from the utilization of pre-mixed and ready to use products (central mix-concrete) are more and more used. They represent a big portion of the civil construction market. Such products are used at different scale, ranging from small scale works, as those commonly realized inside and house, an apartment, etc. or at big civil or industrial scale works. In both cases the problem to control the mixtures and the final work is usually realized through the analysis of properly collected samples. Through appropriate sampling it can be derived objective parameters, as size class distribution and composition of the constituting particulate matter, or mechanical characteristics of the sample itself. An important parameter not considered by the previous mentioned approach is "segregation", that is the possibility that some particulate materials migrate preferentially in some zones of the mixtures and/or of the final product. Such a behavior dramatically influences the quality of the product and of the final manufactured good. Actually this behavior is only studied adopting a human based visual approach. Not repeatable analytical procedures or quantitative data processing exist. In this paper a procedure fully based on image processing techniques is described and applied. Results are presented and analyzed with reference to industrial products. A comparison is also made between the new proposed digital imaging based techniques and the analyses usually carried out at industrial laboratory scale for standard quality control.