Imaging techniques applied to quality controlof concrete materials obtained from the utilisation of pre-mixed ready to use products

The utilization of mixtures mainly composed of cement, gravel, water and, sometimes, specific additives represent a common practice in the civil construction sector. Such mixtures originate what is usually and simply called “concrete”. Different concrete types can be realised according to a different utilisation of the different constituting materials, both in terms of single component characteristics and their relative amount. As a consequence the quality control process of the different phases, allowing to realise a concrete of the desired quality, represents one of the fundamental steps in the production process. To control concrete quality a lot of well established and reliable measuring control methods exist. They are finalised to physically, or chemically, evaluate specific attributes of the constituting and/or the final set materials. The adopted approaches do not allow to correctly identify and quantify an important phenomena whose entity can prejudiced the final quality of concrete, in terms of mechanical strength, insulating property, aesthetic attributes, etc., that is “segregation”. Such a term is referred to the possibility that during setting, specific phenomena, related to particulate solids fractions characteristics, occur, causing the production of a concrete of not homogeneous mass characteristics. In this paper an attempt to define a set of procedures to fully characterise and quantify segregation adopting an imaging based logic is presented, analysed and discussed with reference to industrial pre-mixed and ready to use concrete. A comparison is also made between the proposed imaging based techniques and the analyses usually carried out, at industrial laboratory scale, for standard quality control.