Analysis of the development of cluster cracks in the cement paste modified by microsilica

Article describes the course of research on the possibility of the application of the computer-based image analysis techniques to evaluate the structure of cluster cracks on the surface of modified cement paste. Four sets of specimens were performed, based on two Portland cements (CEM I 42,5R and CEM I 52,5R). In addition, the two series include microsilica as a substitute for 10% of cement. Cracks of samples were obtained by the sudden temperature load at the value of 250°C. Image of the cracked surface was obtained by scanning at a resolution of 2400DPI, and to digital processing and measurements ImageJ v. 1.46r software was used. To describe the structure of the cracks two stereological parameters were proposed: average cluster area (A) and average cluster perimeter (L). The aim of the work is to reference obtained results from the image analysis to the compressive and tensile strength of tested specimens. In addition, considering the structure of cement paste as a dispersion system the process of the cluster structures formation was described, which under external loads transform and affect the final properties of the composite material.