Determination of the proportion of anhydrous cement using SEM image analysis

•SEM image analysis was used to determine the proportion of anhydrous cement in materials.•A specific MATLAB program was developed for SEM image analysis.•Reactive characteristics of powder by-products were determined with isothermal calorimetry.•Significant mechanical properties have been measured on standard mortars with by-products.

The proportion of anhydrous cement in materials is essential data in relation to reactivity potential, particularly in by-products that may be reused it in concrete techniques. This paper presents a method based on Scanning Electron Microscopy (SEM) image analysis and a specific program in Matlab that was developed to statistically determine the proportion of anhydrous cement. Industrial by-products containing anhydrous cement were tested by this method and a percentage of around 15-20% was found in the analyzed by-products. The reliability of these results is noteworthy in comparison with those given by classical image analysis software. The reactive characteristic and the hydration kinetics of the analyzed by-products were also verified using isothermal calorimetry and a mechanical study of standard mortars in which the cement had been partially replaced by these by-products.