An electron-microscope study of the contact between aggregate and hardened cement paste

Two variations of a method of making two-stage replicas have been developed for studying in the first instance the contact between aggregate and hardened cement paste. The method, known as the impression method, requires about 15 min to make one replica without destruction of the specimen. The study was made on ‘model’ concrete (which is described) to eliminate the effect of impurities and sand. The principal aim of the paper is to give information on the newly developed method but, in addition, an attempt is made to give a morphological interpretation of the contact phenomena and to discuss certain difficulties complicating this kind of study.