Processing and Properties of Chemically Derived Calcium Silicate Cements.

摘要

Chemical engineering approach has been employed to promote elimination of large size flaws and improve strength. A general philosophy in the program was to prepare advanced cements designated as chemically bonded ceramics and use fracture mechanics and fractography to determine the size and origin of the critical flaw. Flaws of a certain type were eliminated in subsequent materials by alteration in some stage of the processing scheme. One of the most important goals of the current program was to analyze the effectiveness of indentation techniques for evaluating the mechanical properties of cementitious materials. The indentation-strength technique was found applicable to MDF cements for measuring fracture toughness. The indentation-strength technique and fracture surface analysis were found applicable MDF cements for measuring fracture toughness. By using both optical and electron microscopes, fractograph becomes a powerful tool to estimate the toughness. Therefore we suggest the small crack techniques are applicable for the measurement of crack growth resistance in cementitious materials as long as the crack size is a characteristic dimension of the microstructure.