CALCIUM HYDROXIDE IN CEMENT PASTE AND CONCRETE - A MICROSTRUCTURAL APPRAISAL

摘要

The microstructural role of calcium hydroxide (CH) in cement paste and concrete is reviewed. A number of backscatter SEM micrographs are used to provide illustrations of typical appearances and configurations of CH particles in hydrated cement paste. Image analysis assessments of CH contents in cement paste are illustrated, and the results are shown to be comparable to CH contents of similar pastes determined by DTA. The results of quantitative measurements of the size distributions of CH particles in cement paste, as determined by image analysis, are provided. Determinations of several particle shape parameters for CH particles in cement paste are illustrated. Differences between CH in cement paste and CH in concrete are discussed. The presence of CH deposits on some of the surfaces of sand and coarse aggregate grains and around air voids are illustrated. The vulnerability of the CH deposits on aggregate surfaces to dissolution in permeable concretes is discussed, and possible effects of such dissolution noted.