MAPPING DRYING SHRINKAGE DEFORMATIONS IN CEMENT-BASED MATERIALS

A new technique for mapping the deformations in a digital image of mic rostructure is presented. This technique works on any set of two digit al images of the same area taken before and after deformations are gen erated. Results for cement paste show that the deformations are distri buted as large compactions separated by crack-like rarefactions. The r arefactions may represent the precursor to microcracking. The results suggest that macro-scale deformation is the result of a competition be tween expanding and contracting parts of the matrix. Individual microd eformations can then be much higher in magnitude than average macrodef ormations. A single shrinkage value like the average macrodeformation does not, therefore, adequately represent the microstructural processe s occurring during drying shrinkage. (C) 1997 Elsevier Science Ltd.