Morphology

Morphology of Hydration Products

Scanning electron microscopy is one of the best methods for studying the morphology of hydration products. Two methods are commonly used. First, backscattered electron (BE) imaging of polished sections is used whenever quantitative analysis is desired. Second, secondary electron (SE) imaging of fracture surfaces is a somewhat easier approach that yields direct images of the microstructure. An SE image can often help one understand the crystallinity of phases, and see how cracks propagate through the microstructure.

BSE of 0.4 w/c mortar showing dense CSH around unhydrated grains with less dense outer product of same grey value, field width of 115 microns (x1000). [BSE by David Lange, UIUC, and Hamlin Jennings and S.P. Shah, Northwestern University]

BSE of 0.4 w/c mortar showing dense CSH around unhydrated grains with less dense outer product of same grey value, field width of 115 microns (x1000). [BSE by David Lange, UIUC, and Hamlin Jennings and S.P. Shah, Northwestern University]

This 0.4 w/c sample was intruded with Wood's metal under high pressure (5000 psi). The bright regions are pores filled with Wood's metal. This test was performed to study how mercury intrusion porosimetry fills the microstructure. The point of interest is that the Wood's metal intruded the open "groundmass" but not the "inner product" or the unhydrated grain. (Field width of 85 microns, x1000). [BSE by Kelly Willis and David A. Lange, UIUC]

This 0.4 w/c sample was intruded with Wood’s metal under high pressure (5000 psi). The bright regions are pores filled with Wood’s metal. This test was performed to study how mercury intrusion porosimetry fills the microstructure. The point of interest is that the Wood’s metal intruded the open “groundmass” but not the “inner product” or the unhydrated grain. (Field width of 85 microns, x1000). [BSE by Kelly Willis and David A. Lange, UIUC]

Composite BEI of 7 day old mortar (L0100 and L0103) showing densification with silica fume. (Field width of each is 80 microns, x1000) [BEI by David Lange, UIUC, and Hamlin Jennings and S.P. Shah, Northwestern University]

Composite BEI of 7 day old mortar (L0100 and L0103) showing densification with silica fume. (Field width of each is 80 microns, x1000) [BEI by David Lange, UIUC, and Hamlin Jennings and S.P. Shah, Northwestern University]