Title: Microstructural Alterations of Cement Paste/Steel Interface Exposed to Sea Water

Author(s): B. Marchese

Publication: Symposium Paper

Volume: 100

Issue:

Appears on pages(s): 1611-1632

Keywords: blast furnace slag; cement pastes; corrosion; microstructure; portland cements; portland slag cements; reinforcing steels; seawater; x-ray diffraction; Materials Research

DOI: 10.14359/2183

Date: 4/1/1987

Abstract:
Microstructural modifications of steel-reinforced blast furnace slag cement and SC pastes held three years in static seawater at cement paste/steel interfaces were examined. No macroscopical alterations of pre-existing cracks have been evidenced. Aragonite patinas on steel and brass surfaces, and calcite with traces of aragonite on cement paste surface by x-ray diffraction analysis were detected. At steel/cement past interfacial region morphologies of typical localized regions were identified by scanning electron microscopy and their comparative elemental compositions by energy dispersion x-ray spectrometry, like "fingerprints" were determined. Paste surfaces were recognized, partly as continuous Ca-rich film, partly as compact hydrated mass on which ettringite rods, spherical aragonite grains, and other cubic and hexagonal forms are visible. The matching steel surfaces present some unaltered areas with corrosion "islands," and several products with morphologies due to different corrosion levels.