Title: Mechanism of Seawater Attack on Concrete

Author(s): G. L. Kalousekand E. K. Benton

Publication: Journal Proceedings

Volume: 67

Issue: 2

Appears on pages(s): 187-192

Keywords: binders (materials) ; brucite; C3AH6;cement pastes; chlorides; chloroaluminate; crystallization;differential thermal analysis; ettringite;expansion; gysum; magnesium sulfates; nucleation.

DOI: 10.14359/7261

Date: 2/1/1970

Abstract:
Type I (white), II, and V (zero c3A) cement pastes of water-cement ratios of 0.3 and 0.5 were immersed in seawater and solutions of sodium and magnesium sulfates. The attack on the cement pastes was interpreted in terms of kinds, amounts, and location of the reaction products in the pastes. X-ray diffraction and differential thermal analysis were used in studying the specimens. Ettringite in Type I cement pastes precipitated as crystals. Growth of these in confined sites caused expansion. The ettringite in Type V cement pastes precipitated and persisted as a gel. Since there was no crystal growth, expansion did not occur. The role of chloroaluminate, btucite, and gypsum is discussed.