Title:
Concrete After 30 Years of Exposure - Part 1: Minearlogy, Microstructure, and Interfaces
Author(s):
Tarek Uddin Mohammed, Hidenori Hamada, and Toru Yamaji
Publication:
Materials Journal
Volume:
101
Issue:
1
Appears on pages(s):
3-12
Keywords:
aggregate; cement; porosity
DOI:
10.14359/12982
Date:
1/1/2004
Abstract:
A detailed investigation was carried out on 30-year-old concrete specimens made with ordinary portland cement (OPC), high early- strength portland cement (HES), Type B slag cement (SCB), and alumina cement (AL). In each specimen, steel bars were embedded at cover depths of 20, 40, and 70 mm. Mineralogy and microstructure of mortar portions at the inner and outer regions, aggregate-matrix and steel-matrix interfaces, and deposits in the voids of the mortar portions were investigated. It is concluded from the results that the microstructure of concrete at the outer region for AL and SCB becomes denser compared with the inner region. For AL, the inner region is relatively more porous, and a porous steel-concrete interface is also found. Other conclusions on the ingress of SO3 and Cl, leaching of Ca, and healing of voids in concrete are also summarized herein.