Studies of historic concrete
Underground concrete repositories for nuclear waste have to maintain their integrity for hundreds of years. This study examines ancient concretes and assesses the suitability of equivalent modern materials for underground storage. The samples were examined using a variety of analytical techniques, including scanning electron microscopy, optical microscopy, chemical analysis and pH determination. The samples were also subjected to a range of physical tests. Most of the samples examined were very weak and porous. With the exception of the 19th century sample, none of the concretes had maintained pH alkaline enough to immobilise radionuclides. Hydrated calcium silicates were detected in some samples which are similar to those observed in modern Portland cement concretes. These stable cementitious species have endured for almost two thousand years. The samples studied are generally walls or floors of limited thickness. All the ancient concretes and mortars examined contain natural pozzolanic material or crushed burnt clay. This may have some effect on the reduction in alkalinity although the main reason is full carbonation of calcium hydroxide. Although the compressive strengths of the samples are generally low by modern standards (about 1-5 MPa), all the samples retain their full structural integrity.
Bibliographic Reference: EUR 12972 EN (1990) 163 pp., FS, ECU 13.75
ISBN: ISBN 92-826-1727-0
Record Number: 199011761 / Last updated on: 1994-12-02
Original language: en
Available languages: en