Evaluation of Durability of Mortars and Concretes Used in Ancient Structures
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Evaluation of Durability of Mortars and Concretes Used in Ancient Structures A. S. Aloy1 (Khlopin Radium Institute, St. Petersburg, Russia, 28, 2-nd Murinsky pr.) J.R.Harbour2, E.W.Holtzscheiter2, C.A.Langton2 (Savannah River National Laboratory, Aiken, 29808, USA)
ABSTRACT The data on historic mortars and concretes provide qualitative and quantitative information to evaluate long-term behavior of cement materials in repositories and to understand processes that may occur in repositories (e.g., interaction with other materials and radionuclide transfer). Beyond that, such information is important to demonstrate safety aspects of the repositories to the public and stakeholders. A number of reports have been devoted to study of historical mortars and concretes used in the Western countries. The purpose of this paper is to review studies on compositions and structures of analogs, located mainly over the former Soviet Union’s territory. INTRODUCTION The current safest and technically feasible method for long-term containment of radioactive waste is considered to be its disposal in geological repositories, i.e., subsurface repositories for low-activity and intermediate-activity waste, and deep geological repositories for high-activity and some types of intermediate-activity waste. The durability of waste containment in repositories depends on the conditions of the entire containment system. This system includes engineering barriers (a matrix that reliably retains radionuclides, a container for packaging waste, and a buffer material), as well as natural barriers (rock materials of the repository). This system should be selected (or designed) to assure the required containment of hazardous radionuclides for the required period of time stipulated in the major radiation safety requirements. In their laboratory and full-scale studies, scientists evaluate natural analogs to assess stability and durability of cement materials intended for use in the waste repositories. Studies of natural analogs allow evaluation of available natural conditions and materials, thereby providing information applicable for the waste repositories. Another aspect of natural analog studies is related to studies of man-made materials existing under natural conditions during the time comparable with the time planned for the period of waste disposal in repositories. Such analogs are defined as archeological or industrial analogs [1]. Regarding cements and concretes, historic mortars and concretes can be considered to be archeological analogs. The data on historic mortars and concretes which can provide qualitative and quantitative information to evaluate long-term behavior of cement materials in repositories and to understand processes that may occur in repositories (e.g., interaction with other materials and radionuclide transfer). Beyond that, such information is important to demonstrate safety aspects of the repositories to the public and stakeholders. Historic mortars and concretes include ancient (dating back to antique times) and medieval mortars
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