INFLUENCE OF SEVERE CONDITIONS ON THE CONCRETE EMPLOYED IN NUCLEAR TECHNOLOGY

Abstract

This thesis is mainly concentrating on honing the efficiency of Heavy-weight High­ performance (HWHP) concrete, developed from local aggregates together with additives that are waste products of other manufacturing processes, for the purpose of producing radiation shields, to attenuate gamma-rays in peaceful active-service facilitations. In other words, the thesis is an attempt to develop a special type of heavy concrete of various advantages that would enhance its performance in severe environment. Such advantages may embrace concurrent improvements; such as high specific gravity, workability, high compressive strength, efficient attenuator for gamma radiation, and resistant to elevated heat temperature along with chemical attack.

The named HWHP concrete was mainly prepared using two types of heavy aggregates, ilmenite (iron ore) and barite. In addition usual concrete (dolomite/sand) was also employed in this thesis to compare the obtained HWHP concrete. The practical facet of this thesis accounts for evaluating the influence of severe conditions, concomitm{tly and consecutively, on mechanical, morphological and attenuation characteristics for the three tyres of concrete.

Thanks to the state of the art analytical techniques, it was possible to employ XRD, DTA, TGA, IR, and Electron micro-scanning through out this research. Such types of analyses were deployed in such a way to converge at the end to construct an integrated rational, at micro-structure level, that accounts for the results obtained from tests of compressive strength; carried out for the three types of concrete.

Not only were the concrete samples, of 15 em cubes, prepared at the same conditions, but also they were e posed to a deployed.s.ystem of severe environment Thus, the three types of concrete samples were divided into four groups; the first group, of different concrete cubes, was exposed to elevated heat temperature that reached up to ten cycles at 400 °C at 60-minute cycles. In addition, another set of concrete cubes was exposed to chemical attack, which reached up to nine cycles of intervals of ten minutes.