Alkali-Silica Reactivity of High Density Aggregates for Radiation Shielding Concrete

Abstract

Long-term exposure of concrete to nuclear reactor environments may enhance the ageing phenomena. An investigation concerning a possible deleterious alkali-silica reaction (ASR) in concrete containing high-density aggregates is presented in this paper. The scope of this investigation was limited to heavy aggregates that could be used for the construction of the first Polish nuclear power plant (NPP). Five different high-density aggregates were selected and tested: three barites, magnetite, and hematite. Mineralogical analysis was conducted using thin section microscopic observation in transmitted light. The accelerated mortar beam test and the long-time concrete prism test were applied to estimate the susceptibility of heavy aggregates to ASR. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were conducted on aggregates and mortars. The quartz size in aggregate grains was evaluated using image analysis. Application of the accelerated mortar beam method confirmed the observations of thin sections and XRD analysis of high-density aggregates. The microcrystalline quartz in hematite aggregate and cristobalite in one of barite aggregate triggered an ASR. The composition of ASR gel was confirmed by microscopic analysis. The long-term concrete test permitted the selection of innocuous high-density aggregates from among the other aggregates available, which showed practically no reactivity.

Development of Heavyweight Self-Compacting Concrete and Ambient-Cured Heavyweight Geopolymer Concrete Using Magnetite Aggregates

“…Heavyweight concrete is broadly utilized material for reactor protecting because of its less expensive and attractive mechanical properties [1,2]. The heavyweight aggregates in concrete plays an imperative role in enhancing solid protecting properties and has been demonstrated to have great shielding properties for lessening photons and neutrons [3,4].…”

Alkali-silica reaction and microstructure of concrete subjected to combined chemical and physical exposure conditions

“…Six different coarse aggregates were used: amphibolite (A), basalt (B), granite (G), dolomite (D), limestone (L), and crushed from glacial deposit (Gr). The petrographic analysis of the above aggregates is presented in [13,14]. Concrete mixes were designed with constant cement content (360 kg/m 3 ), constant water to cement ratio of 0.45, a constant slump of 100÷180 mm and the air content from 5.5% to 7.5% in the fresh mix.…”

Evaluation of the effects of bismuth oxide (Bi2O3) micro and nanoparticles on the mechanical, microstructural and γ-ray/neutron shielding properties of Portland cement pastes

“…Concrete is one of the most common materials used for radiation protection in radiation therapy facilities and nuclear reactors, as well as for preventing radiation leakage from radioactive sources. Since one of the main concrete components is aggregate, radiation shielding properties of concrete can be controlled by choice of proper normal-or heavy-weight [8][9][10] aggregate type. It is an inexpensive material with a high potential for incorporating a great variety of wastes and secondary raw materials [11][12][13].…”