Potential use of borosilicate glass to make neutron shielding mortar: Enhancement of thermal neutron shielding and strength development and mitigation of alkali-silica reaction

Abstract

From a sustainability point of view, the disposal of non-recyclable glasses like Pyrex, tempered glass, and borosilicate glass gradually become an environmental issue because non-recyclable glass is a non-biodegradable material. To obtain high glass recycling ratios without remelting, many researchers have used not only crushed glass as an alternative to both fine and coarse aggregate in concrete, but also used ground glass powder as a pozzolanic material to enhance the formation of calcium silicate hydroxide (CSH). In general, concrete is known as a good fast neutron moderator due to its high hydrogen content but does not contain boron compound used for absorption of a thermal neutron. In this work, borosilicate glass was, therefore, used as a form of mineral additive and fine aggregate to produce neutron shielding mortar in this work. Furthermore, it was investigated whether the use of borosilicate glass powder can mitigate the expansion caused by alkali-silica reaction (ASR) between alkali in cement and the reactive silica in borosilicate glass aggregate or not. Test results indicate that 20% borosilicate glass powder replacing cement was able to control the ASR expansion. When borosilicate glass powder and aggregates were used simultaneously, the compressive strength of the mortar mixture increased. Moreover, the combined use of borosilicate glass powder and aggregates could shield 86% additional thermal neutron, leading to the possibility of using borosilicate glass for neutron shielding purposes.