Accelerated Reactivity Assessment of Light Burnt Magnesium Oxide

Abstract

Light Burnt magnesium oxide (MgO), also known as magnesia, has a variety of industrial applications, including as the basic ingredient of magnesium oxychloride (MOC) cement. However, it is found that the quality, reactivity in particular, of Light Burnt MgO could vary so much that the workability and performance of magnesia-based final products can be significantly affected. Consequently, how to measure the reactivity of MgO would be the key for the further development and success of industrial applications of magnesia. To solve the problem, a simple, effective and yet economical test method for evaluating the reactivity of MgO is developed in this study, which utilizes the time required for neutralization to take place between MgO particles and an acidic solution. The experimental results show that the solubility of the major salts produced during the solidsolution reactions would fundamentally alter the reaction mechanism and thus the speed of the neutralization process. Moreover, the effects of MgO reactivity on the properties of MOC cement are assessed with a series of cement pastes using different MgO batches of various qualities. Finally, a classification of Light Burnt MgO with specific reactivity ranges for different applications is recommended for end users.

Influence of magnesia-to-phosphate molar ratio on microstructures, mechanical properties and thermal conductivity of magnesium potassium phosphate cement paste with large water-to-solid ratio

“…The powder mineralogical compositions were determined by X-ray diffractometry (XRD, PANalytical X'pert) using Cu-Kα radiation (1.541874 Å, 40 mA, 40 kV) as the source, and with a scanning step of 0.05°. In addition, the reactivity of the magnesia powders was evaluated by using an accelerated reactivity method, as documented in the literature [21]. In this test, 5.0 g of the magnesia powder was mixed and stirred in 100 mL of acetic solution that had a concentration of 1.0 mol/L.…”

“…Property information of the light-burnt and dead-burnt magnesia powders: (a): XRD diffractograms; (b): magnesia reactivity tested by the acetic-acid method[21]. Temperature evolutions of the MKPC pastes during setting.…”

Characterisation of different commercial reactive magnesia

“…As peaks at smaller diffraction angles are desirable, the major characteristic peak of magnesia at 42 . 938 (2Ł) is used in the calculation (Chau and Li, 2008).…”

Setting and strength development of magnesium phosphate cement paste

“…15 It measured the time needed for neutralisation to take place between magnesia powder and acetic acid solution. After many trials, it was found that reacting 5 g magnesia powder with 100 ml of 0 .…”