Magnesia (MgO) Production and Characterization, and Its Influence on the Performance of Cementitious Materials: A Review

Abstract

This paper presents a literature review concerning the characteristics of MgO (magnesium oxide or magnesia) and its application in cementitious materials. It starts with the characterization of MgO in terms of production processes, calcination temperatures, reactivity, and physical properties. Relationships between different MgO characteristics are established. Then, the influence of MgO incorporation on the properties of cementitious materials is investigated. The mechanical strength and durability behaviour of cement pastes, mortars and concrete mixes made with MgO are discussed. The studied properties of MgO-cement mixes include compressive strength, flexural strength, tensile strength, modulus of elasticity, water absorption, porosity, carbonation, chloride ion penetration, shrinkage, expansion, and hydration degree. In addition, microscopic analyses of MgO-cement mixes are also assessed. Summarizing the results of different studies, it is concluded that MgO incorporation in cementitious materials generally decreases the mechanical strength and shrinkage, and increases the porosity, expansion, carbonation and chloride ion migration. However, it should be emphasized that the properties of the specific MgO used (mainly the calcination temperature, the reactivity and the surface area) have a significant influence on the characteristics of the cementitious materials produced.

Keywords: cementitious materials; chemical properties; durability; literature review; magnesium oxide; mechanical properties; microscopic analysis; physical properties; reactivity.

Figure 1

(a) Effect of calcination temperature and residence time on the surface area and neutralization time of MgO. (b) Relationship between the surface area and the neutralization time of MgO (adapted from Mo et al. [37]).

Figure 2

Isothermal calorimetry of MgO-cement pastes showing (a) heat flow and (b) cumulative heat. (c) Thermogravimetric analysis (hydration degree) of MgO-cement pastes (adopted from [51]).