Magnesium Oxide Board Raw Materials: Decoding the Core Secrets of New Inorganic Building Materials

Magnesium oxide board, also known as magnesia board or magnesium oxychloride board, is a popular new type of environmentally friendly inorganic building material in the construction industry. Featuring A-class fire resistance, moisture and corrosion resistance, high strength and zero formaldehyde emission, it is widely used in ceiling and partition systems, fire protection projects, industrial decoration, equipment base plates and other scenarios. Most people only understand the finished performance of magnesium oxide boards, yet they are unaware that the quality, service life and performance stability of the boards are completely determined by the proportion, purity and quality of raw materials.

Rather than a single-material panel, a magnesium oxide board is a composite panel formed by chemical curing of four major categories of raw materials: core cementitious base materials, reinforced skeleton materials, lightweight filling auxiliary materials and functional modified additives with scientific proportioning. The following is a detailed breakdown of the functions, selection criteria and core characteristics of each raw material to help you fully understand the essential material properties of magnesium oxide boards.

I. Core Cementitious Base Materials: The Fundamental Skeleton of Boards

As the core of magnesium oxide board formation, cementitious base materials determine the strength, fire resistance and stability of the boards. All auxiliary materials are formed and cured relying on the base materials. There are two mainstream core systems: magnesium oxychloride and magnesium oxysulfate.

1. Light Burned Magnesium Oxide (MgO) – Core Primary Material

Light burned magnesium oxide is the most essential base material for magnesium oxide boards. It is produced by low-temperature calcination and grinding of magnesite ore, serving as the core cementitious substance forming the cured structure of boards, and is known as the "soul material" of magnesium oxide boards.

Core Functions: It undergoes hydration reaction with magnesium salt solution to generate stable crystalline hardened bodies, endowing the boards with basic strength, rigidity, high temperature resistance and fire resistance. It directly determines the hardness, impact resistance and curing effect of finished boards.

Selection Criteria: High-quality magnesium oxide boards adopt high-activity light burned magnesium oxide with a purity of ≥80%, qualified active magnesium oxide content and uniform fineness. Low-purity and low-activity magnesium oxide will lead to incomplete curing, insufficient strength, pulverization and cracking of boards, greatly shortening their service life. At present, high-quality domestic raw materials are mainly produced in core magnesite mining areas such as Haicheng, Liaoning Province.

2. Magnesium Salt Activator – Key Curing Auxiliary Material

Divided into magnesium chloride (hexahydrate magnesium chloride flakes/powder) and magnesium sulfate, it is an essential additive to activate the hydration reaction of magnesium oxide.

Magnesium Chloride (for Magnesium Oxychloride Boards): It offers high cost performance, fast reaction speed and high curing strength, serving as the mainstream activator for traditional magnesium oxide boards. High-quality magnesium chloride features high purity and few impurities. Excessive salt content in raw materials will cause panel problems such as efflorescence, frosting, moisture absorption and deformation.

Magnesium Sulfate (for Magnesium Oxysulfate Boards): As an upgraded activator, it contains no chloride ions, completely solving the pain points of efflorescence and metal part corrosion in traditional magnesium oxychloride boards. With superior water resistance and stability, it is the preferred raw material for magnesium oxide boards used in high-end waterproof and anti-corrosion scenarios, with only a slightly higher cost.

II. Reinforced Skeleton Materials: Tensile Framework of Boards

Pure magnesium cementitious base materials are brittle and prone to fracture after curing. Therefore, reinforced materials are required to build a flexible skeleton to improve the toughness, tensile resistance and integrity of boards and avoid cracking and deformation.

1. Alkali-Resistant Glass Fiber Mesh

It is an indispensable core reinforcing material for magnesium oxide boards. Different from ordinary glass fiber cloth, special glass fiber mesh for magnesium oxide boards has excellent alkali resistance, resisting strong alkali corrosion of magnesium cement without aging or pulverization in long-term use.

Core Functions: Laid in layers inside the board and tightly combined with the cementitious base material, it forms an "inorganic composite structure", which significantly improves the tensile strength, flexural resistance and crack resistance of the board. It equips the board with both hardness and toughness, preventing breakage and warping while optimizing overall flatness. High-quality magnesium oxide boards are also called "inorganic fiberglass boards" precisely because of the composite structure of glass fiber mesh and magnesium base materials.

2. Plant Fibers (Wood Chips, Straw Powder, etc.)

As auxiliary reinforcing materials, high-quality sawdust, rice husk powder, straw fiber and other pure natural plant fibers are adopted after drying, dedusting and refining treatment.

Core Functions: They optimize the internal structure of boards, relieve the shrinkage stress of base materials during curing, and reduce the risk of dry cracking and deformation. Meanwhile, they lower the board density and self-weight for convenient transportation and installation, and slightly improve the sound insulation and heat insulation performance of boards.

III. Lightweight Filling Auxiliary Materials: Optimizing Performance and Reducing Self-Weight

Filling auxiliary materials do not participate in core chemical reactions. They are mainly used to optimize the physical properties of boards, adjust density and reduce production costs, making boards adaptable to various application scenarios.

1. Expanded Perlite

It is a lightweight porous inorganic mineral particle with light weight, non-combustibility and excellent thermal insulation, serving as the most commonly used high-quality filler for magnesium oxide boards.

Core Functions: It greatly reduces the overall weight of boards to avoid excessive building load caused by heavy panels. The porous structure significantly improves the thermal insulation and sound absorption performance while maintaining the full non-combustible feature without damaging the fire resistance of boards.

2. Functional Powder Fillers

Mainly including inert inorganic powders such as lithopone, light calcium carbonate and talc powder, which are finely ground and purified.

Core Functions: They fill tiny internal pores of boards to improve surface flatness and smoothness, reduce pore defects, enhance wear resistance and weather resistance, optimize the appearance of finished products, and adapt to secondary processing such as decorative finishing and spraying.

IV. Functional Modifiers: Quality Optimizers for Boards

Modifiers are the core difference between high-end and low-grade magnesium oxide boards. As refined chemical additives, they are added in small amounts but play a decisive role in improving the stability and service life of boards, solving the common defects of traditional magnesium oxide boards.

Common modifiers include waterproof agents, anti-efflorescence agents, retarders, toughening agents and stabilizers.

Core Functions: They target and solve board defects. Anti-efflorescence agents inhibit moisture absorption, frosting and deformation of magnesium oxychloride boards; waterproof agents improve water resistance for humid environments; toughening agents further optimize board toughness and reduce fracture risks; stabilizers enhance aging and weathering resistance to prolong the service life in outdoor and high-humidity scenarios. Magnesium oxide boards without modifiers or with inferior modifiers are prone to deformation, mildew and pulverization after 1-2 years of use.

V. Differences Between Mainstream Magnesium Oxide Board Raw Material Systems

According to different proportions of core base materials, magnesium oxide boards on the market are divided into two types. Differences in raw materials directly determine their application scenarios:

Magnesium Oxychloride Board: Composed of magnesium oxide, magnesium chloride and conventional auxiliary materials, it features high cost performance and sufficient strength. It is a universal product suitable for partition walls, ceilings and fire protection base plates in indoor dry environments.

Magnesium Oxysulfate Board: Made of magnesium oxide, magnesium sulfate and high-end modifiers, it is chloride-free, non-corrosive, superior in water and moisture resistance and more stable in performance. As a high-end upgraded version, it is applicable to high-humidity and corrosive scenarios such as bathrooms, kitchens, basements and outdoor areas.

VI. Raw Material Quality Determines Core Board Performance

The huge price gap of identical-looking magnesium oxide boards essentially stems from differences in raw material grades and proportioning processes. Low-grade boards adopt low-purity magnesium oxide, inferior industrial magnesium chloride powder, non-alkali-resistant glass fiber cloth and no modifiers. They look qualified in the short term but tend to have problems such as efflorescence, cracking and deformation, pulverization and falling off, and moisture-induced mildew in long-term use.

High-quality national standard magnesium oxide boards strictly comply with GB/T 33544-2017 standards. Adopting high-purity and high-activity magnesium oxide, premium magnesium salt, high-density alkali-resistant glass fiber mesh and compliant modifiers with scientific proportioning and sufficient chemical reaction, the finished boards integrate fire resistance, waterproof performance, stability, durability and environmental protection, suitable for various industrial, residential and special engineering scenarios.

Conclusion

A magnesium oxide board is a composite raw material system of "cementitious base curing + skeleton reinforcement + auxiliary optimization + additive modification", with no single core material. Each raw material performs its own functions and cooperates with others. Understanding the raw material composition of magnesium oxide boards helps accurately distinguish board quality, avoid inferior low-cost products and select suitable boards according to actual application scenarios.