Experimental research of magnesite cementitious materials modifier
1. Overview
Magnesite cementing materials are mixed by active MgO style and reconcile agent solution (MgCl2), and get a base type magnesium chloride (2 mg (OH) Cl) curing body, appearance and strength are like Portland cement, called magnesium oxychloride cement, also called magnesite cement. Its advantage: products don't need moisture curing; Strength increasing is fast, high flexural, compressive strength; weakly basic, low corrosion resistance; it has good cementing properties to organic and inorganic materials.

But some performance shortcomings hinder the wide range application of magnesite cementitious material, such as, weak water resistance, easy absorption of moisture condensation return halide, fast summer time affecting the operation, and poor compaction.

2. Experimental research of magnesite cementitious materials modifier

The hydration hardening characteristics of magnesite cementitious materials

In production process, due to the need of operation process, in general, the amount of the brine is more, means MgO /MgCl2 is low, the excess of MgCl2 is inevitable, and MgCl2 is strong moisture absorption agent, solubility in water is big. After the products internal moisture migration to the surface, evaporation into the air, the MgCl2 dissolved by water in products will be crystallized on the wool stoma and crack of the surface. When the air medium humidity becomes larger (rainy days) or put the products in high humidity places (such as the basement), the crystallization of Mg (OH) 2 absorbs moisture condensation of air to the product surface, damp, in turn, sweat, seriously water flows, this is known as the moisture absorption of bittern. If artificially improving Mg0 / MgCl2 ratio, the reaction of active MgO is incomplete, making the Mg (OH) 2 incompletely into crystal, when maintenance, white precipitate will be left on the products surface. In addition, the brine contains many soluble alkali metal salts (KC1, NaCI, etc.), in the process of hydration, soluble alkali metal salt along the micro hole products extends to the surface, evaporation and then leaves a white precipitate, forms "cream", and causes products fade, efflorescence, uneven color, etc.