Novel magnesium oxychloride cement mixed by water

Abstract

The invention relates to novel magnesium oxychloride cement mixed by water, which is obtained by mixing and grinding 50-100 parts of a part of pyrolysis product of bischofite, 0.5-5 parts of organic acid, 0-50 parts of active mixed materials and 0-5 parts of monocalcium phosphate into 180 meshes. The novel magnesium oxychloride cement has the characteristics of low solution heat, low hydration heat and high strength.

Description

technical field [0001] The invention relates to a magnesium oxychloride cement, in particular to a novel magnesium oxychloride cement mixed with water. Background technique [0002] Magnesium oxychloride cement is a kind of magnesium chloride (MgCl) with a certain concentration 2 ) solution mixed with light-burned magnesium oxide (MgO) powder, which was invented by the Frenchman Sorel in 1867. It has early strength, high strength, fire prevention, sound insulation, heat insulation, and good decorative effect. It is light in weight, easy to process and shape, and has strong bonding ability with organic-inorganic materials. Since its invention, it has been widely used in construction, transportation, water conservancy, salt lake chemical industry and other industries. The two main raw materials of magnesium oxychloride cement are mainly light-burned magnesia and magnesium chloride. my country has abundant raw materials for magnesium oxychloride cement, among which light-burne...

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Problems solved by technology

Chinese invention patent 200810150359.1 discloses a method for preparing magnesium cement by partial pyrolysis of magnesium chloride. The method is to put salt lake bischofite or salt lake brine into the pyrolysis equipment, and the decomposition temperature is 450~750°C, and the decomposition time is Under 5~90min, thermally decompose bischofite to obtain a solid product containing magnesium oxide and magnesium chloride, in which the molar ratio of MgO:MgCl2 is 4:1~6:1. Magnesium cement can be mixed directly with water, the process is simple, and the operation is convenient, but this magnesium oxychloride cement has two fatal shortcomings in the process of mixing with water: (1) After the cement is mixed with water, the anhydrous magnesium chloride therein dissolves immediately, resulting in Very high heat of dissolution and heat of hydration, and a large amount of heat of dissolution and heat of hydration are released violently in the early stage, while maintaining MgO:MgCl2:H2O mole Under the condition of 6.83:1:27, the total heat release of hydration for 24 hours is 786.07 J / g, which is 52.4% higher than that of traditional magnesium oxychloride cement (515.66 J / g). , within 26 minutes of hydration, 40% of the total heat released in 24 hours of hydration was concentrated for the first time, and 55% of the total heat released in 24 hours of hydration was concentrated in the second release within 2 hours of hydration, while traditional magnesium oxychloride cement not only The heat release is relatively low, and only 10% of the total heat release in 24 hours of hydration is concentrated and released for the first time within 26 minutes of hydration, and the time of the second intense heat release is delayed until after 7 hours of hydration, that is, after 7 hours of hydration. The heat only accounts for 39% of the total heat released in 24 hours of hydration (see Figure 1 and Figure 2), which leads to The temperature of the slurry of magnesium oxychloride cement prepared according to this method rises sharply, exceeding 120-150°C, and even boiling occurs, which brings dangers such as burns to the operator; The heat of hydration makes it difficult to form a stable coagulated and hardened slurry structure during the hardening process of cement, resulting in severe cracking and deformation of the product, low strength, or even complete loss of strength. In fact, it is difficult to popularize and use

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