Basic magnesium sulfate cement and preparation method thereof

Abstract

The invention discloses basic magnesium sulfate cement which comprises the following components in parts by mass: 100 parts of active magnesium oxide powder, 30-100 parts of a magnesium sulfate solution, 0.01-0.05 part of an additive and 0.1-5 parts of a magnesium oxysulfate crystal nucleating agent, the magnesium sulfate solution is an aqueous solution of crystallized magnesium sulfate, and the mass fraction of the magnesium sulfate solution is 15-20%; the magnesium oxysulfate crystal nucleating agent is prepared by the following method: step 1, mixing 50-100 parts by mass of light calcined magnesite powder with the active MgO mass fraction of 55%-85%, 70-300 parts by mass of a magnesium sulfate solution with the active MgO mass fraction of 10%-25% and 0.01-0.05 part by mass of phosphoricacid; and 2, putting the paste obtained in the step 1 into a sealed bag, curing at 20+ / -3 DEG C for 28 days to promote hardening, and finally grinding the hardened sample into powder through ball milling to obtain the actual magnesium oxysulfide crystal nucleating agent. The basic magnesium sulfate cement has the advantages of short setting time, early strength, high strength and the like.

Description

technical field [0001] The invention belongs to the field of building materials, and relates to cement, in particular to basic magnesium sulfate cement and a preparation method thereof. Background technique [0002] MgO-MgSO 4 -H 2 O cement is an inorganic gelling material formed by mixing magnesium oxide and magnesium sulfate solution and adding certain admixtures. It belongs to an air-hardening magnesium material, and its main hydration product is 3Mg(OH) 2 · MgSO 4 ·8H 2 O (referred to as 3.1.8). Currently for MgO-MgSO 4 -H 2 O The modification technology of the ternary gelling system mostly uses organic carboxylic acid and other retarders to obtain a basic magnesium sulfate cement with excellent performance, and its main hydration product is 5Mg(OH) 2 · MgSO 4 ·7H 2 O (referred to as 5.1.7). The addition of these admixtures improves the strength and volume stability of basic magnesium sulfate cement by changing the composition of its hydration phase. Although ...

AI Technical Summary

Problems solved by technology

Although the late strength of basic magnesium sulfate cement is higher, based on the retarding effect of the admixture, the product hardens slowly. The final setting time at room temperature generally exceeds 6 hours, and its 1-day strength is also much lower than that of magnesium oxychloride cement. Many, which pose very difficult problems for the production efficiency and scale production of basic magnesium sulfate cement products

[0003] The traditional inorganic electrolytes (such as sodium chloride, sodium sulfate, aluminum sulfate, etc.), triethanolamine, formate and other early strength agents used in Portland cement-based materials not only cannot accelerate the setting of the basic magnesium sulfate cement system rate, and will continue to prolong its coagulation time

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