Abstract
Magnesium oxychloride cement (abbreviated as MOC) was prepared using magnesium residue obtained from Li2CO3 extraction from salt lakes as raw material instead of light magnesium oxide. The properties of magnesium residue calcined at different temperatures were researched by XRD, SEM, LSPA, and SNAA. The preparation of MOC specimens with magnesium residue at different calcination temperatures (from 500 °C to 800 °C) and magnesium chloride solutions with different Baume degrees (24 Baume and 28 Baume) were studied. Compression strength tests were conducted at different curing ages from 3 d to 28 d. The hydration products, microstructure, and porosity of the specimens were analyzed by XRD, SEM, and MIP, respectively. The experimental results showed that magnesium residue’s properties, the BET surface gradually decreased and the crystal size increased with increasing calcination temperature, resulting in a longer setting time of MOC cement. Additionally, the experiment also indicated that magnesium chloride solution with a high Baume makes the MOC cement have higher strength. The MOC specimens prepared by magnesium residue at 800 °C and magnesium chloride solution Baume 28 exhibited a compressive of 123.3 MPa at 28 d, which met the mechanical property requirement of MOC materials. At the same time, magnesium oxychloride cement can be an effective alternative to Portland cement-based materials. In addition, it can reduce environmental pollution and improve the environmental impact of the construction industry, which is of great significance for sustainable development.
Highlights
Known as magnesium oxychloride cementitious material, refers to a gas-hardening cementitious material formed by mixing a certain concentration of magnesium chloride solution with lightly burned oxide powder, which was first discovered by Sorel in 1867 [1,2,3]
The results showed that it is feasible to use the calcination method to extract lithium byproducts instead of light-burned powder to prepare magnesium oxysulfide cement
The raw material of magnesium residue used in this experiment originated from the byproduct of Li2CO3 extracted by Qinghai Citic Guoan Technology Development Company
Summary
Known as magnesium oxychloride cementitious material, refers to a gas-hardening cementitious material formed by mixing a certain concentration of magnesium chloride solution with lightly burned oxide powder, which was first discovered by Sorel in 1867 [1,2,3]. The extraction of lithium carbonate products from the salt lake brine will have many magnesium residues byproducts [16]. Tan et al [38] used the calcination method to extract the lithium byproduct and prepared magnesium phosphate cement with conforming setting time and mechanical properties without adding any retarder. Wu et al [40] used the calcination method to extract lithium byproducts to prepare magnesium oxysulfide cement and measured the setting time, mechanical properties, hydration products, and microstructure. The results showed that it is feasible to use the calcination method to extract lithium byproducts instead of light-burned powder to prepare magnesium oxysulfide cement. The influence of calcination temperature on active magnesia properties and its setting time, hydration heat, compressive strength, and hydration of obtained MOC cement was thoroughly researched
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