ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 64, (1) 7 - 17 (2020)


THE EFFECTS OF CALCIUM AND POTASSIUM DIHYDROGEN PHOSPHATE ON THE PROPERTIES OF MAGNESIUM OXYSULFATE CEMENTS
 
Luo Kejia 1, Wu Chengyou 1,2, Li Zhen 1,Liu Panpan 1, Pang Ruiyang 1, Chen Cong 1, Chen Yuanji 1, Zhang Huifang 3 , 4
 
1 School of Civil Engineering, Qinghai University, Xining 810016, PR China
2 Key Laboratory of Building Energy-saving Materials and Engineering Safety of Qinghai Province, Xining 810016, PR China
3 Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, PR China
4 Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Xining 810008, PR China

Keywords: Magnesium oxysulfate cement, Setting time, Compressive strength, Hydration heat release, Porosity
 

Magnesium oxysulfate (MOS) cement is a newly-developed material,which shows the advantages of being protected from steel, being light weight, having low alkalinity, being fire-proof, and having a decorative value. Large-scale applications of MOS cement in civil engineering have been restricted by its low strength, which can be improved by adding the proper additives. Here, the effects of dihydrogen phosphate on the setting time, compressive strength, and water resistance of the MOS cement have been studied. The studies on the effects of dihydrogen phosphate on the hydration process of the MOS cement have been studied relative to the hydration-heat release rate. X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry were used to examine the hydration products and the pore-size distribution of the MOS cement. The analytical results show that dihydrogen phosphate as an admixture can reduce the direct hydration of MgO into Mg(OH)₂, promote the formation of the 5·1·7 strength phase, and improve the strength and water resistance of the cement to some extent. However, dihydrogen phosphate will prolong the setting time of the cement to some extent.


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doi: 10.13168/cs.2019.0043
 
 
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