Journal of Central South University

, Volume 20, Issue 12, pp 3729–3735 | Cite as

Effects of H3PO4 and Ca(H2PO4)2 on mechanical properties and water resistance of thermally decomposed magnesium oxychloride cement

  • Jing Wen (文静)
  • Hong-fa Yu (余红发)
  • Ying Li (李颖)
  • Cheng-you Wu (吴成友)
  • Jin-mei Dong (董金美)
  • Li-na Zheng (郑利娜)
Article
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Abstract

The effects of H3PO4 and Ca(H2PO4)2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement (TDMOC) pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca(H2PO4)2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient (K n ) increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg(OH)2·MgCl2·8H2O in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.

Key words

thermally decomposed magnesium oxychloride cement (TDMOC) H3PO4 Ca(H2PO4)2 strength water resistance hydration heat 
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Copyright information

© Central South University Press and Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Jing Wen (文静)
    • 1
    • 2
  • Hong-fa Yu (余红发)
    • 1
    • 3
    • 4
  • Ying Li (李颖)
    • 1
    • 2
  • Cheng-you Wu (吴成友)
    • 1
    • 2
  • Jin-mei Dong (董金美)
    • 1
    • 2
  • Li-na Zheng (郑利娜)
    • 1
    • 2
  1. 1.Qinghai Institute of Salt LakesChinese Academy of SciencesXiningChina
  2. 2.Graduate School of Chinese Academy of SciencesBeijingChina
  3. 3.Department of Civil EngineeringQinghai UniversityXiningChina
  4. 4.Department of Civil EngineeringNanjing University of Aeronautics and AstronauticsNanjingChina

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