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Tests on Magnesium Phosphate Composite Mortar Mixtures with Different Molar Ratios of MgO-to-KH2PO4

MgO-KH2PO4 몰비 변화에 따른 마그네시아-인산염 모르타르의 배합실험

  • Yoon, Hyun-Sub (Department of Architectural Engineering, Kyonggi University Graduate School) ;
  • Lee, Kyung-Ho (Department of Architectural Engineering, Kyonggi University Graduate School) ;
  • Yang, Keun-Hyeok (Department of Plant.Architectural Engineering, Kyonggi University)
  • Received : 2016.12.12
  • Accepted : 2017.02.28
  • Published : 2017.06.20

Abstract

The objective of this study is to seek a reliable mixture proportion for magnesium potassium phosphate composite(MKPC) mortars with a near-neutral pH value (below 9.5) and a relatively good compressive strength exceeding 30MPa. The main parameter selected was the molar ratios($M_{mp}$) of $MgO-to-KH_2PO_4$ which varied from 30.4 to 3.4. The setting time of the MKPC mortars tended to shorten with a decrease in $M_{mp}$ value. With regard to the strength development ratio normalized by the 28-day strength, the ranges measured in the mortars with an $M_{mp}$ below 7.9 were 50~61% at 1 day and 60~73% at 3 days, indicating a highly rapid early-strength development. With a decrease in $M_{mp}$, the formation of struvite-K crystal identified as a primary hydration product increased, which led to the decrease of the macro-capillary pores in micro-structures. For achieving the targeted requirements for pH value and compressive strength, the $M_{mp}$ needs to be selected as below 5.1.

Acknowledgement

Supported by : Ministry of Land, Infrastructure and Transport

References

  1. Kim WJ, Yoo JH, Khil BS. Promoted high durability concrete for the construction of coastal reclaimed land. Magazine of the Korea Concrete Institute. 2012 May;24(2):37-42. https://doi.org/10.4334/JKCI.2012.24.1.037
  2. Bae SH, Park JI, Lee KM. Influence of mineral admixtures on the resistance to sulfuric acid and sulfate attack in concrete. Journal of the Korea Concrete Institute. 2010 Mar;22(2):219-28. https://doi.org/10.4334/JKCI.2010.22.2.219
  3. Hong KN, Shin JS, Han SH, Seo DW, Ahn KG. Mechanical properties of very rapid hardening polymer mortar for concrete repair. Journal of the Korean Geoenvironmental Society. 2014 Aug;15(8):31-7. https://doi.org/10.14481/JKGES.2014.15.8.31
  4. Kang IS, Ahn MY, Paik MS, Jung SJ. A study on field and hydration properties ultra rapid hardening mortar using magnesia-phosphate cement. Journal of the Architectural Institute of Korea. 2008 Jul;24(2):79-86.
  5. Kang IS, Ahn MY, Paik MS, Lim NG, Moon JS, Jung SJ. A study on the basic properties analysis of ultra rapid hardening mortar using magnesia-phosphate cement. Journal of the Architectural Institute of Korea. 2007 Aug;23(8):139-48.
  6. Yoon HS, Jung SB, Yang KH, Lee SS, Lee JY. Compressive strength and ecological characteristics of mortars using expanded vermiculite absorbing bacteria. Journal of the Korean Recycled Construction Resources Institute. 2016 Jun;4(2):165-71. https://doi.org/10.14190/JRCR.2016.4.2.165
  7. Ramachandran SK, Ramakrishnan V, Bang SS. Remediation of concrete using micro-organism. ACI Materials Journal. 2001 Jan;98(1):3-9.
  8. Zhang T, Cheesman CR, Vandeperre LJ. Development of low pH cement systems forming magnesium silicate hydrate(M-S-H). Cement and Concrete Research. 2011 Apr;41(1):439-42. https://doi.org/10.1016/j.cemconres.2011.01.016
  9. Yang Q, Wu X. Factors influencing properties of phosphate cement-based binder for rapid repair of concrete. Cement and Concrete Research. 1999 Mar;29(1):389-96. https://doi.org/10.1016/S0008-8846(98)00230-0
  10. Ding Z, Li Z. Effect of aggregates and water contents on the properties of magnesium phospho-silicate cement. Cement and Concrete Composites. 2005 Jan;27(1):11-8. https://doi.org/10.1016/j.cemconcomp.2004.03.003
  11. Sarkar AK. Hydration/dehydration characteristics of struvite and dittmarite pertaining to magnesium ammonium phosphate cement systems. Journal of Materials Science. 1991 May;26(1):2514-8. https://doi.org/10.1007/BF01130204
  12. Masuda T, Ogino I, Mukai SR. Optimizing the dimensions of magnesium ammonium phosphate to maximize its ammonia uptake ability. Advanced Powder Technology. 2013 Mar;24(1):520-4. https://doi.org/10.1016/j.apt.2012.10.001
  13. Chau CK, Qiao F, Li Z. Microstructure of magnesium potassium phosphate cement. Construction and Building Materials. 2011 Jun;25(1):2911-7. https://doi.org/10.1016/j.conbuildmat.2010.12.035
  14. Qiao F, Qiao CK, Li Z. Property evaluation of magnesium phosphate cement mortar as patch repair material. Construction and Building Materials. 2010 May;24(1):695-700. https://doi.org/10.1016/j.conbuildmat.2009.10.039
  15. Soudee E, Pera J. Influence of magnesia surface on the setting time of magnesia-phosphate cement. Cement and Concrete Research. 2002 Jan;32(1):153-7. https://doi.org/10.1016/S0008-8846(01)00647-0
  16. Korea concrete Institute, KCI Concrete Design Code, Korea concrete Institute, 2012.
  17. Vilas BS, Ravindranath TC. Synthesis and characterization of struvite-k crystals by agar gel. Journal of Crystallization Process and Technology. 2014 Oct;4(1):212-24. https://doi.org/10.4236/jcpt.2014.44026