Journal of the Korea Institute of Building Construction (한국건축시공학회지)

The Korean Institute of Building Construction (한국건축시공학회)
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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
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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.

본 연구에서는 중성급 pH와 30 MPa 이상의 압축강도를 갖는 마그네시아-인산칼륨 복합체(Magnesia-potassium phosphate composites, MKPC) 모르타르의 배합설계를 위하여 마그네시아(MgO)와 인산칼륨($KH_2PO_4$)의 혼합 몰비($M_{mp}$)를 30.4에서 3.4로 변화하였다. MKPC 모르타르의 응결시간은 $M_{mp}$가 감소함에 따라 짧아졌다. 재령 28일 강도로 일반화된 강도 발현율은 $M_{mp}$가 7.9이하인 배합의 경우 재령 1일에서 50~61% 수준이었으며, 재령 3일에서는 60~73% 수준으로서 초기재령에서 빠른 강도발현성능을 나타냈다. MKPC의 수화생성물인 스트루바이트-K의 양은 $M_{mp}$가 감소할수록 증가하였는데, 이로 인해 거대공극 분포도 감소하였다. MKPC 모르타르의 목표로 했던 성능을 고려하면, $M_{mp}$의 값은 5.1 이하가 요구되었다.

Keywords

References

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