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Title |
Effect of Phosphate-to-binder and Water-to-binder Ratio on Magnesia-potassium Phosphate Cement
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Authors |
이경호(Kyung-Ho Lee) ; 윤현섭(Hyun-Sub Yoon) ; 양근혁(Keun-Hyeok Yang) |
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DOI |
https://doi.org/10.4334/JKCI.2017.29.3.275 |
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Keywords |
마그네시아-인산염 시멘트 ; 물-결합재 비 ; 인산염-결합재 비 ; 응결시간 ; 압축강도 magnesia-phosphate cement ; water-to-binder ratio ; phosphate-to-binder ratio ; setting time ; compressive strength |
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Abstract |
This study examined the effect of water-to-binder ratio (W/B) and phosphate-to-binder ratio (P/B) on the flow, setting time, compressive strength development, and pH variation of magnesium-potassium phosphate composites, MKPC mortars. Ten mortars mixtures were prepared with the W/B varying from 20% to 40% at each P/B of 0.3 or 0.5. The hydration products and microstructural pore distribution of the MKPC pastes were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP). The initial flow and setting time of MKPC mortars tended to decrease with an increase of P/B, indicating that the final setting time was shortened by approximately 24% when P/B increased from 0.3 to 0.5. The slope of the early-strength development measured in the MKPC mortars was considerably higher than that of cement concrete specified in code provisions. For obtaining a relatively good 28-day strength (above 30 MPa) and a near neutral pH (below 9.0) in MKPC mortars, the P/B and W/B need to be selected as 0.5 and 30%, respectively. The strubite-K crystal increased with the increases of P/B and W/B, which leads to the decrease of the macro-capillary pores.
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