Multi-scale characteristics of magnesium potassium phosphate cement modified by metakaolin |
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| Affiliation: | 1. College of Civil Engineering, Shaoxing University, Shaoxing, 312000, China;2. Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province, Shaoxing, 312000, China;3. School of Materials Science and Engineering, Southeast University, Nanjing, 211189, China;4. School of Civil Engineering, Central South University, Changsha, 410075, China;5. Zhejiang Yongjian New Material Technology Co., Ltd, Shaoxing, 312000, China;6. Institute of Urban Smart Transportation & Safety Maintenance, Shenzhen University, Shenzhen, Guangdong, 518061, China |
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| Abstract: | Workability and early-ages mechanical properties are important indicators of magnesium potassium phosphate cement (MKPC) as a repair material. The effect of metakaolin (MK) on the setting time, fluidity and early-ages strength of MKPC paste was studied, and its influence mechanism was analyzed through pore structure, microstructure and nanomechanical properties. The results show that 10% and 20% of MK prolong the setting time of MKPC paste, but excessive MK shortens the setting time of MKPC paste. Meanwhile, incorporating MK reduces the fluidity of MKPC paste, and the early-ages strength of MKPC specimens increases when the substitution ratio of MK is 10%. When 10% of MK is incorporated to the MKPC paste, the 30-d shrinkage of the sample is only 69% of the control group. Meanwhile, a proper amount of MK can improve the pore structure of the MKPC specimen and make its microstructure denser by generating amorphous aluminosilicate phosphate gel. It is observed from the nano-scale characteristics that incorporating 10% MK can reduce the content of pore phase and unreacted MgO phase, and increase the volume fraction of hydration products. |
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| Keywords: | Metakaolin Magnesium potassium phosphate cement Workability Early-ages strength Nano-scale characteristics Volume stability |
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