Ceramics-Silikáty |
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HARDENING PROPERTIES AND HYDRATION MECHANISMS OF BMSC AND BMS-IS CEMENTITIOUS MATERIALS PREPARED USING MGO WITH VARYING ACTIVITIES
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Jin Luyao 1,2, Huang Lei 1,2, Zhang Xuewei 3
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1 School of civil engineering and water resources, Qinghai University, Xining 810016, China.
2 Qinghai Provincial Key Laboratory of Energy-saving Building Materials and Engineering Safety, Xining 810016, China.
3 The First Construction Engineering Company Ltd. of China Construction Second Engineering Bureau, Beijing 100176, China.
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Keywords: Basic magnesium sulfate cement, Iron slag, Magnesium oxide, Compressive strength, Water resistance
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The study investigates the influence of the MgO activity on the hydration and hardening performance of basic magnesium sulfate cement (BMSC) and BMSC with iron slag (BMSC-IS). The compressive strength and water resistance of both BMSC and BMSC-IS were evaluated, while their microstructure, hydration products, and hydration kinetics were analysed in detail. The results indicate that the MgO activity significantly affects the strength development of BMSC and BMSC-IS. Specifically, BMSC prepared with low-activity MgO (LA-BMSC) exhibits a slower initial hardening process, but demonstrates sustained and substantial strength gain over time. In contrast, BMSC prepared with high-activity MgO (HA-BMSC) experiences a phenomenon of strength retrogression. Within the HA-BMSC system, the formation of fine-grained 5Mg(OH)₂-MgSO₄-7H₂O (5-1-7 phases) and abundant Mg(OH)₂ occurs simultaneously; the continuous growth of Mg(OH)₂ can lead to matrix cracking. Conversely, the LA-BMSC system primarily produces coarse-grained 5-1-7 phases, resulting in superior water resistance compared to HA-BMSC. The addition of IS generally reduces the compressive strength of BMSC and delays its hydration and hardening processes, yet it enhances the long-term water resistance of HA-BMSC. |
doi: 10.13168/cs.2025.0019
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