This study examines the influence of an increasing water-to-cement (w/c) ratio on the hydration mechanism of portland cement. Portland cement pastes at three w/c ratios of 0.5, 0.8 and 1.2 were prepared and cured in hermetically sealed vials at 40 °C for 14 days. Compressive strength, bulk electrical resistivity and bound water measurements were conducted. Thermogravimetric analysis was performed on hydrated pastes. Hydrated microstructures of fractured surfaces of dried pastes representing the extreme w/c ratios of 0.5 and 1.2 were investigated using scanning electron microscopy for morphology and energy dispersive X-ray spectroscopy for chemical composition and elemental mapping of hydration products. The results indicate that an increase in the w/c ratio benefits the hydration of portland cement; however, the advantageous magnitude is limited beyond a certain w/c ratio. The microstructural characteristics of pastes and the types of hydration products formed are highly governed by the w/c ratio. The effects of w/c ratio on the morphology and composition of hydration products, particularly calcium silicate hydrate and calcium hydroxide, are discussed.

中文翻译：

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高水灰比波特兰水泥浆体的微观结构和微观分析


本研究探讨了增加水灰比 (w/c) 对硅酸盐水泥水化机理的影响。制备三种水灰比为 0.5、0.8 和 1.2 的波特兰水泥浆体，并在密封小瓶中于 40°C 下固化 14 天。进行了抗压强度、体积电阻率和结合水测量。对水合糊剂进行热重分析。使用扫描电子显微镜研究了代表 0.5 和 1.2 极端水灰比的干燥浆料断裂表面的水合微观结构，以获取形态学和能量色散 X 射线光谱，以了解水化产物的化学成分和元素图谱。结果表明，水灰比的增加有利于硅酸盐水泥的水化；然而，有利的幅度被限制在超过一定的w/c比率。糊剂的微观结构特征和形成的水合产物的类型很大程度上取决于水灰比。讨论了水灰比对水化产物，特别是水合硅酸钙和氢氧化钙的形态和组成的影响。