期刊
CONSTRUCTION AND BUILDING MATERIALS
卷 269, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2020.121811
关键词
Alkali activated binder; Low curing temperature; Hydration process; Electrical resistivity; Microstructure; Pore characteristics
资金
- National Natural Science Foundation of China [41701060]
- State Key Laboratory of Frozen Soil Engineering [SKLFSEZT17]
- Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences
This study investigated the effects of low-temperature curing on the mechanical properties, hydration process, hydration products, pore characteristics, and microstructure of alkali activated FA and GGBFS mortar. The results showed that low-temperature curing decreased the compressive strength, delayed the hydration process, and resulted in the formation of harmful pores in the alkali activated mortar.
Alkali activated concrete, a green building material with excellent mechanical properties and durability, is the most promising building material for use in the continuously increasing number of infrastructure construction projects in cold regions. However, at present, there are few studies evaluating the performance of alkali activated concrete cured in a low-temperature environment. In the present work, 50% fly ash (FA) and 50% ground granulated blast furnace slag (GGBFS) were used as composite cementitious materials to prepare four groups of alkali activated mortar samples, which were cured at -5 degrees C, 0 degrees C, 5 degrees C and 20 degrees C. The effects of low curing temperature (-5 degrees C, 0 degrees C, and 5 degrees C) on the mechanical properties, hydration process, hydration products, pore characteristics and microstructure of alkali activated FA and GGBFS (AAFG) mortar were investigated with uniaxial compressive strength tests, resistivity measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). The results indicated that low-temperature curing reduced the compressive strength of the alkali activated mortar. The resistivity curves of the four groups of samples well reflected the influence of different curing temperatures on the early hydration process of the alkali activated binder. A low curing temperature delayed the hydration process and showed an obvious hysteresis effect. The lower the curing temperature was, the more significant the effect. The hydration reaction was not stopped when the sample was cured at -5 degrees C. Low curing temperatures did not change the type of hydration products but changed their amount. Low-temperature curing resulted in the formation of harmful pores. (C) 2020 Elsevier Ltd. All rights reserved.
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