Alanazi Hani
Department of Civil and Environmental Engineering, College of Engineering, Majmaah University, AL-Majmaah 11952, Saudi Arabia.
Gels. 2022 Feb 9;8(2):105. doi: 10.3390/gels8020105.
The properties and performance of geopolymer at different length scales have been intensively studied, but only limited studies on geopolymer have investigated the zone located between paste and aggregates, which is called the interfacial transition zone (ITZ). The microstructure of ITZ and its nanomechanical properties in geopolymer concrete are examined in this study. Fly ash-based geopolymer has great potential to be an alternative to traditional concrete. To this end, scanning electron microscopy (SEM) and nanoindentation tests were performed to investigate the microstructural characteristics and nanomechanical properties of the ITZ, and the results were compared with the ITZ of traditional concrete. Results show that traditional concrete demonstrated a weak ITZ with pores and microcracks, while the geopolymer concrete microstructure did not present weak ITZs in the vicinity of aggregates. More pores and crack were observed in the ITZ in traditional concrete. Further, a considerable amount of fly ash particles, that appear to be unreacted or partially reacted in the matrix phase, was observed. Based on the nanoindentation results, 58% of the microstructure is composed of unreacted or partially reacted fly ash particles. The results of nano- and microscale tests will enhance the understanding of how concrete behaves and performs at large scales.
地聚合物在不同长度尺度下的性能已经得到了深入研究，但关于地聚合物的研究中，仅有有限的研究涉及到浆体与骨料之间的区域，即界面过渡区（ITZ）。本研究考察了地聚合物混凝土中ITZ的微观结构及其纳米力学性能。基于粉煤灰的地聚合物具有很大的潜力成为传统混凝土的替代品。为此，进行了扫描电子显微镜（SEM）和纳米压痕试验，以研究ITZ的微观结构特征和纳米力学性能，并将结果与传统混凝土的ITZ进行比较。结果表明，传统混凝土的ITZ表现出带有孔隙和微裂纹的薄弱区域，而地聚合物混凝土的微观结构在骨料附近并未呈现出薄弱的ITZ区域。在传统混凝土的ITZ中观察到了更多的孔隙和裂纹。此外，还观察到相当数量的粉煤灰颗粒，这些颗粒在基体相中似乎未发生反应或仅部分反应。基于纳米压痕结果，58%的微观结构由未反应或部分反应的粉煤灰颗粒组成。纳米和微观尺度试验的结果将增进对混凝土在宏观尺度下的性能表现的理解。
