School of Engineering , Newcastle University , Newcastle Upon Tyne NE1 7RU , U.K.
Condensed Matter Physics Department , University of the Basque Country (UPV/EHU) , Bilbao 48940 , Spain.
ACS Appl Mater Interfaces. 2018 Jul 5;10(26):22809-22820. doi: 10.1021/acsami.8b03873. Epub 2018 Jun 25.
Geopolymers are hydrated aluminosilicates with excellent binding properties. Geopolymers appeal to the construction sector as a more sustainable alternative to traditional cements, but their exploitation is limited by a poor understanding of the linkage between chemical composition and macroscopic properties. Molecular simulations can help clarify this linkage, but existing models based on amorphous or crystalline aluminosilicate structures provide only a partial explanation of experimental data on the nanoscale. This paper presents a new model for the molecular structure of geopolymers, in particular for nanoscale interfacial zones between crystalline and amorphous nanodomains, which are crucial for the overall mechanical properties of the material. For a range of Si-Al molar ratios and water contents, the proposed structures are analyzed in terms of skeletal density, ring structure, pore structure, bond-angle distribution, bond length distribution, X-ray diffraction, X-ray pair distribution function, elastic moduli, and large-strain mechanics. Results are compared with experimental data and with other simulation results for amorphous and crystalline molecular models, showing that the newly proposed structures better capture important structural features with an impact on mechanical properties. This offers a new starting point for the multiscale modeling of geopolymers.
水硬铝硅酸盐具有优异的结合性能，因此被称为地质聚合物。作为传统水泥的替代品，地质聚合物在建筑行业具有很大吸引力，因为其更加环保，但由于对化学成分与宏观性能之间的联系缺乏深入了解，其应用受到限制。分子模拟有助于阐明这种联系，但基于无定形或结晶铝硅酸盐结构的现有模型只能对纳米尺度上的实验数据提供部分解释。本文提出了一种新的地质聚合物分子结构模型，特别是针对结晶和无定形纳米畴之间的纳米级界面区域的结构模型，因为这些区域对材料的整体力学性能至关重要。针对一系列 Si-Al 摩尔比和含水量，本文从骨架密度、环结构、孔结构、键角分布、键长分布、X 射线衍射、X 射线对分布函数、弹性模量和大应变力学等方面对所提出的结构进行了分析。结果与实验数据和其他用于无定形和结晶分子模型的模拟结果进行了比较，表明新提出的结构能够更好地捕捉对力学性能有影响的重要结构特征。这为地质聚合物的多尺度建模提供了一个新的起点。
