Influence of pore structure on the strength behavior of particle- and fiber-reinforced metakaolin-based geopolymer composites
Influence of pore structure on the strength behavior of particle- and fiber-reinforced metakaolin-based geopolymer composites
复制标题
DOI：
10.1016/j.cemconcomp.2019.103361
复制
发表时间：
2019-11-01
影响因子：
10.5
通讯作者：
Kriven, Waltraud M.
中科院分区：
文献类型：
--
作者：
Akono, Ange Therese;Koric, Seid;Kriven, Waltraud M.
地质聚合物是 X 射线非晶材料，具有高弯曲强度和高压缩强度等吸引人的特性。然而，异质性和孔隙率对本构行为的影响尚不完全清楚。我们制定了基于物理的多尺度力学模型来描述地质聚合物复合材料的强度行为。使用基于能量的方法，我们得出了新颖的解决方案来描述纤维增强和颗粒增强偏高岭土地质聚合物的有效屈服标准。我们使用纳米压痕测试校准我们的理论模型，并通过偏高岭土基地质聚合物复合材料的弯曲强度测试验证我们的理论框架。地质聚合物复合材料被发现表现出与压力相关的颗粒行为。我们将孔隙率细分为纳米孔隙率和微米孔隙率。我们的结果表明，纳米孔隙率仅受化学影响，而不受加工和增强材料的存在的影响。由于纳米孔隙度的存在，强度与总孔隙度的关系并不唯一。然而，强度和微孔率之间存在近似一一对应的关系。纳米颗粒结构和纳米尺度的化学成分对有效的机械响应具有深远的影响。我们的概念框架是地质聚合物复合材料行为机械建模的重要一步。
Geopolymers are X-ray amorphous materials with appealing properties such as high flexural strength and high compressive strength. Yet, the influence of the heterogeneity and porosity on the constitutive behavior is not fully understood. We formulate a multiscale physics-based mechanistic model to describe the strength behavior of geopolymer composites. Using an energy-based approach, we derive novel solutions to describe the effective yield criterion of fiber-reinforced and particle-reinforced metakaolin geopolymers. We calibrate our theoretical model using nanoindentation tests and validate our theoretical framework via flexural strength tests on metakaolin-based geopolymer composites. Geopolymer composites are found to exhibit a pressure-dependent granular behavior. We subdivide the porosity into nanoporosity and microporosity. Our results indicate that the nanoporosity is solely influenced by the chemistry and is not influenced by the processing and the presence of reinforcement. Due tothe presence of nanoporosity, the strength-total porosity relationships are not unique. However, an approximate one-to-one correspondence exists between the strength and the microporosity. The nanogranular structure and the chemical composition at the nanometer scale have a profound influence on the effective mechanical response.Our conceptual framework is an important step in the mechanistic modeling of the behavior of geopolymer composites.