碳纤维改性地聚物的力学特性及微观形貌

Mechanical Properties and Micro-morphology of Carbon-fiber Modified Geopolymer

地聚物以三维网状结构的硅铝酸盐胶凝形式存在,具有优异的力学性能、热稳定性、耐高温及耐腐蚀等特性。为充分利用循环流化床粉煤灰和炉底渣、提升粉煤灰/炉底渣基地聚物的力学特性,特别是断裂韧性,研究碳纤维改性地聚物的力学特性和微观形貌,采用万能材料试验机及场发射扫描电镜分别分析碳纤维改性地聚物的力学特性和微观形貌。通过改变碳纤维掺量和碱激发剂种类评价碳纤维对地聚物断裂韧性、抗压强度及微观结构的影响。当碳纤维掺量为8%、氢氧化钾和硅酸钠复合碱激发时,地聚物断裂韧性达到最大值6.23 MPa·m^(1/2)。结果表明:粉煤灰/炉底渣基地聚物反应活性较低,需要加入高活性的碱激发剂或高活性的反应物;掺入碳纤维可显著改善地聚物的力学特性,特别是地聚物的断裂韧性。碳纤维的量与地聚物断裂韧性呈抛物线关系,地聚物断裂韧性先增大后减少。

Geopolymers exist in the form of aluminosilicate gels with a three-dimensional network structure,which has excellent mechanical properties,such as thermal stability,high temperature resistance and corrosion resistance and so on.In order to make full use of the circulating fluidized bed fly ash and furnace bottom slag,and improve the mechanical properties of the fly ash and furnace bottom slag-based geopolymer(FBG),especially the fracture toughness,the mechanical properties and micro morphology of carbon-fiber modified geopolymers(CMG)were investigated.A universal material testing machine and scanning electron microscope were used to analyze the mechanical properties and micromorphology of CMG.The effects of carbon-fiber on fracture toughness,compressive strength and micro-structure of geopolymers were evaluated by changing the amount of carbon fiber and the type of alkali activator.The fracture toughness of the geopolymer reaches a maximum of 6.23 MPa·m^(1/2),when the content of carbon-fiber is 8%and the complex alkali of potassium hydroxide and sodium silicate is excited.The results show that the reactivity of FBG is low,and it is necessary to add a highly active alkali activator or a highly reactive reactant.The incorporation of carbon-fibers can significantly improve the mechanical properties of geopolymers,especially in fracture toughness.The content of carbon-fiber has a parabolic relationship with the fracture toughness of the geopolymer.The fracture toughness of the geopolymer increases first and then decreases.