粉煤灰基地质聚合物力学性能及碱渣改性机理

Mechanical Properties of Fly Ash-based Geopolymers and Modification Mechanism of Soda Residue

为探索粉煤灰基地质聚合物的力学特性,通过12组胶砂试样的抗折和抗压强度研究NaOH掺量、养护条件、龄期和碱渣掺量对力学性能的影响,对比不同因素下试样胶砂表面孔隙特征,分析了碱渣对粉煤灰基地质聚合物体系的改性机理。结果表明:1.NaOH溶液过剩使强度降低;高温养护能提高强度;粉煤灰基地质聚合物的养护不需要太大的湿度。2.碱渣掺量小于27%时,对粉煤灰-NaOH体系强度有显著的改性作用。CaCO_3增大溶液碱性,减小胶砂流动性,影响地质聚合物的微观结构,有效改善体系收缩程度。3.可溶性含钙组分中Ca^(2+)参与生成C-SH凝胶,与地质聚合物协同作用提高胶结性,减小孔隙的连通性。

To explore the mechanism properties of the fly ash based geopolymers,the flexural and compressive strengths of 12 groups of mortar samples were conducted to research the effects of NaOH solution content,curing conditions,curing age and soda residue content on the mechanical properties. And the surface porosity characteristics of mortar were compared from different factors. The soda residuemodified mechanism was analyzed. Results show that an excess of NaOH solution content can reduce the mortar strengths. Higher curing temperature can improve the strength. Fly ash-based geopolymer does not need too much humidity. When its content is less than 27%,soda residue has a significantly modified role. For the fly ash-sodium hydroxide mortar system,carbonate calcium can increase alkalinity of solution,decrease fluidity,impact the geopolymers＇ microstructure and effectively improve the shrinkage.Calcium ions in soluble calcium components,such as CaCl_2 and Ca（ OH）_2,are involved in generating CS-H gel which works jointly with geopolymers to improve the cement and pore connectivity.