含白云石微粉粉煤灰基地质聚合物的力学性能及微观结构

Mechanical Property and Microstructure of Fly Ash-Based Geopolymers with Dolomite Powders

研究了白云石粒径及掺量对以粉煤灰和偏高岭土为原料制备的地质聚合物抗压强度和微观结构的影响。结果表明:掺入10%～25%的白云石粉体有利于提高地质聚合物早期和后期抗压强度,粉体越细和掺量越多,早期增强效果越显著。热重分析表明加入白云石后降低地质聚合物中自由水、填隙水含量,提高结构水含量。微观结构研究显示白云石在地质聚合物中参与反应,其反应机制包括溶解-沉淀和扩散控制过程。白云石反应溶出的Ca、Mg与地质聚合物凝胶结合形成的致密的钙镁铝硅酸凝胶、白云石-凝胶基体之间良好的界面结合以及白云石微粉的微集料效应,共同促进了地质聚合物强度发展和提高。

Effect of adding dolomite particles with different sizes and amounts to geopolymer made using a mixture of fly ash and metakaolin as aluminosilicate sources was examined by compressive strength testing and microstructural study.Addition of 10%—25%of dolomite powders is beneficial to compressive strength.The finer the dolomite particle size and the more the mineral added,the higher the early and the final strength achieved.Thermogravimetry analysis indicated that the addition of dolomite could decrease the amount of free and interstitial water,while increasing structural water.Microstructure study showed that dolomite particles reacted with alkalis in which both dissolution-precipitation and diffusion-controlled processes were involved.The formation of Ca-Mg containing aluminosilcate gel,dense interfacial zone around dolomite particles as well as the micro-aggregate effect contributed to the strength enhancement of geopolymer with dolomite powders.