Sitarz Mateusz, Castro-Gomes João, Hager Izabela
Chair of Building Materials Engineering, Faculty of Civil Engineering, Cracow University of Technology, 31-155 Cracow, Poland.
Centre of Materials and Building Technologies (C-MADE), Department of Civil Engineering and Architecture, University of Beira Interior (UBI), 6201-001 Covilhã, Portugal.
Materials (Basel). 2021 Dec 28;15(1):211. doi: 10.3390/ma15010211.
Mineral geopolymer binders can be an attractive and more sustainable alternative to traditional Portland cement materials for special applications. In geopolymer technology the precursor is a source of silicon and aluminium oxides, the second component is an alkaline solution. In the synthesis of geopolymer binders the most commonly used alkaline solution is a mixture of sodium or potassium water glass with sodium or potassium hydroxide or silicate solution with a low molar ratio, which is more convenient and much safer in use. In this paper, we present the influence of sodium or potassium silicate solution on the physical and mechanical properties of fly ash and ground granulated blast furnace slag-based geopolymer mortars. Mercury intrusion porosimetry and microstructural observation allowed for comparing the structure of materials with a different type of alkaline solution. The evolution of compressive and flexural tensile strength with time determined for composites using 10%, 30% and 50% slag contents (referring to fly ash mass) was analysed. The tests were performed after 3, 7, 14 and 28 days. It was observed that, as the amount of slag used increases in the precursor, the strength of the material grows. Mortars with the sodium alkaline solution were characterised by a higher strength at a young age. However, the values of strength 28 days were higher for geopolymers with potassium alkaline solution reaching 75 MPa in compression. Geopolymer mortar microstructure observation indicates a high matrix heterogeneity with numerous microcracks. Matrix defects may be caused by the rapid kinetics of the material binding reaction or shrinkage associated with the drying of the material.
对于特殊应用而言，矿物地质聚合物粘结剂可以成为传统波特兰水泥材料颇具吸引力且更具可持续性的替代品。在地质聚合物技术中，前驱体是硅和铝氧化物的来源，第二种成分是碱性溶液。在地质聚合物粘结剂的合成中，最常用的碱性溶液是钠或钾水玻璃与氢氧化钠或氢氧化钾的混合物，或者是低摩尔比的硅酸盐溶液，其使用起来更方便且更安全。在本文中，我们展示了硅酸钠或硅酸钾溶液对粉煤灰和磨细粒化高炉矿渣基地质聚合物砂浆物理和力学性能的影响。压汞法孔隙率测定和微观结构观察有助于比较使用不同类型碱性溶液的材料结构。分析了使用10%、30%和50%矿渣含量（相对于粉煤灰质量）的复合材料抗压强度和抗弯抗拉强度随时间的变化情况。试验在3天、7天、14天和28天后进行。观察到，随着前驱体中矿渣用量的增加，材料强度提高。含钠碱性溶液的砂浆在早期具有较高的强度。然而，含钾碱性溶液的地质聚合物在28天时的强度值更高，抗压强度达到75MPa。地质聚合物砂浆微观结构观察表明，基体具有高度不均匀性且存在大量微裂纹。基体缺陷可能是由材料粘结反应的快速动力学或与材料干燥相关的收缩引起的。
