Xie Lilan, Liu Kaiwei
School of Materials and Architectural Engineering, Guizhou Normal University, Guiyang 550001, China.
Anhui Province Engineering Laboratory of Advanced Building Materials, Anhui Jianzhu University, Hefei 230601, China.
Materials (Basel). 2022 Feb 24;15(5):1687. doi: 10.3390/ma15051687.
Delayed strength development and long setting times are the main disadvantageous properties of NaCO-activated slag cements. In this work, combined auxiliary activators of Ca(OH) and Mg(OH) were incorporated in one-part NaCO-activated slag binders to accelerate the kinetics of alkali activation. The properties and microstructure evolution were investigated to clarify the reaction mechanism. The results showed that the additions of auxiliary activators promoted the hardening of the pastes within 2 h. The 28 days compressive strengths were in the range of 39.5-45.5 MPa, rendering the binders practical cementitious materials in general construction applications. Ca(OH) was more effective than Mg(OH) in accelerating the kinetics of alkali activation. The dissolution of Ca(OH) released more OH and Ca ions in the aqueous phase to increase alkalinity in the aqueous phase and promote the formation of the main binding gel phase of calcium-aluminosilicate hydrate (C-A-S-H). An increase in the Ca(OH)/Mg(OH) ratios increased autogenous shrinkage and decreased drying shrinkage of the binders. The formation of a compact pore structure restricted the water evaporation from the binders during the drying procedure.
强度发展延迟和凝结时间长是碳酸钠激发矿渣水泥的主要不利性能。在本研究中，将氢氧化钙（Ca(OH)）和氢氧化镁（Mg(OH)）复合助激发剂掺入单组分碳酸钠激发矿渣胶凝材料中，以加速碱激发动力学。通过研究性能和微观结构演变来阐明反应机理。结果表明，添加助激发剂促进了浆体在2小时内的硬化。28天抗压强度在39.5 - 45.5MPa范围内，使该胶凝材料成为一般建筑应用中的实用胶凝材料。氢氧化钙在加速碱激发动力学方面比氢氧化镁更有效。氢氧化钙的溶解在水相中释放出更多的氢氧根离子（OH）和钙离子（Ca），以提高水相碱度并促进钙铝硅酸盐水合物（C-A-S-H）主要结合凝胶相的形成。氢氧化钙与氢氧化镁比例的增加会增加胶凝材料的自收缩并降低干燥收缩。致密孔结构的形成限制了干燥过程中胶凝材料的水分蒸发。
