Schneider Nick, Stephan Dietmar
Building Material and Construction Chemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, Berlin 13355, Germany.
Materials (Basel). 2016 Mar 7;9(3):174. doi: 10.3390/ma9030174.
An effective retarded suspension of ground granulated blast-furnace slag (GGBFS) needs a strong activator to reactivate the hydration. In this research study, sodium hydroxide (NaOH) as an alkali activator in two different concentrations (30 and 50 wt.%) was used to overcome the retardation and give the hardened GGBFS the reasonable strength. The study was carried out with a mixture of GGBFS, a solution of 1.0 wt.% d-gluconic acid (C₆HO₇) as a retarder in the mixing water and a methyl cellulose as a stabilizer. The reactivation was executed after seven different periods (up to 28 days) after the system was retarded. The following investigations were performed: slump test, measurement of ultrasonic (US) velocity, compressive strength and gross density, thermogravimetry (TG) and scanning electron microscopy (SEM). The analyses of the hardened samples were carried out seven, 28 and 90 days after the reactivation. The result of the study is an effective reactivation of a retarded suspension. In this case, the activator with 50 wt.% NaOH shows a very high performance. The setting time of the reactivated binders is much longer compared to the reference, but, in the longer term, the compressive strength and the progress of the hydration exceed the performance of the reference.
有效的磨细粒化高炉矿渣（GGBFS）缓凝悬浮液需要一种强活化剂来重新激发水化作用。在本研究中，使用两种不同浓度（30 wt.%和50 wt.%）的氢氧化钠（NaOH）作为碱性活化剂，以克服缓凝作用，并使硬化后的GGBFS具有合理的强度。该研究采用GGBFS、在拌合水中作为缓凝剂的1.0 wt.% d -葡萄糖酸（C₆H₁₂O₇）溶液以及作为稳定剂的甲基纤维素的混合物进行。在系统缓凝后的七个不同时间段（最长28天）后进行再活化。进行了以下研究：坍落度试验、超声波（US）速度测量、抗压强度和毛体积密度、热重分析（TG）和扫描电子显微镜（SEM）。在再活化后的7天、28天和90天对硬化样品进行分析。研究结果是对缓凝悬浮液进行了有效的再活化。在这种情况下，50 wt.% NaOH的活化剂表现出非常高的性能。与参比物相比，再活化胶凝材料的凝结时间长得多，但从长期来看，抗压强度和水化进程超过了参比物的性能。
