Tonelli Monica, Baglioni Piero, Ridi Francesca
Department of Chemistry "Ugo Schiff" & CSGI, University of Florence, Via della Lastruccia 3 Sesto Fiorentino, I-50019 Florence, Italy.
Materials (Basel). 2020 Jul 15;13(14):3150. doi: 10.3390/ma13143150.
The ingress of water, as a vehicle for many harmful substances, is the main cause of all the major physical and chemical degradation processes affecting concrete buildings. To prevent damage and protect concrete surfaces, coatings are generally used. Cement-based coatings in particular can act as a physical barrier and reduce the permeability of surfaces. In case of chloride-induced corrosion, corrosion inhibitors are also generally used, and nano-carriers have been proven to provide a long-term protective effect. In this work, we designed a surface protection cementitious coating enhanced with nano-silica and halloysite nanotubes (HNTs). HNTs were loaded with a corrosion inhibitor, benzotriazole (BTA), and used as nano-reservoir, while nano-silica was used to improve the structure of the protective coating and to strengthen its adhesion to the surface of application. The cementitious coatings were characterized with a multi-technique approach including thermal and spectroscopic analysis, scanning electron microscopy, specific surface area and pore size distribution, and Vickers hardness test. The release of BTA was monitored through UV-vis analysis, and the transportation of BTA through coated mortars was studied in simulated rain conditions. We evidenced that the presence of silica densifies the porous structure and increases the interfacial bond strength between the protective coating and the surface of application. We report here, for the first time, that HNTs can be used as nano-carriers for the slow delivery of anti-corrosion molecules in cement mortars.
水作为许多有害物质的载体，是影响混凝土建筑的所有主要物理和化学降解过程的主要原因。为防止损坏并保护混凝土表面，通常会使用涂层。特别是水泥基涂层可以起到物理屏障的作用，降低表面的渗透性。在氯离子引起的腐蚀情况下，通常也会使用缓蚀剂，并且已证明纳米载体可提供长期保护作用。在这项工作中，我们设计了一种用纳米二氧化硅和埃洛石纳米管（HNTs）增强的表面保护水泥基涂层。HNTs负载了缓蚀剂苯并三唑（BTA），用作纳米储库，而纳米二氧化硅则用于改善保护涂层的结构并增强其与应用表面的附着力。通过多种技术方法对水泥基涂层进行了表征，包括热分析和光谱分析、扫描电子显微镜、比表面积和孔径分布以及维氏硬度测试。通过紫外可见分析监测BTA的释放，并在模拟降雨条件下研究BTA通过涂层砂浆的传输。我们证明了二氧化硅的存在使多孔结构致密化，并增加了保护涂层与应用表面之间的界面结合强度。我们首次在此报告，HNTs可以用作纳米载体，用于在水泥砂浆中缓慢释放防腐分子。
