Beijing Bioprocess Key Laboratory, Beijing University of Chemical Technology, Beijing, 100029, PR China.
State Key Laboratory of Special Functional Waterproof Materials, Beijing Oriental Yuhong Waterproof Technology Co. Ltd, Beijing, 101309, PR China.
J Environ Manage. 2020 May 1;261:110225. doi: 10.1016/j.jenvman.2020.110225. Epub 2020 Mar 2.
Concrete is significant for construction. A problem in application is the appearance of cracks that will damage its strength. An autogenous crack-healing mechanism based on bacteria receives increasing attention in recent years. The bacteria are able to form calcium carbonate (CaCO) precipitations in suitable conditions to protect and reinforce the concrete. However, a large number of spores are crushed in aged specimens, resulting in a loss of viability. A new kind of hydrogel crosslinked by alginate, chitosan and calcium ions was introduced in this study. It was observed that the addition of chitosan improved the swelling properties of calcium alginate. Opposite pH response to calcium alginate was observed when the chitosan content in the solution reached 1.0%. With an addition of 1.0% chitosan in hydrogel beads, 10.28% increase of compressive strength and 13.79% increase of flexural strength to the control were observed. The results reveal self-healing properties of concretes. A healing crack of 4 cm length and 1 mm width was observed when using cement PO325, with the addition of bacterial spores (2.54-3.07 × 10/cm concrete) encapsulated by hydrogel containing no chitosan.
混凝土在建筑中很重要。在应用中存在一个问题，即会出现裂缝，从而损坏其强度。近年来，基于细菌的自生裂缝愈合机制受到越来越多的关注。在适当的条件下，细菌能够形成碳酸钙（CaCO）沉淀，从而保护和增强混凝土。然而，在老化的标本中，大量孢子被压碎，导致其丧失活力。在本研究中引入了一种由藻酸盐、壳聚糖和钙离子交联的新型水凝胶。观察到壳聚糖的添加改善了钙藻酸盐的溶胀性能。当溶液中的壳聚糖含量达到 1.0%时，观察到与钙藻酸盐相反的 pH 响应。在水凝胶珠中添加 1.0%的壳聚糖，抗压强度增加了 10.28%，抗弯强度增加了 13.79%，与对照组相比。结果显示了混凝土的自愈合性能。当使用水泥 PO325 并添加细菌孢子（2.54-3.07×10/cm 混凝土）时，观察到了长度为 4 cm、宽度为 1 mm 的愈合裂缝，这些孢子被含有壳聚糖的水凝胶包裹。
