Guo Shuaicheng, Forooshani Pegah Kord, Dai Qingli, Lee Bruce P, Si Ruizhe, Wang Jiaqing
Associate Professor, Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province, College of Civil Engineering, Hunan University, Changsha, 410082, P. R. China & International Science Innovation Collaboration Base for Green & Advanced Civil Engineering Materials of Hunan Province, Hunan University, Changsha, 410082, P. R. China.
Research Assistant, Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931-1295.
Compos B Eng. 2020 Oct 15;199. doi: 10.1016/j.compositesb.2020.108262. Epub 2020 Jul 31.
The crack development is considered to be one of the most severe threats to the durability of concrete infrastructure. This study aims to enhance the durability performance of cementitious material with the pH-responsive Superabsorbent Polymer (SAP). The SAP was synthesized with acrylic acid (AA)-methyl acrylate (MA) precursors, and three type samples with different crosslinking levels were prepared. The examination on the pH sensitivity indicated that the swelling capacity of the prepared SAP would first increase and then decrease with solution alkalinity, and the peak swelling potential was achieved around pH value of 12 for all the three type SAP with solution/gel mass ratio of 500. Further examination indicated the alkalinity of the buffer solution was reduced during the adsorption test, which can be caused by the hydrolysis of the amide groups and the crosslinker. Besides that, it was also found the solution/gel ratio and the Ca(OH) content could affect the swelling potential of the SAP. After that, the performance tests were conducted for the evaluation of concrete with SAP. A wax-coating protocol for the SAP was designed by using the hot-water method to prevent its swelling during mixing process. It was found that the strength reduction for samples with wax-coated SAP was insignificant compared to that of the control samples. Furthermore, durability tests supported the wax-shell could be broken by the crack propagation in concrete. And further experimental studies are needed to optimize the wax-size and shell thickness for enhanced self-sealing efficiency.
裂缝发展被认为是对混凝土基础设施耐久性最严重的威胁之一。本研究旨在通过pH响应型高吸水性聚合物（SAP）提高胶凝材料的耐久性。采用丙烯酸（AA）-丙烯酸甲酯（MA）前驱体合成了SAP，并制备了三种不同交联程度的样品。对pH敏感性的研究表明，制备的SAP的溶胀能力会随着溶液碱度的增加先增大后减小，对于溶液/凝胶质量比为500的所有三种类型的SAP，在pH值约为12时达到最大溶胀潜力。进一步研究表明，在吸附试验过程中缓冲溶液的碱度降低，这可能是由于酰胺基团和交联剂的水解所致。除此之外，还发现溶液/凝胶比和Ca(OH)含量会影响SAP的溶胀潜力。之后，对含有SAP的混凝土进行性能测试以进行评估。采用热水法设计了一种用于SAP的蜡涂覆方案，以防止其在搅拌过程中溶胀。结果发现，与对照样品相比，涂蜡SAP样品的强度降低不明显。此外，耐久性测试表明蜡壳会因混凝土中的裂缝扩展而破裂。需要进一步的实验研究来优化蜡的尺寸和壳厚度，以提高自密封效率。
