Department of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.
Department of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.
J Colloid Interface Sci. 2019 Mar 7;538:397-403. doi: 10.1016/j.jcis.2018.12.004. Epub 2018 Dec 3.
Superabsorbent polymers (SAPs) are broadly applied in cement and concrete. However, the increased macrovoids resulting from the absorption/desorption of SAPs, remarkably reduced the resulting mechanical properties. In this study, we prepared superabsorbent CaAlg hydrogels by crosslinking Ca and sodium alginate (NaAlg). The ion-responsive behavior of CaAlg was measured, and results showed at lower the Ca concentrations, higher swelling potentials were observed, which was consistent with what was expected with the formation of a less dense network. This interesting dependence on Ca concentration likely avoids the formation of large macro-pores during the mixing process of cement and results in increased swelling when cracks occur and water enters the crevices. The results of compressive strength measurements demonstrated that the addition of 0.5 wt% CaAlg resulted in a negligible reduction (0.014%) in compressive strength due to the limited swelling capacity in pore solution. Interestingly, in the sodium silicate self-healing system, in addition to the widely reported self-sealing effects upon adsorption of additional water, CaAlg also accelerates the precipitation of calcium silicate hydrates (CSH) by providing Ca, which makes the healing process more efficient.
高吸水性聚合物（SAP）在水泥和混凝土中得到广泛应用。然而，SAP 的吸收/解吸所导致的宏观空隙的增加，显著降低了其力学性能。在这项研究中，我们通过交联钙和海藻酸钠（NaAlg）制备了高吸水性 CaAlg 水凝胶。测量了 CaAlg 的离子响应行为，结果表明在较低的 Ca 浓度下，观察到更高的溶胀势，这与预期的形成密度较低的网络一致。这种有趣的 Ca 浓度依赖性可能避免了在水泥混合过程中形成大的宏观孔隙，并导致在出现裂缝和水进入裂缝时发生更大的溶胀。抗压强度测量结果表明，由于在孔隙溶液中的溶胀能力有限，添加 0.5wt% CaAlg 仅导致抗压强度可忽略不计的降低（0.014%）。有趣的是，在硅酸钠自修复体系中，除了广泛报道的在吸附额外水时的自修复效果之外，CaAlg 还通过提供 Ca 来加速硅酸钙水合物（CSH）的沉淀，这使得修复过程更有效。
