Morinaga Yuka, Akao Yuya, Fukuda Daisuke, Elakneswaran Yogarajah
Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
Industrial & Household Chemicals Research Department, Industrial & Household Solutions Division, Nippon Shokubai, Osaka 564-0034, Japan.
Materials (Basel). 2022 Apr 7;15(8):2727. doi: 10.3390/ma15082727.
Superabsorbent polymers (SAPs) are used as internal curing agents in cementitious materials, which reduce autogenous shrinkage in concrete as they have a low water-to-cement ratios and improve the freeze-thaw resistance. However, the compressive strength of concrete may also be reduced due to additional voids in the hydrated cement matrix. In this study, we fabricated a delayed absorption type of SAP (I-SAP) composed of cross-linked modified acrylate and studied its absorption characteristics and effect on compressive strength after 28 days. Furthermore, the effect of curing conditions on the strength of concrete and hydrated cement paste with SAP were investigated. The absorption capacity of I-SAP in the synthetic pore solution and deionised water was examined and compared with that of a conventional SAP, and the former was absorbed more by I-SAP. The results revealed that the compressive strength of concrete increased with the addition of I-SAP, particularly with the curing condition of 60% RH. Although the compressive strength of hydrated cement paste with I-SAP reduced in water or sealed curing conditions, no loss of strength in the paste cured at 60% RH was seen. The cement matrix densification due to hydration of belite around the SAP surface is the main mechanism for strength development in concrete cured at sealed and 60% RH. However, the voids formed by SAP control the compressive strength of hydrated paste.
高吸水性聚合物（SAPs）被用作胶凝材料中的内部养护剂，由于其水灰比低，可减少混凝土的自收缩，并提高抗冻融性。然而，由于水化水泥基体中存在额外的孔隙，混凝土的抗压强度也可能会降低。在本研究中，我们制备了一种由交联改性丙烯酸酯组成的延迟吸收型SAP（I-SAP），并研究了其吸收特性以及对28天后抗压强度的影响。此外，还研究了养护条件对含有SAP的混凝土和水化水泥浆体强度的影响。考察了I-SAP在合成孔溶液和去离子水中的吸收能力，并与传统SAP进行了比较，结果发现I-SAP对前者的吸收更多。结果表明，添加I-SAP可提高混凝土的抗压强度，特别是在相对湿度为60%的养护条件下。虽然含有I-SAP的水化水泥浆体在水中或密封养护条件下抗压强度降低，但在相对湿度为60%的条件下养护的浆体未见强度损失。在密封和相对湿度为60%的条件下养护的混凝土中，由于贝利特在SAP表面水化导致水泥基体致密化是强度发展的主要机制。然而，由SAP形成的孔隙控制着水化浆体的抗压强度。
