纳米二氧化硅负载丙烯酰胺型SAP内养护性能研究

Internal Curing Properties of Acrylamide Type SAP Loaded with Nano Silica

设计制备了纳米二氧化硅(NS)负载丙烯酰胺型高吸水树脂(SAP),探究了不同NS负载量的SAP对砂浆自收缩、干燥收缩和力学性能的影响。结果表明,丙烯酰胺型SAP能够完全消除砂浆自收缩,而随着NS负载量增加,负载型SAP对自收缩的抑制作用降低,但仍保持在80%以上。SAP及额外水的引入增加了砂浆的干燥收缩,但随着NS负载量增加,负载型SAP对缓解干燥收缩有积极作用。SAP及额外水的引入降低了砂浆的力学性能,但随着NS负载量增加,负载型SAP显著改善了砂浆的力学性能。其中,负载50%(相对于丙烯酰胺的质量分数)NS的SAP对砂浆力学性能影响最小,试样在28 d龄期的抗压强度与抗折强度仅损失5.6%与2.2%。热重(TG)以及背散射扫描电子显微镜(BSE)结果表明,随着NS负载量增加,负载型SAP内养护试样的水化程度显著提高,微观结构明显改善。

In this paper,nano silica(NS)loaded acrylamide-type superabsorbent polymer(SAP)was designed and prepared,and the influence of different NS loadings of SAP on the autogenous shrinkage,drying shrinkage,and mechanical properties of mortar were investigated.The results showed that acrylamide-type SAP could completely eliminated the autogenous shrinkage of mortar,and the inhibition effect of NS-loaded SAP on autogenous shrinkage decreased with the increase of NS loading,but still remained above 80%.The introduction of SAP and additional water increased the drying shrinkage of mortar,but with the increase of NS loading,NS-loaded SAP had a positive effect on mitigating the drying shrinkage.The introduction of SAP and additional water reduced the mechanical properties of the mortar,but with the increase of NS loading,the NS-loaded SAP significantly improved the mechanical properties of mortar.In particular,SAP loaded with 50%(relative to the mass fraction of acrylamide)NS had the least effect on the mechanical properties of the mortar,with only a 5.6%and 2.2%loss in compressive and flexural strength of the specimens at 28 d.TG and BSE results showed that the degree of hydration of the cured specimens within NS-loaded SAP increased significantly with the increase of NS loading,and the microstructure was significantly improved.