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自收缩已经成为配制高性能混凝土的一个重要考虑因素。自收缩引起的拉应力超过混凝土的抗拉强度时,混凝土就会产生裂缝,进而降低了混凝土的耐久性。Neville提出当混凝土的有效水胶比低于0.42时,必须从外界补充水分以避免其内部的自干燥,而高性能混凝土的水胶比远低于0.42,所以只有通过养护才能消除自收缩产生的不利变形。高吸水性树脂(SAP)是一种功能性高分子材料,具有很强的吸水特性,且吸水膨胀后生成的凝胶具有较好的保水性,可作为混凝土内养护剂。本文主要从SAP的合成方法,SAP作为内养护剂的作用机理,SAP对混凝土的力学性能、耐久性、收缩性能的影响进行综述。
Self-shrinking has become an important consideration in the formulation of high performance concrete. Since the tensile stress caused by the shrinkage exceeds the tensile strength of the concrete, the concrete cracks and the durability of the concrete is reduced. Neville proposed that when the effective water-cement ratio of concrete is less than 0.42, water must be replenished from the outside to avoid its internal self-drying, while the water-cement ratio of high-performance concrete is far below 0.42 so that self-shrinkage can be eliminated only after curing Adverse deformation. Superabsorbent polymer (SAP) is a kind of functional polymer material, which has strong water absorption property. And the gel formed after water absorption expansion has better water retention, and can be used as curing agent in concrete. This article mainly reviewed the synthesis methods of SAP, the mechanism of SAP as the internal curing agent, the influence of SAP on the mechanical properties, durability and shrinkage of concrete.