高性能膨胀混凝土水胶比较低,膨胀剂因混凝土内部缺少足够的水分而不能充分反应。内养护技术的出现实现了从内部为混凝土补水,在混凝土中掺入适量的高分子吸水性树脂(SAP),让其从内部为混凝土提供水分,既可为膨胀剂反应提供水分,又达到内养护的双重效果。通过试验研究了SAP的掺量对膨胀混凝土力学性能和孔隙结构的影响。试验结果表明:掺量为0.3%的SAP对膨胀混凝土力学性能的改善效果最好,混凝土强度提高5.4%;适量SAP的掺入可以改善膨胀混凝土内部孔隙结构,提高膨胀剂与混凝土有关组分反应的充分性,同时促进水泥二次水化,使得混凝土内部孔隙变小、结构更加致密;但是,当掺量超过0.3%时,SAP会在混凝土内部产生不利的孔隙,致使强度降低。研究结果可为膨胀混凝土内养护提供科学依据。

Expansion agent cannot fully react due to the lack of sufficient moisture inside high-performance expansive concrete. Superabsorbent polymer (SAP) provides the expansion agent reaction with sufficient moisture, and also supports the internal curing of concrete. In this paper, the effects of SAP dosage on mechanical properties and pore structure of expansive concrete are studied via experimental approach. Test results demonstrate that the dosage of SAP as of 0.3% brings about a maximum improvement of mechanical properties of expansive concrete and a surging of concrete’s strength by 5.4%. A proper amount of SAP also improves the internal pore structure of expansive concrete and enhances the reaction between expansion agent and concrete’s compositions; and in the meantime, SAP shrinks the pores in concrete, and condenses concrete’s structure by stimulating cement’s secondary hydration. Nevertheless, the dosage of SAP exceeding 0.3% generates unfavorable pores inside the concrete, resulting in a decrease in strength.