等强度下混凝土组分对徐变性能的影响

Influence of concrete constituents on creep characteristics of concrete at same compressive strengths

采用自制的徐变加载装置,研究了聚乙烯醇(PVA)纤维、双掺粉煤灰和矿渣以及减缩剂对7d等强度混凝土徐变性能的影响规律,结合与混凝土同水胶比浆体的化合结合水量分析了其影响机理。结果表明,混凝土徐变系数发展较快,加载100d左右趋于稳定;减缩剂和双掺矿物掺合料均明显降低了混凝土的徐变系数,以掺减缩剂效果更好,450d值仅为0.63,而PVA纤维增加了徐变系数;混凝土的徐变系数随浆体化学结合水量的增加而降低,60d早龄期浆体水化有利于降低徐变系数,450d后期水化产物对降低混凝土的徐变系数贡献不大。

The influence law of polyvinyl alcohol（PVA） fiber,shrinkage reducing admixture（SRA） and the combined addition of fly ash and slag on creep characteristics of concrete with 7d same compressive strengths were studied by the self-made creep loading device and the influence mechanism were analyzed by testing chemically combined water of paste with same water-binder ratio with concrete.The results indicate that creep coefficients develop rapidly,becoming stable after 100d＇ loading;SRA and the combined addition of fly ash and slag significantly reduce creep coefficients of concrete,the better effect with SRA,the value of 450d only being 0.63,but PVA fiber increases creep coefficient,not suitable to produce concrete for high speed railway;creep coefficients of concrete decrease with the rise of chemically combined water of paste,and hydration at 60d early ages is in favor of reducing creep coefficients but hydrated products at 450d later ages can not make contribution to reducing creep coefficients.