高温养护和粉煤灰掺量对外掺氧化镁混凝土膨胀和劈裂抗拉强度的影响

Effect of Curing at High Temperatures and Content of Fly Ash on the Expansion and Split-tensile Strength of Concrete Mixed with MgO

主要研究了不同温度加速养护条件下,掺入不同量MgO膨胀剂和粉煤灰的混凝土试件的膨胀性能和劈裂抗拉强度,明确高温养护对外掺MgO混凝土膨胀与劈拉强度的影响规律。结果表明,随着养护温度的升高,混凝土的膨胀将加快,膨胀曲线趋于平缓的时间就越短;MgO掺量的增加不仅使混凝土的膨胀值增大,而且对其劈拉强度造成影响。适当掺量的MgO可能使混凝土劈拉强度有所增加,当MgO掺量过大时,则对混凝土劈拉强度没有贡献,甚至可能使其强度降低;粉煤灰对MgO的膨胀有明显的抑制作用,提高了高掺量MgO混凝土的劈裂抗拉强度。

The effects of curing temperature in accelerated experiment on the expansion and splitting-tensile strength of concrete containing different contents of MgO-based expansive agent（MEA） and fly ash are investigated.Results show that the expansion curves of concrete specimens ascended more rapidly and leveled off within shorter age when cured under higher temperature.The expansion of concrete specimen increase with the increasing addition of MEA.The splitting-tensile strength of concrete could be improved when added with proper dosage of MEA,but it may also be reduced when excessive MEA is added.The expansion could be inhibited to an extent by the addition of fly ash,which may improve the splitting tensile strength of concrete.