80℃蒸汽养护条件下外掺MgO膨胀剂三级配混凝土的膨胀

Expansion of three-graded concrete containing MgO expansive agent cured by 80 ℃ steam

在80℃蒸汽养护条件下,粗骨料粒径为5～20 mm、20～40 mm、40～80 mm三级配MgO混凝土试件的膨胀。结果表明,80℃蒸汽养护条件下,三级配MgO混凝土试件,28 d前膨胀快之后膨胀放缓,90 d时膨胀趋于稳定。MgO膨胀剂的活性越高,MgO混凝土试件最终产生的膨胀越小。粉煤灰降低掺低活性MgO膨胀剂混凝土试件膨胀,而对掺高活性MgO膨胀剂的膨胀影响较小。

Concrete specimens containing MgO-based expansive agent （MEA） were prepared byusing aggregates with particle sizes of5-20 mm, 20-40 mm and 40-80 mm, and then cured by 80 ℃ steam,The expansions of the 80 ℃ steam cured concrete specimens were investigated at dif- ferent ages.Results showed that,the expansion curves of concrete specimens containing MEA grew fast within 28 d, and then it slowed down.At 90 d, all the expansion curves leveled off.The more reactive MEA added in the concrete, the smaller expansion was caused.In addition, for the MEA with low reactivity,the addition of fly ash contributed to a decrease in the expansion of concrete,whereas it has no obvious influence on the ex- pansion of concrete incoporating MEA with high reactivity.