湿筛对掺MgO膨胀剂混凝土安定性评价的影响

Influences of Wet Screening on Soundness Evaluation of Concrete with MgO Expansive Agents

在80℃加速养护条件下,采用数据采集系统连续测定掺MgO膨胀剂(MEA)三级配混凝土、湿筛二级配混凝土和湿筛一级配混凝土试件的膨胀率,结合混凝土的劈裂抗拉强度和微观结构来评价掺MEA混凝土的安定性。结果表明:三级配混凝土、湿筛二级配混凝土和湿筛一级配混凝土中MEA的极限掺量分别为12%、10%和8%,掺MEA湿筛二级配混凝土和湿筛一级配混凝土的安定性评定并不能反映三级配混凝土试件的安定性,采用实际配合比混凝土来评定MEA的安定性更能反映实际情况。

The soundness of the three graded, wet screened two graded and wet screened one graded concrete specimens with MgO expansive agent （MEA） was evaluated by combination of expansion, splitting tensile strength and microstructure. The results demonstrate that the limit of MEA in the three graded, wet screened two graded and wet screened one graded concrete was 12%, 10 %and 8%, respectively. The soundness of wet screened two graded or wet screened one graded concrete does not represent soundness of the three graded concrete. Therefore, the soundness of concrete specimens contained MEA should be evaluated by the practical mix proportion used in the engineering.