Frost Resistance of Marine Concrete in Cold Regions

1.北海道海工混凝土结垢损伤调查对1987年建成的11个混凝土结构进行了调查。主要研究结果如下。结垢深度最大为8.6 mm，结垢面积随年龄增长而变宽，结垢比例(结垢深度与结垢面积的乘积)在修复后1~2年进展较快。混凝土在潮汐或飞溅区暴露五到七年的性能。暴露在鄂霍次克海中的混凝土试件的暴露测试结果证实了以下结论。寒冷地区的海洋环境对混凝土有着极其苛刻的条件。硅灰掺量或掺量为8%的混凝土具有较好的抗结垢性能。飞溅区16年混凝土结垢可靠性分析尝试了混凝土结垢的可靠性评估理论。这些标本大小为1立方米，暴露在鄂霍次克海中。得出了以下结论。可靠度函数的威布尔分布符合不低于装配率的缩尺深度频率分布。在恒定安装比率下定标的50%可靠性的一年时间与测量结果一致。

1. Scaling Damage Survey of Marine Concrete in HokkaidoEleven concrete structures which were constructed in 1987 were investigated. The main results are as follows. The maximum depth of scaling was 8.6mm, the scaling area became wider with age, and the scaling ratio(the scaling depth multiplied by the scaling area) made rapid progress for the first one or two years after construction.2. Properties of Concrete Exposed to Tidal or Splash Zone for Five or Seven Years.The following were confirmed by the results of exposure test of concrete specimens which were exposed to the Sea of Okhotsk. Marine environment in cold regions has extremely severe conditions for concrete. Concrete which contained silica fume or eight percent air volume show good resistance to scaling.3. Reliability Analysis to Scaling of Concrete Exposed to Splash Zone for 16 Years.Reliability theory for assessing concrete scaling was attempted. The specimens were one cubic meter and were exposed to the Sea of Okhotsk. The following conclusions were drawn. Weible distribution for reliability function conformed to frequency distribution of scaling depth which were not lower than the set-up ratio. The year lapse of fifty percent reliability for scaling at the constant set-up ratio agreed with the measurements.