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Relationship between internal relative humidity and pore water saturation of dam concrete
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摘要: 为了研究大坝混凝土内部相对湿度100%和孔隙水饱和度100%是否具有唯一对应关系，成型了不同粉煤灰掺量（0、35%）的大坝二级配混凝土试件，通过温湿度传感器监测获得混凝土内部相对湿度，结合称重试验计算获得混凝土孔隙水饱和度。结果表明：绝湿状态下，水胶比0.5的大坝混凝土内部相对湿度始终为100%，然而对应的孔隙水饱和度并不一定为100%，不掺粉煤灰与掺35%粉煤灰的混凝土的孔隙水饱和度分别为85%~89%和73%~76%，即大坝混凝土孔隙水饱和度100%对应于内部相对湿度100%，而内部相对湿度100%不是唯一对应孔隙水饱和度100%。在绝湿状态下，水胶比0.5掺35%粉煤灰的混凝土的孔隙水饱和度要小于不掺粉煤灰的混凝土。Abstract: In order to investigate whether there is a unique correspondence between the relative humidity of 100% inside dam concrete and the pore water saturation of 100%, dam secondary concrete specimens with a water-binder ratio of 0.5 and different fly ash contents (0, 35%) were formed. The relative humidity inside the concrete specimens was monitored by temperature and humidity sensors and the pore water saturation of the concrete was calculated using a weighing test. The results show that the relative humidity inside the dam concrete with a water-binder ratio of 0.5 was kept at 100% in the insulation humidity state; however, the corresponding pore water saturation was not necessarily 100%; the pore water saturation of concrete without fly ash and with 35% fly ash was 85%~89% and 73%~76%, respectively. This indicates that 100% of the pore water saturation of the dam concrete corresponds to 100% of the internal relative humidity, and the internal relative humidity of 100% is not the only relative humidity corresponding to the pore water saturation of 100%. In the insulation humidity state, for concrete with a water-binder ratio of 0.5, the pore water saturation of concrete with 35% fly ash is less than that of concrete without fly ash.
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Key words:
- dam concrete /
- relative humidity /
- pore water saturation /
- fly ash content
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表 1 混凝土配合比
Table 1. Mix proportions of concrete
水胶比 粉煤灰掺量/% 单位体积用量/(kg·m−3) 减水剂 水泥 水 粉煤灰 砂子 石子 0.5 0 1.716 264.0 132 0 761.26 1 477.74 35 1.716 171.6 132 92.4 761.26 1 477.74 
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表 2 大坝混凝土试验方案
Table 2. Test schedule of dam concrete
试件编号 水胶比 粉煤灰掺量 试件尺寸 养护状态 养护龄期/d 试验 1#、2# 0.5 0 150 mm×150 mm×150 mm （20±2）℃绝湿 27 湿度监测30 d 3#、4# 浸水30 d 5#、6# 35% 湿度监测30 d 7#、8# 浸水30 d
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表 3 试验结果
Table 3. Test results
编号 水胶比 粉煤灰掺量/% 养护 第28 d测湿/% 测湿/浸水30 d 初始质量/g 烘干质量/g 含水率/% 平均含水率/% 1# 0.5 0 绝湿养护27 d 100 100% 19.15 17.85 7.28 7.48 2# 0.5 0 100 100% 24.99 23.21 7.67 3# 0.5 0 100 浸水饱和 18.91 17.41 8.62 8.34 4# 0.5 0 100 浸水饱和 38.46 35.59 8.06 5# 0.5 35 100 100% 26.47 24.56 7.78 7.94 6# 0.5 35 100 100% 29.49 27.28 8.10 7# 0.5 35 100 浸水饱和 13.74 12.41 10.72 10.20 8# 0.5 35 100 浸水饱和 23.35 21.29 9.68
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表 4 混凝土孔隙水饱和度与内部相对湿度
Table 4. Concrete pore water saturation and internal relative humidity
单位：% 编号 水胶比 粉煤灰掺量 含水率 孔隙水饱和度 内部相对湿度 1# 0.5 0 7.28 85 100 2# 0.5 0 7.67 89 100 3# 0.5 0 8.62 100 100 4# 0.5 0 8.06 94 100 5# 0.5 35 7.78 73 100 6# 0.5 35 8.10 76 100 7# 0.5 35 10.72 100 100 8# 0.5 35 9.68 90 100
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