早龄期混凝土内部湿度发展特征

早龄期混凝土内水分含量是监控混凝土结构开裂的重要参数之一。该文采用数字式温湿度传感器,研究了早龄期普通与高强混凝土内部湿度随浇筑龄期的发展规律。实验结果表明,随浇筑龄期的增长,混凝土内湿度逐渐降低。湿度随龄期的发展规律可描述为早期的水汽饱和期(阶段I,相对湿度100%)及随后的湿度逐渐减小期(阶段II,相对湿度<100%)。阶段I的长短及阶段II中湿度降低的幅度与混凝土水灰比及所在位置有关。早龄期混凝土内水分含量沿高度分布不均,存在明显的湿度梯度。

Development of internal humidity in concrete at early ages

The changes in the internal relative humidity of a concrete slab at early age were measured using a combined digital temperature and humidity sensor. The experimental results show that the internal relative humidity decreased as the concrete aged. The relative humidity inside the concrete first has a saturated vapor stage with 100% relative humidity (stage I) followed by stage during which the relative humidity gradually descreases (stage II). The length of stage I and the magnitude of the relative humidity in stage II are greatly influenced by the initial water content in the concrete, the water/cement ratio, and the measurement location in the concrete. A humidity gradient exists along the concrete specimen at early age.