一、砂石吸水与混凝土性能的关系任何干态的砂石,接触水后,都有吸水的本能。我们以往都采用绝干砂石(不含自由水)作为混凝土配合比设计的依据。这样,在试配混凝土时,干砂石与水接触,不断吸收水泥浆中的水分,使设计的水灰比发生改变,因而引起了混凝土强度的波动。另一方面,由于砂石吸水是初期较快,而后减慢,直到饱和为止。这就造成拌制混凝土初期,坍落度值变化大,极易造成测试误差。因此,用绝干砂石做配合比试验不尽理想。但更突出的问题,是施工时砂石达不到绝干要求,一般采取先测出绝干砂石的含水率,而后在计算施工配合比时,扣除多余的水。表面看这样做是合理的,实际在计算过程中,错把砂石已吸收到表层里的水,也计算在原设计总用水量中去了。这就减少了原水 First, the relationship between sand and water absorption and concrete performance Any dry sand, after contact with water, have water instinct. In the past, we used dry sand (free water) as the basis for concrete mix design. In this way, during the trial mix of concrete, the dry sandstone is in contact with water and continuously absorbs the moisture in the cement slurry, which changes the water-cement ratio of the design, thus causing fluctuations in the strength of the concrete. On the other hand, the water absorption of sandstone is faster at the beginning and then slows down until saturation. This results in the initial stage of the mixed concrete, the slump value changes greatly, and it is very easy to cause the test error. Therefore, it is not ideal to use dry sand for the blend ratio test. However, the more prominent problem is that sand and gravel do not meet the requirement of absolute dryness during construction. Generally, the moisture content of dry sandstone is measured first, and then excess water is deducted when the construction mix ratio is calculated. On the surface, it is reasonable to do so. In the calculation process, the water that has been absorbed into the surface by mistake is also calculated in the total water consumption of the original design. This reduces raw water