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为了在混凝土生产过程中测出每盘砂的含水率,使配料符台配比的要求,国内外生产与科研中普遍采用下述方法:电阻法、中子法、红外线法、微波法、电容法等。本文着重对目前应用和研究较多的电容法作一分析。电容法测水基本上分二部分:传感器及二次电路。传感器内充满砂,在20℃时水的介电常数(ε_w=80.08)比砂的介电常数(ε_5=3.5～3.2)大得多,故当砂中含水率变化时,电容传感器中的电容量也将相应变化,用电路处理这种变化量便可指示出含水率。
In order to measure the moisture content of each sand in the production process of concrete, and to meet the requirements for the ratio of raw materials to batches, the following methods are commonly used in domestic and foreign production and scientific research: resistance method, neutron method, infrared method, microwave method, and capacitance Law and so on. This article focuses on an analysis of the capacitive methods currently used and studied. Capacitance testing basically consists of two parts: sensor and secondary circuit. The sensor is filled with sand. At 20°C, the dielectric constant of water (ε_w=80.08) is much greater than the dielectric constant of sand (ε_5=3.5 to 3.2). Therefore, when the moisture content in the sand changes, the electrical energy in the capacitive sensor The capacity will also change accordingly, and the use of a circuit to process this change will indicate the moisture content.