Online capacitive detection method for moisture content of aggregate based on edge effect

Abstract

The moisture content of aggregate has an important influence on the final mix proportion of concrete and the quality of finished products. The detection methods of moisture content include offline and online. At present, the offline oven-dried method which is inefficient is often used for measurement. The capacitance method is easy to implement, low cost, high precision, low power consumption and fast response. However, the traditional capacitance measurement method must ensure that the space inside the plate is full of medium, which is more suitable for offline measurement. In order to realize online measurement, a moisture content detection method of aggregate based on edge effect is proposed. The wear of the plate can be avoided effectively by using the coplanar scattering field capacitive plate combined with the striker plate. The signal processing circuit uses a single chip solution PCAP01 to effectively improve the anti-interference ability of the detection circuit. The developed sensor is suitable for inner water detection of aggregate. The experimental results show that the effective measurement range of the sensor is 0 ∼ 1.0%,the penetration depth is 10 mm, the resolution is 0.1%, the hysteresis error is 2.69%, and the repeatability error is 10.31%.