Study on the Gradation of Crushed Sand by Using a Novel Digital Image Processing Methodology

It is a trend to replace the increasing shortage of natural sand with crushed sand for the development of building materials. To meet the construction requirements, it is necessary to measure the shape and gradation of crushed sand that is difficult to control. To solve this problem, a novel digital image processing methodology is proposed in this paper. Through the setting of camera resolution, lens and light source selection, the hardware platform of the measurement system was developed. The shape and gradation characterization method of dynamic falling crushed sand was studied, and the measurement software system was developed. Comparative experimental study of equivalent particle size, study of gradations repeatability experiment, comparative experimental study of dynamic digital image methodology and vibration sieving method of gradations and comparative experimental study before and after correction were conducted, respectively. The experimental results show that the equivalent elliptic Feret short diameter is suitable as the equivalent particle size. The maximum repeatability error appears in the size interval of 1.18–2.36 mm, which is 0.9%. The maximum gradation error is reduced from 6.93% before correction to 2.77% after correction. The maximum error of fineness modulus is reduced from − 0.13 to − 0.01. The accuracy of the developed measurement system can meet the actual engineering requirements, and it can realize the quality monitoring of crushed sand.