JTS/T 236-20 19 "Technical Specification for Concrete Testing of Waterway Engineering", in the test procedure, 400g sample is weighed, placed in a container, injected with clear water, which is about 150mm higher than the sample, and soaked for 2 hours after being evenly stirred; Wash the sample, separate the sand, pour the muddy water on the screens of 1.25mm and 80μm (put the larger one on it), and filter out the particles smaller than 80μ m. Before the test, both sides of the screen should be soaked with water to avoid sand loss during the whole test. Inject water into the container again, and repeat this until the water in the container is clear by visual inspection; Dry the particles on the two sieves to constant weight, and then weigh them.