How to distinguish the quality of cement brick

Look at the appearance first, then listen to the sound. Now many cement bricks have a crisp feeling from the appearance, and the sound is relatively heavy. Then, open the brick and look inside. Inferior bricks have poor compactness. The knocking sound is crisp and the quality is good. The surface looks smooth and flat, and the structural strength depends on whether you will fall apart after you fall short. If the granular structure is not flattened, mixed evenly, compacted or the cement ratio is small, the best brick is the red brick burned by soil in the past.