(1) The particle size meets the requirements and the particle grading is continuous;
(2) There is no yellow skin (mud on the surface), mud balls, large mud blocks, and large-grained stones;
(3) The less the content of needle-shaped and flaky particles, the better (the content of needle-shaped and flaky particles in stones used for pumped concrete should not exceed 10%);
(4) The less the shale content, the better (because shale has lower strength and increases the content of flaky particles).
