Cemented sand gravel mud-blocking agent and cemented sand gravel mixture

The invention discloses a cemented sand gravel mud-blocking additive and a cemented sand gravel mixture, and belongs to the technical field of cementing materials. The mud-blocking additive disclosedby the invention takes a quaternary ammonium salt polymer as a main component and can be combined with active sites on the surface of soil in sand gravel to form a hydrophobic protective layer, and meanwhile, the adsorption of the surface of the soil to other additives (such as a water reducing agent and an air entraining agent) is reduced, so that the other additives can fully exert respective effects without being influenced by the soil. Meanwhile, composite organic phosphate is added and can react with clay in water to form a complex, so that the anti-mud effect is achieved, and the influence of the mud content on the polycarboxylate water reducing agent is further reduced. Besides, pentasodium phosphate is used as a soil dispersing agent, polyethylene glycol is used as a soil adsorbent, and ethylenediamine tet