Special grouting agent for post-tensioned prestressed concrete beams of highway bridges and culverts and preparation method thereof

The invention discloses a special grouting agent for post-tensioned prestressed concrete beams of highway bridges and culverts and a preparation method thereof. The grouting agent comprises the ingredients of a water reducing agent, a plastic expanding agent, an expanding agent, a flowing deformation assistant, a water-retaining agent, a retarder, a defoamer, a superfine active mineral admixture and the like. Low ratio of water to glue (0.26-0.28), high fluidity (the initial fluidity being equal to or less than 17s), no bleeding (free bleeding rate in 24hours being 0%) and early expanding (free expanding rate in 3hours being 0-2%) of grouting materials are realized after the grouting agent is added, so that quality reliability and durability of post-tensioned prestressed duct grouting areimproved, the problems of non-full and incompact grouting in duct grouting are fundamentally solved and the service life of prestressed concrete structure bridges is prolonged to realize a qualitative leap of the grouting material performance.