GROUT COMPOSITE FOR PRESTRESSED CONCRETE PSC BRIDGE HAVING DUAL-EXPANSION EXPANSIVE ADMIXTURE

摘要

Provided is a grout composite for a prestressed concrete (PSC) bridge having a dual expandable expansion material. To compensate shrinkage of grout for a prestressed concrete (PSC) bridge, a dual expandable expansion material is used to cause expansion twice immediately after the grout (plastic state) is injected and after the grout is hardened, thereby suppressing generation of an initial microcrack from occurring, and thus, it is possible to reduce bleeding and latency. In addition, the grout is expanded twice by the dual expandable expansion material such that it is possible to reduce expansion energy of the hardened grout. Accordingly, it is possible to minimize generation of internal micro-bubbles and cracking of the grout material, thereby increasing water tightness. Furthermore, it is possible to maintain a water-cement ratio (W/C) at a high level by using a suitable shrinkage reducing agent and a fluidizing agent such that fluidity and injection workability of the grout can be improved. Moreover, instead of mixing cement with an admixture in a work site as it is conducted in a conventional case, the cement, silica, the dual expandable expansion material, the fluidizing agent, the shrinkage reducing agent, and a thickener for reducing bleeding are prepared as premix type powder, and the premix type powder is mixed with water and used in the work site such that it is possible to easily manage the quality of the grout.