| As the important component of elevated highway bridges, prestressed concrete bean direct determine the entire project sawhingz. And being the key material of prestressed concrete bean, grouting agent is able to protect prestressed reinforcement from corrosion, while supply excellent cohesive force between reinforcement and concrete structure. Simultaneously it ensures the effective transfer of prestress, which debase the fatigue failure caused by repeated load. This function of grouting agent improves the reliability and durability. Thus the grouting agent's quality becomes the most important factor for prestressed concrete structure.This paper preparation a new kind of grouting agent by the method of orthogonal experiment design, which resolve some defect existed at the present stage. The summaries show that:(1) As a necessary admixture to grouting agent, superplasticizer is able to visibility promote flow property. Polycarboxylates retains the best water-reducing impact, but it is highly susceptive to aqueous phase, and expensive. Melamines possesses of moderate water-reducing impact, little bleeding and low cost, which is worth extending.(2) During three factors(water-binder ratio, fly ash content, plasticizer content) of grouting agent's flow property and intensity, water-binder ratio is the most salient. The bigger water-binder ratio and plasticizer content, the better flow property. But 0.33 water-binder ratio make grouting agent bleeding, which debase 30min flow property. The form effect of fly ash avails flow property and 7d intensity and yet its infirmness pozzolanic effect is disadvantageous to 28d intensity. Thus 0.32 water-binder ratio,15% fly ash content and 0.5% plasticizer content is the best mix proportion for flow property and intensity.(3) Expansion agent can make the hardened grouting agent expanded. While expansion agent debases the flow property, especially 30min flow property. The experiments'result show that 0.15% retarder (tartaric acid) content is able to solve this problem.(4) The conclusions of durability and mercury penetration test data argue that expansion agent optimizes pore structure when slightly affect porosity. This process makes the grouting agent more compact, and distinct electric flux, frost resistance and volume stability. |
