塑性膨胀剂对预应力孔道压浆料体积变形与亚微观结构的影响

Effect of Plastic Expansion Agent on the Volume deformation and Submicroscopic Structure of Pre-stressed Duct Grouting Materials

针对预应力孔道压浆料普遍存在的体积收缩问题,研究了含氮有机化合物作塑性膨胀剂对其塑性及硬化阶段变形行为的影响,并通过孔结构和扫描电镜测试,探讨了塑性膨胀剂的作用机理。结果表明:含氮有机化合物品种和掺量对压浆料的自由膨胀率和强度有很大影响,以亚硝基化合物SP-B作塑性膨胀剂较为适宜,掺量以0.02%～0.06%为佳;SP-B塑性膨胀剂通过在压浆料浆体内部释放氮气,产生了均匀、微细的气泡而引发适度的塑性膨胀,有效补偿了浆体的早期体积收缩,且对硬化浆体亚微观结构和力学性能无显著不利影响;掺SP-B塑性膨胀剂的压浆料浆体的早期膨胀过程分为快速膨胀期、缓慢膨胀期和膨胀稳定期三个阶段,进一步复掺UEA膨胀剂,提高了硬化浆体中后期的体积稳定性。

Aiming at the problem of volume shrinkage generally existing in pre-stressed duct grouting materials, the influence of nitrogen-containing organic compounds as plastic expansion agent on the deformation behavior at plastic and hardening stages was studied. And the mechanism of plastic expansion agent was discussed by pore structure and scanning electron microscopy tests. The results show that the types and dosage of the nitrogen-containing organic compounds have very great effects on the free expansion ratio and strengths of grouting materials, and the nitroso compound of SP-B as plastic expansion agent is more suitable than the others and its appropriate dosage is 0.02% -0.06% ; The SP-B plastic expansion agent can form uniform and fine bubbles by releasing nitrogen in grouting materials paste, which cause moderate plastic expansion to compensate the early volume shrinkage of the paste, and have no significantly harmful effects on the submicroscopic structures and mechanical properties of the paste The early expansion process of the grouting material doped with SP-B plastic expansion agent can be divided into three stages of rapid expansion period, slow expansion period and stable expansion period. Moreover, the incorporation of UEA expansion agent together with SP-B plastic expansion agent improves the volume stability of the hardened paste in the middle and late periods.