CECI2预应力筋的防锈保护.pptVIP

In a grout with high w/c ratio the cement particles will set and the water will float on top of the grout (bleed) 在水灰比较高的浆液中，水泥颗粒会硬化，水在浆体表层流动（泌水） A low water-cement ratio stable grout has a constant density over the height of a grout column 水灰比低的稳定的浆体在所灌的柱状体中从上到下密度是恒定的 A stable grout with negligible sedimentation and bleed has negligible volume change 稳定的浆体发生的沉淀与泌水可忽略不计，体积变化也就可忽略不计了 Grout shrinkage does not lead to voids, i.e. does not need to be compensated by expansive admixtures浆体收缩不会导致孔隙的产生，不需要由膨胀剂来补偿 Stability of flow time of grout must be sufficiently long and assured at the expected temperature range浆体流动时间的稳定性在一定的温度范围内必须足够长久并有确定性。 Mud balance to measure density of fluid grout 用以测量浆液密度的泥浆平衡试验 Special grout ? 2000 kg/m3 特殊浆液? 2000 kg/m3 3. Multi-layer protection strategy – fib Bulletin 33 多层保护策略- fib Bulletin 33 It has been recognized that any single layer of protection may be compromised on site. Hence, the concept of multi-layer protection to provide reliable and long-term protection of post-tensioning tendons (TR 47) 公认的是任何一层保护层都可能在工地上被牺牲掉。因此，多层保护的理念是为了给后张预应力筋提供可靠的长期的保护(TR 47) Layers of protection must be adapted to environment, exposure conditions, design concept and detailing of structure, level of anticipated maintenance and inspection, design life, etc. 保护层必须根据环境、暴露情况、设计理念以及结构细节、预期的维修检测水平、设计寿命等进行调整 ? Propose several levels of protection adapted to particular structure and exposure conditions ! 为特定的结构及暴露情况设定几个层次的保护 3. Multi-layer protection strategy 多层保护策略 Scenarios of deterioration/ 衰变情景: Where does water get on and how off structure? 水从结构的哪个部位今日，如何排出？ 3. Multi-layer protection strategy 多层保护策略 Durability factors/ 耐久性因素 : Multi-layer protection (provide redundancy) 多层保护（提供超出必要的保护） Concrete quality and cover (permeability) 混凝土质量及保护层（渗透性） Water-proofing / surface protection 防水/ 表面保护 Drainage system 排水系统 Expansion joints 伸缩缝 Cracking 裂缝 Construction joints 施工缝 Se