在漫湾水电站锚索现场开挖试验中发现其自由段砂浆包裹体存在20 a未凝夹层。采用X射线衍射、电镜扫描和埋置密闭水化试验等手段,从物质成分、微观结构和养护条件等方面,对"未凝夹层"现象的成因做初步的分析和讨论,并得到如下有益的结论:(1)漫湾电厂锚索现场开挖试验20 a未凝夹层表现为:上下坚硬、中间软弱,软弱层厚约1-2 cm,在砂浆包裹体中部呈线状延伸,该夹层水泥浆体20 a未凝、强度极低,将该现象称之为"夹层未凝"现象;(2)X射线、电镜扫描结果发现,未凝夹层中硅酸三钙20 a后仍以熟料形式大量存在,从而证明"夹层未凝"现象的产生与水泥水化反应滞缓有关;(3)埋置密闭水化试验和X射线衍射试验结果进一步排除单纯空气隔绝条件和水泥中掺入黏土产生"夹层未凝"现象的可能。
A phenomenon of grout interlayer without solidification was founded in the in-situ anchor excavation experiment at Manwan hydropower. Three test methods were applied to resolve the problem,which were XRD,SEM and embedded closed hydration tests. Through analyzing the results of tests,some conclusions are achieved. The anchorage grout with the unsolidified interlayer shows just like a sandwich,which is composed of three parts. The up and down parts are hardwares,and the central part is a soft interlayer about 1–2 cm thick. The interlayer is linear extended in the mortar inclusions from the beginning to the end. Many tricalcium silicates are founded in the grout interlayer by XRD and SEM tests. The results indicate that the unsolidified phenomenon is closed to early stage of the cement hydration reaction process. It is proven by the indoor airtight hydration test and XRD results that just embedded closed condition and containing clay in cement can not lead to unsolidified phenomenon.