纳米粘土改性自密实混凝土的免振滑模施工效果研究

Study on construction effect of vibration-free slip-form for modified self-compacting concrete mixed with Nano-clay

为解决滑模施工过程中混凝土过振引发的骨料沉降离析及含气量降低等问题,采用一种自制实验室装置用于模拟水平表面免振滑模施工,并确定了其操作参数。通过掺加纳米粘土,对自密实混凝土进行改进并应用于滑模施工,且确定了适于免振滑模施工的新拌混凝土工作性能范围。研究了纳米粘土对混凝土免振滑模施工效果的影响,选取了边缘坍落度和表面平整度两个参数对施工效果进行评价。结果表明,滑模装置移动速度宜控制在0.25 m/min左右,混凝土填充量为模具箱体竖向高度的60%~80%,滑模配重为28.6 kg左右。掺加纳米粘土的新拌混凝土坍落度应该控制在210~250mm之间,扩展度在350~420 mm之间。纳米粘土材料掺量为1.0%~1.5%时,可实现混凝土的免振滑模成型。

In order to solve the problem from the settlement and segregation of aggregate as well as the reduction of air content in concrete caused by the over-vibration of concrete during slip-form construction,A self-developed laboratory equipment is adopted for simulating the vibration-free slip-form construction of horizontal surface,and then its operation parameters are determined as well.Through adding Nano clay,the self-compacting concrete is modified and then applied to the slip-form construction,moreover,the range of the workability of fresh suitable for the vibration-free slop-form construction is also determined.Furthermore,the influence from the Nano-clay on the effect of the vibration-free slip-form construction of concrete is studied,thus two parameters,i.e.the edge slump and the surface smoothness,are put forward for evaluating the construction effect.The result shows that the moving speed of the slip-form is better to be controlled to about 0.25 mm/min with the concrete filling volume of 60% ~ 80% of the vertical height of the moulding-box and the slip-form balancing weight of about 28.6 kg.For the new concrete mixed with Nano-clay,the slump must be controlled between 210 ~ 250 mm with the extension between 350 ~420 mm.When the mixing content of Nano-clay material is 1.0% ~ 1.5%,the vibration-free slip-form forming of concrete can be realized.