施工扰动对碾压混凝土层间结合质量的影响研究

发布时间：2018-02-25 17:28

本文关键词： RCC 直接铺筑允许时间初凝时间抗剪试验吸水动力法扫描电镜　出处：《浙江大学》2016年硕士论文　论文类型：学位论文

【摘要】：由于碾压混凝土(RCC)分层碾压施工,故其层面出现薄弱环节的几率比常规混凝土要大。已有试验结果表明,随着层面间隔时间(从下层RCC拌合物加水开始,一直到上层RCC浇筑完成所历经的时间)的延长,抗剪断强度逐渐降低。因此,研究RCC层间结合质量的问题显得尤为必要。为模拟施工现场分层碾压铺筑RCC的振动效果,在实验室中,当试件加压振动成型后,每间隔1h对相应砂浆试块(用于初凝时间试验)和RCC试块(用于抗剪试验)无压重扰动一次,扰动持续时间分别为4s、8s、12s(以下简称扰动),并以无扰动(加压振动成型后不做任何处理)砂浆试块和RCC试块做参照。本文首先针对RCC的初凝时间进行了研究。通过设计三种不同的配合比,并改变材料温度、减水剂掺量和扰动条件,从RCC胶凝材料微观机理的角度,对RCC的凝结时间试验结果进行了分析。结果表明,浇筑时的材料温度对初凝时间的影响较小。含缓凝成分的减水剂掺量对RCC初凝时间的延长作用显著。扰动(每间隔1h对相应砂浆试块无压重扰动一次,扰动持续时间分别为4s、8s、12s)对RCC初凝时间有显著的延长作用。扰动的持续时间越长,初凝时间延后越多,但延后的值不大。若以RCC层间抗剪强度不低于本体(下层混凝土铺筑完成后立即铺筑上层混凝土的RCC)抗剪强度的85%为控制标准来推求RCC直接铺筑允许的层间间隔时间(以下简称直接铺筑允许时间),试验结果表明,无扰动与受扰动情况下的直接铺筑允许时间有较大差异,而不同扰动持续时间(每间隔1h对相应RCC试块无压重扰动一次,扰动持续时间分别为4s、8s、12s)的RCC之间的直接铺筑允许时间差异较小；直接铺筑允许时间控制值随着扰动持续时间的增加而有所增加。吸水动力法实验结果表明,施工扰动、层间间隔时间延长会使RCC重量吸水率增加,使其平均孔径增加,扫描电镜实验结果佐证了吸水动力法的实验结果。
[Abstract]:Because of the layered roller compaction construction of RCC, the probability of weak link in the layer of RCC is higher than that in the conventional concrete. The experimental results show that with the interval between the layers (starting with adding water to the lower layer of RCC mixture), The shearing strength decreases gradually with the prolongation of the time to the completion of RCC pouring in the upper layer. Therefore, it is necessary to study the quality of interlayer bonding of RCC. In order to simulate the vibration effect of layered compaction RCC in construction site, In the laboratory, the corresponding mortar samples (for initial setting time test) and RCC test blocks (for shear tests) have no pressure and weight disturbance once every 1 hour after the specimen is formed by pressurized vibration. The duration of the disturbance is 4 sg / 8 sL / 12s (hereinafter referred to as disturbance), and compared with the undisturbed mortar sample and RCC sample. The initial setting time of RCC is studied in this paper, and the results are as follows: (1) in this paper, the initial setting time of RCC is studied. For three different proportions, At the same time, the setting time test results of RCC cementitious materials are analyzed from the point of view of the microscopic mechanism of RCC cementitious materials by changing the material temperature, water reducer content and disturbance conditions. The results show that, The material temperature has little effect on the initial setting time. The content of water reducer with retarding component has a significant effect on prolonging the initial setting time of RCC. The duration of disturbance was 4sm ~ 8sm ~ (12 s). The longer the duration of disturbance was, the longer the initial setting time was, and the longer the initial setting time was, the longer the initial setting time was, and the longer the disturbance duration was, the longer the initial setting time was. If the shear strength of the RCC layer is not lower than that of the main body (RCCs of the upper layer concrete immediately after the completion of the lower concrete paving) as the control standard, the allowable interval between the layers of the RCC can be obtained by means of the control standard. Time (hereinafter referred to as the allowable time for direct paving), the test results show that, The allowable time of direct paving under the condition of no disturbance and disturbance is quite different, and the duration of different disturbance (one time per 1 hour interval to the corresponding RCC sample without pressure-weight disturbance), The difference of allowable time of direct paving between RCC with disturbance duration of 4 s-1 / 8 s-1 / 12s is small, and the control value of direct paving allowable time increases with the increase of disturbance duration. The experimental results of hydrodynamic method show that the construction disturbance is disturbed. The increase of interlaminar interval will increase the weight water absorption rate of RCC and increase its average pore size. The results of SEM experiments confirm the experimental results of hydrodynamic method.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TV544.921

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