基于NSGM(1,N)模型的RTSF/PVA矿渣混凝土高温后力学性能分析及预测
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陈东林(1996—),男,硕士研究生。主要从事纤维混凝土结构分析研究。E-mail:aaacan1218@163.com

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TU528.572

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辽宁省教育厅基金项目(JJL201915402);中国电建集团西北勘测设计研究院工程实验监测院项目(SYY-KJ2020-02)资助


Analysis and Prediction of Mechanical Properties of RTSF/PVA Slag Concrete after High Temperature Based on NSGM (1, N) Model
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    摘要:

    为改善混凝土高温后的力学性能,以 RTSF 和 PVA 体积掺量以及矿渣替代率为变量,设置四因素三水平的正交试验,测试 RTSF/PVA 矿渣混凝土在 200 ℃、400 ℃、600 ℃以及 800 ℃后的残余抗压强度;结合电镜扫描分析高温后 RTSF/PVA 矿渣混凝土的微观结构;并采用一种新结构的多变量灰色模型对 RTSF‐PVA/矿渣混凝土进行高温后的强度预测。结果表明:RTSF‐PVA/矿渣混凝土对裂缝的把控能力明显优于素混凝土,600~800 ℃后的最大裂缝宽度仅为素混凝土的 1/3~1/4,但裂纹分布较广;RTSF‐PVA/矿渣混凝土的残余抗压强度随温度升高, 总体上呈降低趋势,当掺量组合为 RTSF 掺量 0.6%、PVA 掺量 0.05% 以及 GBFS 替代率 25% 时,800 ℃后的抗压强度残余率为 56.64%,较素混凝土提高了 14.44%;通过电镜扫描观测到 RTSF‐PVA/矿渣混凝土基体结构更加致密,混凝土劣化主要是因为胶凝物质的分解和骨料膨胀,导致 ITZ 出现缺陷,以及纤维与基体粘结力降低,两者共同作用导致强度降低;建立 NSGM(1,4)模型对 RTSF‐PVA/矿渣混凝土进行高温后的强度预测,平均相对误差控制在 6.3% 以内,模型精度达到Ⅱ级,根据发展系数判断模型可以对 RTSF‐PVA/矿渣混凝土进行高温后强度的长期预测。

    Abstract:

    To improve the mechanical properties of concrete at high temperatures, orthogonal tests with four factors and three levels were set to investigate the residual compressive strength of RTSF/ PVA slag concrete at the temperatures of 200 ℃,400 ℃,600 ℃ and 800 ℃, with the volume fraction of RTSF and PVA and slag replacement rate as variables. At the same time, the microstructure of RTSF/PVA slag concrete after high temperature exposure was analyzed using a scanning electron microscope. A new structure multivariable grey model is used to predict the strength of RTSF-PVA/ slag concrete at high temperatures. The results show that RTF-PVA/slag concrete has better crack control ability than plain concrete, and the maximum crack width at temperatures ranging from 600 ℃ to 800 ℃ is only 1/3~1/4 of that found in plain concrete, but the crack distribution is wider. The residual compressive strength of RTSF-PVA/ slag concrete decreases as the temperature increases. When the mixture of RTSF 0.6%, PVA 0.05% and GBFS 25%, the residual compressive strength of RTSF-PVA/ slag concrete is 56.64% after 800 ℃ exposure, which is 14.44% higher than plain concrete. Scanning electron microscope revealed that the matrix structure of RTSF-PVA/slag concrete is denser. The concrete deterioration is mainly due to the decomposition of cementitious substances and aggregate expansion, resulting in defects in ITZ, and the reduction of the adhesion between fiber and matrix, resulting in the reduction of strength. The NSGM (1,4) model was established to predict the strength of RTSF-PVA/slag concrete after high temperature exposure. The average relative error was controlled within 6.3%, and the accuracy of the model reached level ⅱ . The long-term strength prediction of RTSF-PVA /slag concrete after high temperature could be carried out according to the development coefficient judgment model.

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陈东林,王学志,王晨晨,贺晶晶.基于NSGM(1,N)模型的RTSF/PVA矿渣混凝土高温后力学性能分析及预测[J].防灾减灾工程学报,2023,43(6):1346-1357

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  • 收稿日期:2022-04-04
  • 最后修改日期:2022-06-13
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  • 在线发布日期:2024-01-11
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