膨胀剂对混凝土早期基本徐变的影响
作者:
作者单位:

1.东南大学 材料科学与工程学院,江苏 南京 211189;2.江苏苏博特新材料股份有限公司 高性能土木工程材料国家重点实验室,江苏 南京 211103

作者简介:

李 华(1987—),女,江苏南京人,东南大学博士生,江苏苏博特新材料股份有限公司高级工程师. E-mail: lihua@cnjsjk.cn

通讯作者:

李 华(1987—),女,江苏南京人,东南大学博士生,江苏苏博特新材料股份有限公司高级工程师. E-mail: lihua@cnjsjk.cn

中图分类号:

TU528.01

基金项目:

“十三五”国家重点研发计划项目(2017YFB0310100);国家自然科学基金资助项目(51738004,52008189)


Effect of Expansive Additives on Basic Creep of Early-Age Concrete
Author:
Affiliation:

1.College of Materials Science and Engineering, Southeast University, Nanjing 211189, China;2.State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Sobute New Materials Co., Ltd., Nanjing 211103, China

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    摘要:

    研究了自制CaO和MgO膨胀剂的掺加对C60自密实混凝土力学、变形性能及基本徐变的影响,并将徐变测试结果与fib 2010模型计算结果进行了对比.结果表明:6% CaO膨胀剂、6% (CaO+MgO)膨胀剂和10% (CaO+MgO)膨胀剂的掺加对C60自密实混凝土的抗压强度和弹性模量影响较小,但会显著降低混凝土自收缩,并增大其基本徐变变形;混凝土的徐变度和徐变系数基本随着膨胀剂总掺量或CaO膨胀组分掺量的提高而增大;当CaO膨胀剂掺量较低时,混凝土徐变度实测结果与fib 2010模型计算结果吻合度较好,CaO膨胀剂掺量较高时,混凝土徐变发展趋势明显高于模型计算结果,复合掺加MgO膨胀剂后,随着持荷时间的延长,混凝土徐变进一步增加.对于CaO膨胀剂掺量较高以及复合掺加MgO膨胀剂的混凝土,有必要研究膨胀对徐变随时间发展系数的影响,进而对模型进行修正.

    Abstract:

    The effects of CaO-based and MgO-based expansive additives on the mechanical, deformation properties and basic creep of C60 self-compacting concrete were studied, and the test results of creep were compared with the calculation results of the fib 2010 model. The results show that the incorporation of 6% CaO-based expansive additive and 6%, 10% CaO/MgO composite expansive additives has little effect on the compressive strength and elastic modulus of C60 self-compacting concrete, but significantly reduces the autogenous shrinkage and increases the basic creep. The concrete creep compliance and creep coefficient basically increase with the increase of the total amount of expansive additives and the increase of CaO-based expansive additive. Under the low content of CaO-based expansive additive, the test results of creep compliance of concrete are in good agreement with the calculation results of fib 2010 model, but under the condition of high content of CaO-based expansive additive, the development trend of concrete creep is significantly higher than that of the calculation results. When mixing with MgO, the creep further increases with the increase of load holding duration. For the concrete incorporating high content of CaO-based and MgO-based expansive additive, it is necessary to study the influence of expansion on the development of creep with time, and then to modify the model.

    表 2 混凝土的配合比Table 2 Mix proportion of concrete
    表 3 混凝土徐变测试时的施加荷载值Table 3 Load values at different loading ages for concrete
    图1 混凝土轴心抗压强度Fig.1 Uniaxial compressive strength of concrete
    图2 混凝土弹性模量Fig.2 Elastic modulus of concrete
    图3 混凝土在不同加载龄期的总应变随时间的变化Fig.3 Development of total strain of concrete with time at different loading ages
    图4 混凝土的自生体积变形随时间的变化Fig.4 Development of autogenous deformation of concrete with time
    图5 混凝土徐变系数Fig.5 Creep coefficient of concrete
    图6 混凝土徐变度Fig.6 Creep compliance of concrete
    图7 混凝土徐变度fib 2010模型计算结果与实测结果的对比Fig.7 Comparison between calculated value of creep based on fib 2010 model and measured value of concrete
    表 1 CaO膨胀剂和MgO膨胀剂的化学组成Table 1 Chemical compositions of CaO-based and MgO-based expansive additive
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引用本文

李华,汪洋,王育江,刘加平,田倩.膨胀剂对混凝土早期基本徐变的影响[J].建筑材料学报,2022,25(3):256-262

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  • 收稿日期:2020-12-03
  • 最后修改日期:2021-01-05
  • 在线发布日期: 2022-03-28
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