高吸水性树脂与纤维对自燃煤矸石混凝土干燥收缩的影响

Effect of super absorbent polymers and fiber on drying shrinkage of spontaneous combustion coal gangue concrete

  • 摘要: 为了探究有效降低自燃煤矸石混凝土收缩的方法,以高吸水性树脂(Super Absorbent Polymers,SAP)和聚丙烯(Polypropylene,PP)纤维掺量为变量,设计了7组自燃煤矸石混凝土试件,开展了自燃煤矸石混凝土干燥收缩试验和基体内部湿度测试试验。探究了SAP与PP纤维对基体收缩性能的影响规律,揭示了基体干燥收缩应变与内部相对湿度之间的变化规律,建立了自燃煤矸石混凝土收缩预测模型。结果表明:SAP和PP纤维的加入均能显著降低自燃煤矸石混凝土的干燥收缩,随着SAP掺量的增加,基体收缩应变先减小后增大;随着PP纤维掺量的增加,基体收缩应变逐渐减小。90d龄期时,SAP掺量为0.2%时对自燃煤矸石混凝土的减缩效果最好,与基准混凝土相比,其试件收缩应变降低了31.3%。SAP与PP纤维的加入可以抑制基体内部湿度的衰减,基体收缩应变与内部相对湿度呈线性变化;通过引入自燃煤矸石骨料影响系数对法国建筑行业规范AFREM中提出的收缩预测模型进行了修正,修正后模型的预测结果与试验结果吻合度较高,可用于自燃煤矸石骨料混凝土干燥收缩的计算。

     

    Abstract: In order to explore the effective method of reducing the shrinkage of spontaneous combustion coal gangue concrete, seven groups of samples were designed with the different dosage of super absorbent polymers (SAP)and polypropylene (PP)fibers, the drying shrinkage test and the internal humidity test were carried out. The effect of SAP and PP fibers on shrinkage performance of spontaneous combustion coal gangue concrete was investigated, the influence of SAP and PP fibers on the internal humidity of the matrix was analyzed, and the law of change between the drying shrinkage strain and the internal relative humidity of the matrix was revealed. The shrinkage prediction model of spontaneous combustion coal gangue concrete was proposed. The results show that the addition of SAP and PP fibers can significantly reduce the drying shrinkage of spontaneous combustion coal gangue concrete. The shrinkage value of the matrix first decreases and then increases with the increasing of the SAP addition; the shrinkage value of the matrix gradually decreases with the increment of PP fibers dosage. At the age of 90 days, when the volume content of SAP is 0.2%, the shrinkage reduction effect of matrix is the best, and the shrinkage strain of the sample is reduced by 31.3% compared with the plain concrete. The addition of SAP and PP fibers can inhibit the decay of the internal humidity; the shrinkage strain and the internal relative humidity of the matrix vary linearly. By introducing the influence coefficient of spontaneous combustion coal gangue aggregate, the AFREM shrinkage prediction model is modified, the predicted results are in good agreement with the experimental results, and the modified shrinkage model can be used for the calculation of dry shrinkage of spontaneous combustion coal gangue aggregate concrete.

     

/

返回文章
返回