掺风积沙的PVA-FRCC早期自生收缩性能
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1.内蒙古工业大学土木工程学院;2.中国建筑土木建设有限公司;3.内蒙古工业大学资源与环境工程学院

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内蒙古自治区自然科学(2023LHMS05016);国家自然科学(52468039,51968056);内蒙古自治区科技计划项目(2022YFHH0153)


Early Autogenous Shrinkage Performance of PVA-FRCC Mixed with Aeolian Sand
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1.School of Civil Engineering,Inner Mongolia University of Technology;2.China Construction Civil Engineering Construction Co. Ltd;3.School of College of Resources and Environmental Engineering,Inner Mongolia University of Technology

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    摘要:

    为研究掺风积沙的聚乙烯醇纤维水泥基复合材料(Polyvinyl alcohol fiber cement-based composites,简称PVA-FRCC)早期自生收缩性能并建立自生收缩预测模型,本文以风积沙取代率、纤维体积率、水胶比及砂胶比为研究变量,通过收缩试验测试了材料7d内的自生收缩,总结了各因素对自生收缩的影响规律,并通过低场核磁试验测试了试件内部孔隙流体饱和度、孔隙率与孔径,揭示了风积沙对自生收缩的影响机理。结果表明:风积沙具有多孔吸水性,且弹性模量较小,水胶比较小时自生收缩随风积沙取代率提高而增大,水胶比较大时自生收缩随风积沙取代率提高而减小;PVA纤维的内养护作用降低了自生收缩;水胶比较小时水化反应引起的化学收缩增大,导致自生收缩增加;砂胶比提高使风积沙绝对含量提高,导致自生收缩增大;掺风积沙的PVA-FRCC整体孔径较小,最可几孔径在10 nm左右,风积沙取代率提高后小孔孔隙率提高是自生收缩增大的主要原因。最后考虑各因素影响,建立了掺风积沙的PVA-FRCC早期自生收缩预测模型,模型计算值与试验值吻合良好。

    Abstract:

    In order to study the early autogenous shrinkage performance of polyvinyl alcohol fiber cement-based composites ( PVA-FRCC ) mixed with aeolian sand and establish a autogenous shrinkage prediction model. This paper takes aeolian sand replacement rate, fiber volume rate, water-binder ratio and sand-binder ratio as research variables. The autogenous shrinkage of the material within 7 days was tested by shrinkage test, and the influence of various factors on autogenous shrinkage was summarized. The pore fluid saturation, porosity and pore size of the specimen were tested by low-field nuclear magnetic resonance test. The influence mechanism of aeolian sand on autogenous shrinkage is revealed. The results show that aeolian sand has porous water absorption and small elastic modulus. When the water-binder ratio is small, the autogenous shrinkage increases with the increase of the replacement rate of aeolian sand. When the water-binder ratio is large, the autogenous shrinkage decreases with the increase of the replacement rate of aeolian sand. The internal curing effect of PVA fiber reduces the autogenous shrinkage. When the water-binder ratio is small, the chemical shrinkage caused by the hydration reaction increases, resulting in an increase in autogenous shrinkage ; the increase of sand-binder ratio increases the absolute content of aeolian sand, which leads to the increase of autogenous shrinkage. The overall pore size of PVA-FRCC mixed with aeolian sand is small, and the most probable pore size is about 10 nm. The increase of pore porosity after the increase of aeolian sand replacement rate is the main reason for the increase of autogenous shrinkage. Finally, considering the influence of various factors, the early autogenous shrinkage prediction model of PVA-FRCC mixed with aeolian sand was established. The calculated values of the model were in good agreement with the experimental values.

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  • 收稿日期:2024-12-23
  • 最后修改日期:2025-03-04
  • 录用日期:2025-04-08
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