自密实PVA-ECC早期开裂性能试验研究

Experimental study on the early cracking performance of self-compacting PVA fiber reinforced cement matrix composites

为研究纤维体积掺量对自密实聚乙烯醇纤维增强水泥基复合材料(自密实PVA-ECC)早期抗裂性能的影响,基于分形理论分析了自密实PVA-ECC表面裂缝的分布特性,提出了约束状态下裂缝扩展模型。结果表明:掺入纤维使得自密实PVA-ECC试件表面裂缝更少、短、细,可有效抑制其表面早期裂缝的产生和扩展;掺0.1%纤维试件表面最大裂缝宽度及总开裂面积较未掺纤维试件分别降低28.41%、28.61%,纤维掺量增至0.4%时,试件表面无可见裂缝;自密实PVA-ECC试件表面早期裂缝分布具有分形特征;所提出的裂缝扩展模型能很好地预测自密实PVA-ECC早期收缩开裂规律,计算误差不超过6%。

To investigate the effect of the fiber volume content on the early cracking-resistance of self-compacting PVA-ECC.Based on the fractal theory, the distribution of the cracks on the surface of self-compacting PVA-ECC specimens were analyzed.A crack propagation model was put forward to predict its early shrinkage cracking behaviors under the constrain condition.The results show that the incorporation of fibers makes the crack less, shorter, and thinner,therefore the generation and expansion of self-compacting PVA-ECC cracks suppressed effectively.Compared to the benchmark specimens, the maximum crack width and total cracking area of the specimens with a fiber content of 0.1% were decreased by 28.41% and 28.61% respectively.No visible cracks were observed on the surface of the specimens with 0.4% fiber addition.It is found that the characteristics of early cracks of self-compacting PVA-ECC obeys to fractal distribution.The crack extending model can well predict the law of early shrinkage cracking, and the calculation error of maximum crack width is less than 6%.