Assessing the safety of concrete structures subjected to sulfate attack requires a thorough understanding of concrete deterioration degree and the depth of the deteriorated surface layer. However, the existing techniques either solely consider the depth of concrete deterioration or rely on macroscopic mechanical properties to assess the degree of deterioration of concrete, disregarding the non-uniform distribution pattern where deterioration initiates at the surface and diminishes with depth. To address this limitation, an approach utilizing indentation technology is proposed for determining the degree and depth of concrete deterioration caused by sulfate attack concurrently. Indentation technology, known for its efficacy in characterizing local mechanical properties, such as the elastic modulus of concrete, offers a promising solution. By measuring the variation of elastic modulus along the erosion direction in the deteriorated concrete, valuable insights into the degree and deterioration depth can be gained. This study employed a sulfate attack test on concrete specimens immersed in a 5 % NaSO4 solution, with the proposed method employed to determine the deterioration degree and depth. The results demonstrated that, with increasing exposure time (51, 86, 121, and 180 days), the deterioration depths reached 4.750, 7.425, 11.791, and 14.007 mm, respectively, while the corresponding deterioration degrees at a depth of 2 mm were 6.832 %, 18.806 %, 41.501 %, and 55.116 %. Comparing these findings with existing methods, the proposed method quantitatively characterizes the deterioration depth using micro-indentation technology, overcoming some of the limitations (e.g. immaturity or inapplicability). And, the evolution of the deterioration degree aligns with conclusions presented in published research. Furthermore, the results obtained through the new proposed method offers more accurate insights into the distribution of deterioration degree in concrete structures at various depths. Engineers can identify specific areas of deterioration accurately, targetting maintenance efforts more effectively, leading to improved longevity and durability of concrete structures.

中文翻译：

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硫酸盐侵蚀下混凝土劣化表征的新方法及其应用——利用压痕技术从弹性模量变化中获得见解


评估遭受硫酸盐侵蚀的混凝土结构的安全性需要对混凝土的劣化程度和劣化表层的深度有透彻的了解。然而，现有的技术要么只考虑混凝土劣化的深度，要么依靠宏观机械性能来评估混凝土的劣化程度，而忽略了劣化从表面开始并随着深度而减弱的非均匀分布模式。为了解决这一限制，提出了一种利用压痕技术的方法，用于同时确定硫酸盐侵蚀引起的混凝土劣化的程度和深度。压痕技术以其在表征局部机械性能（例如混凝土的弹性模量）方面的功效而闻名，提供了一种很有前途的解决方案。通过测量劣化混凝土中弹性模量沿侵蚀方向的变化，可以获得对劣化程度和劣化深度的宝贵见解。本研究对浸入 5% NaSO4 溶液中的混凝土样品进行了硫酸盐侵蚀试验，采用所提出的方法来确定劣化程度和深度。结果表明，随着暴露时间的增加（51、86、121 和 180 d），劣化深度分别达到 4.750、7.425、11.791 和 14.007 mm，而在 2 mm 深度的相应劣化程度分别为 6.832 %、18.806 %、41.501 % 和 55.116 %。将这些发现与现有方法进行比较，所提出的方法使用微压痕技术定量表征劣化深度，克服了一些限制（例如不成熟或不适用）。 而且，恶化程度的演变与已发表研究中提出的结论一致。此外，通过新提出的方法获得的结果为不同深度混凝土结构的劣化程度分布提供了更准确的见解。工程师可以准确地识别特定的劣化区域，更有效地进行维护工作，从而提高混凝土结构的使用寿命和耐用性。