目前混凝土化学腐蚀损伤程度的检测主要是扫描电镜、 能谱、 XRD衍射等方法, 这些方法对于在役的混凝土结构来说, 易造成破坏, 检测时间长, 连续性差。 提出了一种基于高光谱的混凝土腐蚀产物无损检测新方法。 高光谱检测具有非接触、 方便快捷、 连续无损的优点, 但是受腐蚀混凝土实测光谱的解混模型和分析方法是实际应用的难点。 该研究根据混凝土遭受硫酸钠侵蚀生成产物的特点, 将硫酸钠侵蚀后混凝土的光谱划分成两个组分光谱的线性混合, 一个组分是水泥的水化产物光谱反射率, 另一个组分是硫酸钠侵蚀下生成主要产物钙矾石和石膏的光谱反射率。 在光谱比值导数模型的基础上, 建立混凝土腐蚀产物的光谱解混模型。 以在清水和10%Na₂SO₄溶液中连续浸泡的混凝土试块为研究对象, 按照15 d的采集周期, 在30~120 d连续测量两组混凝土的反射光谱。 数据经过平滑、 包络线去除后, 利用混凝土腐蚀产物的光谱解混模型进行处理。 数据一次解混后, 分析解混后光谱曲线光谱特征和变化规律, 与钙矾石和石膏混合物的标准光谱曲线进行SFF匹配拟合分析。 并结合扫描电镜和X射线衍射方法检测此次试验中钙矾石和石膏腐蚀产物的生成情况。 利用混凝土比值后的光谱曲线除以石膏光谱曲线, 完成了实测光谱的二次解混处理, 分析了钙矾石的生成量在30~120 d腐蚀过程中变化趋势。 试验结果表明, (1)试验中清水和10%Na₂SO₄溶液中不同龄期的两组混凝土, 反射光谱特征随着腐蚀时间的增加区分度明显。 两组试块均在1 445和1 945 nm附近有较强吸收特征, 但吸收深度不同, 10%Na₂SO₄溶液混凝土光谱曲线的吸收深度、 吸收面积明显大于清水中的混凝土; (2)实测光谱曲线经过混凝土光谱解混模型一次处理后的曲线, 在1 450和1 945 nm左右处有明显的吸收深谷, 与石膏和钙矾石混合物标准光谱的光谱特征一致, 两者光谱曲线的SFF匹配拟合数值达到了0.96; (3)利用比值后的光谱除以石膏光谱后的曲线很好的突出了腐蚀产物钙矾石的光谱特征。 发现随着腐蚀龄期的增长, 钙矾石在30~120 d生成量的丰度呈现先降后升趋势。 (4)根据混凝土试块腐蚀状态下的高光谱数据分析、 扫描电镜和X射线衍射的检测结果, 验证了混凝土光谱解混模型在混凝土检测中能够正确解算出腐蚀产物的类型和丰度, 为混凝土高光谱无损检测提供了理论基础。

The current testing of concrete chemical etching mainly includes scanning electron microscope, energy spectrum, X-ray diffraction,which has many disadvantages for the concrete in service such as easy to damage, longertest time, poorer continuity. It was proposed that a novel non-destructive testing of concrete corrosion products based on hyper-spectral technology could be used to overcome this shortage. Hyper-spectral test of concrete has many merits such as non-contact, convenient, and continuous lossless, but there are problems in practical application for the unmixed process and analysis of concrete measured spectrum. It was assumed that the spectrum of the concrete under sodium sulfate was a linear mixture of the two component spectra: one component was the spectral reflectivity of the cement hydration product, and another component was the spectral reflectivity of gypsum and ettringite, according toits features of hydration product in concrete, which was proposed the spectral unmixing model of corrosion products of concrete based on the derivative model of the ratio spectroscopy. The hyper-spectral test of concrete was carried out, and the test objects were two concrete sample groups, which were soaked in water and 10%Na₂SO₄ solution and measured the reflection spectrume very 15 days for 30 to 120 day age of concrete. Themeasured data was smoothed and continuum removed, and then was processedby spectral unmixing model of the corrosion product of the concrete in order to know the features of unmixingspectrum, which was fitted with the standard spectral curve of the mixture of gypsum and ettringite by SFF matching, and observed ettringite and gypsumcorrosion products by SEMand X-ray diffraction in theconcretesamples. the secondary unmixing of the measured spectrum was used the ratio spectrum curve of concrete divided by the gypsumto study ettringiteformation during the 30 to 120 dayscorrosion processing.The result shows that: (1) With the increase of corrosion time, there is obvious difference in the reflectance spectrum curve of two concrete sample groups at different ages in clean water and 10% Na2SO4 solution. Both of them have strong absorption near 1 445 and 1 945 nm, but the absorption depth and absorption area of the spectral curve of 10% Na₂SO₄ solution concrete are significantly larger than that of clear water. (2) After the once-processed about concrete spectral unmixing model, there are clear absorption valley at around 1 450 and 1 945 nm in the ratio spectrum curve, which is consistent with the standard spectrum of the mixture of gypsum and ettringite, and matching fitting value of the SFF reached 0.96; (3) The spectral characteristics of the corrosion product ettringite are well highlighted by the curve after the ratio spectrum divided by the gypsum, which indicate that the abundance of ettringite produced show down first and then upfor 30 to 120 day age of concrete.(4) The results ofhyper-spectral, SEM, and X-ray diffraction ofconcrete corrosion product undersodium sulfate attackare identical, which indicates that the type and abundance of corrosion products of the concrete can be calculated correctly with the spectral unmixing modelin the non-destructive test, and provides a theoretical basis for the research of hyper-spectral nondestructive testing of concrete.