The specific surface area of soil grains (SSA) influences the physical and chemical properties of soil. Despite the widespread application of the SSA, it is often determined by analytical equations or estimated using empirical relationships and visual comparisons. On the other hand, little attention has been paid, especially to three-dimensional and precise measurements. In this study, the precise SSA and shape coefficient was measured in a group of aggregate with different sizes and shapes using a novel method. Geometrical properties such as volume and surface area were measured for each particle using X-ray micro-computed tomography (µCT) images and image processing. The particle shape coefficient was obtained from the specific surface area and effective diameter. Further, the particle shapes were measured in three distinct characteristics, sphericity, roundness, and roughness. Particle's roundness was measured by Wadell’s formula in the plan outline, which did not show an agreement with the shape coefficient. Nevertheless, as the particle sphericity decreases and roughness increases, the shape coefficient is increased. Hence, the shape coefficient of grains was classified based on the sphericity and the surface roughness. The measured SSA and shape coefficient, for 12 gradations with the three different particle size distribution and four different particle shapes, indicated good agreement with predictive analytical relations for rounded and crushed grains and more dissimilarity for flaky and elongated grains. This novel method can provide the quantitative/qualitative classification for non-spherical particles and also improve our understanding on the properties of granular media.

土壤颗粒的比表面积（SSA）影响土壤的物理和化学性质。尽管SSA的广泛应用，但它通常是由解析方程确定的，或者是通过经验关系和视觉比较来估算的。另一方面，很少关注，尤其是三维和精确的测量。在这项研究中，使用一种新方法对一组具有不同尺寸和形状的骨料测量了精确的SSA和形状系数。使用X射线微计算机断层扫描（µCT）图像和图像处理，测量了每个粒子的几何特性，例如体积和表面积。由比表面积和有效直径获得颗粒形状系数。此外，还通过三个不同的特性对颗粒形状进行了测量：球形度，圆度和粗糙度。粒子的圆度是通过平面轮廓中的Wadell公式测量的，该公式与形状系数不一致。然而，随着颗粒球形度的降低和粗糙度的增加，形状系数增加。因此，基于球形度和表面粗糙度对晶粒的形状系数进行分类。对于三个具有不同粒度分布和四个不同颗粒形状的12个渐变，所测得的SSA和形状系数表明，与圆形和压碎晶粒的预测分析关系相符，而对于片状和细长晶粒的相异性更高。