Pervious concrete using Steel Slag Aggregate (SSA) is a promising Low Impact Development (LID) and sustainable pavement material solution. This study investigated the enhancing mechanism using SSA instead of limestone in pervious concrete from the perspective of microscopic characterizations. Nanoindentation, Backscatter Electrons - Scanning Electron Microscope (BSE-SEM), and Energy Dispersive Spectroscopy (EDS) tests were conducted to obtain the micro-mechanical, micro-morphological and element composition of the interfacial transition zone (ITZ) and adjacent cement paste. The nanoindentation tests showed that the modulus and hardness of the ITZ in SSA pervious concrete were 44% and 68% higher than those of limestone concrete, and the contour plots showed that ITZ thickness of SSA pervious concrete was around 18 μm, narrower than the 25 μm thickness of limestone samples. The BSE-SEM tests showed that the ITZ of SSA pervious concrete had more hydration products and were more compacted. Specifically, denser flower-shape polyhedral crystals were observed, which was coalesced hydration products including calcium silica hydrates (CSH), calcium hydroxide (CH) and ettringite. The EDS results showed that not only were the contents of silicon and calcium in ITZ of SSA pervious concrete were higher, the silicon and calcium (S/C) ratio of SSA pervious concrete was also 42% higher, indicating that more CSH gel was formed. Based on the change of element composition, the estimated width of the ITZ in SSA pervious concrete was also smaller than that of the limestone sample. In all, the ITZ enhancing mechanism of using SSA includes improved strength, reduced width and densified structure.

使用钢渣骨料（SSA）的透水混凝土是一种很有前途的低冲击发展（LID）和可持续的路面材料解决方案。本研究从微观表征的角度研究了渗透性混凝土中使用SSA代替石灰石的增强机理。进行了纳米压痕，背散射电子-扫描电子显微镜（BSE-SEM）和能量分散光谱（EDS）测试，以获得界面过渡区（ITZ）和相邻水泥浆的微机械，微形态和元素组成。纳米压痕试验表明，SSA透水混凝土的ITZ模量和硬度比石灰石混凝土分别高44％和68％，等高线图表明，SSA透水混凝土的ITZ厚度约为18μm，厚度小于25μm的石灰石样品。BSE-SEM测试表明，SSA透水混凝土的ITZ具有更多的水合产物，并且更致密。具体地，观察到致密的花形多面体晶体，其为包括水合二氧化硅二氧化硅（CSH），氢氧化钙（CH）和钙矾石的聚结水合产物。EDS结果表明，不仅SSA透水混凝土的ITZ中的硅和钙含量更高，而且SSA透水混凝土的硅和钙（S / C）比也提高了42％，表明形成了更多的CSH凝胶。根据元素组成的变化，SSA透水混凝土中ITZ的估算宽度也小于石灰石样品的ITZ宽度。总之，使用SSA的ITZ增强机制包括增强的强度，