Due to the early deterioration of pile cap foundations in residential buildings and bridges in the metropolitan region of Recife, several samples taken from a pile cap block of a residential building, built about ten years ago, were studied. The problem of the extensive cracking in the pile cap foundation had its origin in the delayed ettringite formation, possibly due to a high heat of hydration due to the concreting of the large volume of concrete. In this work, laboratory tests were performed to evaluate the transport properties of concrete samples, as well as their physical and chemical composition using advanced analyses. The tests performed in the experimental campaign were the apparent porosity, gas permeability, scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The presence of crystalline products of the alkali-aggregate reaction was proven through physical–chemical analyses, such as Raman spectroscopy and EDS. Moreover, the ettringite crystals were observed in XRD standards, SEM images and in the chemical composition of EDS. The porosity showed a high value (between 9 and 10%), as well as the concrete permeability (10^–16 m² and 10^–15 m²), determining the negative influence of ISR on the transport properties. Therefore, the methods used have proven to be effective in understanding the problem encountered and have the potential to be used in the design and execution of pile cap blocks.

由于累西腓大都会地区住宅建筑和桥梁中桩帽基础的早期退化，研究了从大约十年前建造的住宅建筑的桩帽中获取的一些样本。桩帽基础广泛开裂的问题起因于钙矾石形成延迟，这可能是由于大量混凝土的凝结产生了很高的水化热。在这项工作中，进行了实验室测试，以使用高级分析方法评估混凝土样品的运输性能以及其物理和化学组成。实验过程中进行的测试是表观孔隙率，气体渗透性，扫描电子显微镜，X射线衍射和拉曼光谱。通过物理化学分析（例如拉曼光谱和EDS）证明了碱聚集反应的结晶产物的存在。此外，在XRD标准品，SEM图像和EDS的化学组成中观察到钙矾石晶体。孔隙率显示出较高的值（介于9％和10％之间）以及混凝土渗透率（10％）。^{– 16}  m ²和10 ^–15  m ²），确定了ISR对运输性能的负面影响。因此，已证明所使用的方法在理解遇到的问题方面是有效的，并且具有在桩帽块的设计和执行中使用的潜力。