Full-density concrete (usual density 2.35 g/cm3), either poured or in blocks, is the material of choice, although others including sand have been used.
谷歌给的翻译是：全密度混凝土（通常密度2.35 g / cm3），无论是浇筑还是块状，都是选择的材料，尽管其他材料包括沙子已被使用。
怎么看着这么别扭，读不通啊。