轻质碳酸钙为什么比重质碳酸钙密度小？ - 知乎 两者块体密度没有多大差别，堆积密度则分别为 0 5-0 7 g cm3 和 0 8-1 3 g cm3，主要差别在于 PCC 颗粒长径比大，是纺锤形，不容易紧密堆积，GCC 长径比小 (更接近球形)，容易实现紧密堆积。
Corgi PCC display track? - O Gauge Railroading On Line Forum Are there any off the shelf tracks made that fit a Corgi PCC car? Distance between rails would need to be 33mm or a hair above 1 25" based on my caliper If I need to make, what rail and ties would you guys recommend, these will just be sitting on a shelf