Precast concrete usually weights 100 lbs per cubic foot. Gfrc usually weights 10 lbs per lin foot. Precast concrete is a lower end product. Precast concrete does not simulate limestone as does cast stone. Precast concrete resembles finished concrete and the surface looks like your garage floor.
Cast stone resembles limestone or sandstone.
Lightweight cast stone is not a new product but has been used for years, but not in architectural uses. We at Cast Stone Co are pleased to introduce this lightweight cast stone or lightweight precast concrete if you will, into our line of precast concrete and cast stone. Because lightweight cast stone is made from fiberglass mixed with real limestone which gives it that stone look, it is not suitable for fireplace mantle treatments. Although it is A-class fire rated it may scorch. Precast concrete is usually used in lower end track homes where budget is a concern, cast stone is usually used in higher end homes where budget is not a concern.