CPC E04D 1/20 (2013.01) [C03C 10/00 (2013.01); C04B 33/04 (2013.01); C04B 33/32 (2013.01); C04B 35/10 (2013.01); C04B 35/18 (2013.01); C04B 35/62695 (2013.01); C04B 35/636 (2013.01); C04B 35/64 (2013.01); E04D 1/16 (2013.01); C04B 2235/3217 (2013.01); C04B 2235/349 (2013.01); C04B 2235/528 (2013.01); C04B 2235/5427 (2013.01); C04B 2235/5436 (2013.01); C04B 2235/5463 (2013.01); C04B 2235/5472 (2013.01); C04B 2235/5481 (2013.01); C04B 2235/95 (2013.01); C04B 2235/9646 (2013.01); C04B 2235/9661 (2013.01); E04D 2001/005 (2013.01); Y02A 30/254 (2018.01); Y02B 80/00 (2013.01); Y10T 428/24413 (2015.01); Y10T 428/24421 (2015.01)] | 16 Claims |
1. A plurality of roofing granules, each roofing granule comprising a base particle of material thermally stable up to a first temperature of at least 900 C.; and
coated on the base particle, a coating layer of sintered kaolin, sintered bauxite, or a sintered combination of kaolin and bauxite, the coating layer having a crystalline content of at least 90 percent as determined by x-ray diffraction, wherein the crystalline content is the proportion, on a weight basis, of anhydrous crystalline material.
|