Produced from high quality natural ores at 8 facilities in North America, Carmeuse’s milled limestone products are used in a variety of industrial applications offering affordable and versatile solutions including the production of roofing shingles.
Today roofing shingles are made with a limestone-filled, asphalt coating that contains between 50 - 70% filler by weight. Reducing the amount of asphalt, and thereby lowering cost, is the primary motivation for the use of limestone in roofing shingles. Shingle durability and flame retardancy are additional benefits.
Some shingle producers choose to purchase limestone to mill into filler themselves; the majority purchase milled limestone direct from a limestone supplier.
For milled limestone the typical product requirements are:
|1.||CaCO3 content||min. 90%|
|3.||Size||min. 80% passing 20 mesh|
Consistency of filler chemistry, gradation, and moisture are also critical requirements needed to manufacture quality shingles.
Below is a diagram of a typical roofing shingle manufacturing process
Image courtesy of Owens Corning
Benefits of Milled Limestone in Roofing Shingles:
- Lowers cost
- Flame retardancy