Perlite is used worldwide in horticulture, construction and for industrial applications. Alternatives for perlite will depend upon application specific uses and characteristics. As a natural form of glass, perlite is inert chemically and has a pH of about 7. The expanded form is lightweight and may weigh as little as two pounds per cubic foot. In addition to these unique characteristics, perlite has insulating and fire-resistant qualities.
Perlite is used in soil-based and soilless growing mixtures to provide aeration and moisture retention. As a sterile, lightweight and weed-free product it is used in commercial and home gardens. Generally, sphagnum peat moss, course sand, vermiculite and perlite are used in varying proportions to create growing mixes. Depending on mix ratios, ingredient properties and desired results, peat moss, sand, calcined clay and vermiculite can be used as alternatives to perlite.
As a mineral ingredient similar to perlite, vermiculite is used in place of perlite. It is lightweight, naturally made expandable clay. Vermiculite retains water, nutrients and air, while perlite does not. However, when compacted, the ability of vermiculite to retain water and air is reduced.
Sphagnum peat moss is added if insufficient water is being retained. Peat moss is also a lightweight, coarse material that offers good aeration and holds water well. However, it is possible that sphagnum peat moss may hold too much water.
Perlite alternatives for aeration purposes are calcined clay and coarse, sharp sand. While perlite is lighter than sand and clay, sand and clay are less expensive and offer good drainage.
Perlite is also used as a carrier for herbicides and fertilisers. Alternatively, fertilisers and herbicides can be applied manually as needed without a carrier.
According to the North Carolina State Energy Office, perlite is no longer used for loose-fill insulation. However, older homes may contain perlite insulation. Other materials used for insulation are fibre glass, rock wool and loose–fill cellulose insulation made from newsprint, cardboard or other waste paper products.
Perlite is used as an aggregate in cement or asphalt or added to paint and exterior coating materials and tiles for texture and fire resistance. Other aggregates that can be used in cement as perlite alternatives are sand and gravel, which can be used as they are mined. Limestone and dolomite must be crushed first, but can be sized to meet project specifications. Other mineral aggregates that are used in cement are shale, shells and slag.
Alternatives for perlite ceilings include using fibreglass, gypsum wallboards or formaldehyde-free rock wool. Rock wool tiles are recyclable and have excellent light reflectance. Fibreglass offers good noise reduction coefficients. Perlite tiles are good for high moisture areas and are considered low for volatile organic compounds.
Industrially, perlite is used as filler for plastics, cement, and for petroleum, water and geothermal wells. Additionally, it is used as a filter media in pharmacological applications, food products, in municipal systems and swimming pools and as an abrasive in soaps and cleaners. Perlite substitutions for fillers and filters include diatomite, expanded clay, shale, slag and vermiculite. Pumice can be substituted for perlite abrasives.
- Perlite.net: Basic Facts About Perlite
- Penn State: Department of Horticulture Fact Sheet: Homemade Potting Media
- Arizona Cooperative Extension: Potting Media for Containers
- North Carolina State Energy Office: Does Your Home Need More Insulation?
- New Mexico Institute Mining and Technology: Geology of Industrial Minerals:2007