Non-hazardous and non-dangerous spent sand has
traditionally been used as "clean fill" in many parts of
Washington State. However, "clean fill" opportunities
have declined in recent years, making exploration and
implementation of other applications essential. Spent
foundry sand has been successfully used throughout the
United States in various applications. Below are some
recycling options for spent sand:
· Asphalt Concrete: Substitution of up to 15% spent
sand for conventional asphalt concrete fine aggregate.
· Compost Additive: Bulking agent for composted yard
waste, to produce topsoil or topsoil additive.
· Concrete: Substitution for regular sand in structural
grade concrete, at low percentages.
· Bricks and Pavers: Encapsulation in a proprietary,
high pressure, pozzolanic process that can encapsulate
and chemically bind various waste materials in C-grade
flyash (a fine particulate ash produced by coal-burning
electrical power plants). The ambient-temperature
process results in bricks that are cost effective and can
be shaped to meet end-user requirements
· Portland Cement: Cement kiln feed for portland
cement. A study by the American Foundrymen's
Society indicates that portland cement manufactured
with up to 13% of spent foundry sand exhibited
slightly higher compressive strengths than
conventionally produced portland cement, without any
degradation of key characteristics such as set time.
· Mineral Wool Products: Potential silica source.
Flowable Fill: Substitution for regular sand in
flowable fill, a mixture of sand, flyash, and water that
is mixed into a slurry and poured. Flowable fill is a
self-leveling and self-compacting mix that hardens and
develops strength over time, similar to concrete, and is
commonly used as backfill for trenches (sewer,
conduit, utility).
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