Construction and demolition waste material in America is around 136 million tons per year, or about 3 lbs per person, per day. Recyclable materials such as concrete and aggregates can be recycled at the end of their serviceable life as a buildings, pavement, driveways or other structures – limiting the quantity of waste concrete and aggregates that is land filled and reducing the requirement for new Recycled Concrete materials in new concrete construction projects.

The components of concrete may be recycled materials, and concrete as well may also also be recycled, these materials are commonly accessible locally. Almost all concrete in urbanized areas is recycled as fill or road basing and not sent to a landfill. Concrete composition taken from destroyed structures can also be recycled to protect shorelines, etc.

Wood and steel concrete forms are recycled once they become old or out dated. Just About all rebar is derived from recycled steel. Most all cement plants incinerate waste derived fuels such as spent re-solvents, old oils, and tires.

Recycled concrete can be utilized as aggregate in new concrete mixes, particularly the coarse aggregate portion. While utilizing recycled concrete as aggregates, the following should be considered:

• Recycled concrete as aggregate can commonly have a higher absorption and a lower specific gravity then a natural aggregate source and will produce concrete with a little higher drying shrinkage and creep potential. These differences can become greater with an increased amount of recycled fine aggregate.
• Too many recycled fine aggregates can also produce a harsh and unworkable mix. Many DOT’s have observed that using a mix with 100% coarse recycled aggregates, but only around 10% – 20% recycled fine aggregate, works well. The remaining percentage of fines is natural sand.
• In pulverizing the concrete, it becomes difficult to control particle size distribution, meaning that the “aggregates” may not meet grading requirements for ASTM C33 – “Standard Specification for Concrete Aggregates”.
• The chloride content of recycled aggregates is also a concern if the recycled concrete will be used in steel reinforced concrete. This is especially an issue if the recycled concrete is from pavements in northern most climates where road salt is utilized seasonally. The alkali content and type of aggregates in the system is likely unknown, and therefore if mixed with undesirable materials, a chance of alkali-silica reaction is potential. Recycled Concrete

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