Cement and Concrete
Coal fly ash, ground granulated blast furnace (GGBF) slag, cenospheres, and silica fumes are recovered materials that are readily available in some areas for use as ingredients in cement or concrete. Coal fly ash is a byproduct of coal burning at electric utility plants. Slag is a byproduct of iron blast furnaces. The slag is ground into granules finer than Portland cement and can be used as an ingredient in concrete. Cenospheres are small, inert, lightweight, hollow, glass spheres that are a component of coal fly ash. They can be added to cement to produce a specialty, high performance concrete. Silica fume is a waste material recovered from alloyed metal production. It can also be added to cement to produce a high performance concrete.
- Recommended Recovered Materials Content Ranges
- Product Specifications
- Product Information
- Additional Links
EPA recommends that procuring agencies prepare or revise their procurement programs for cement and concrete or for construction projects involving cement and concrete to allow the use of coal fly ash, ground granulated blast furnace slag (GGBF slag), cenospheres, or silica fume, as appropriate. EPA does not recommend that procuring agencies favor one recovered material over the other. Rather, EPA recommends that procuring agencies consider the use of all of these recovered materials and choose the one (or the mixture of them) that meets their performance requirements, consistent with availability and price considerations. EPA also recommends that procuring agencies specifically include provisions in all construction contracts to allow for the use, as optional or alternate materials, of cement or concrete which contains coal fly ash, GGBF slag, cenospheres, or silica fume, where appropriate. Due to variations in cement, strength requirements, costs, and construction practices, EPA is not recommending recovered materials content levels for cement or concrete containing coal fly ash, GGBF slag, cenospheres, or silica fume. However, EPA is providing the following information about recovered materials content.
- Replacement rates of coal fly ash for cement in the
production of blended cement generally do not exceed 20-30
percent, although coal fly ash blended cements may range
from 0-40 percent coal fly ash by weight, according to ASTM
C 595, for cement Types IP and I(PM). Fifteen percent is a
more accepted rate when coal fly ash is used as a partial
cement replacement as an admixture in concrete.
- According to ASTM C 595, GGBF slag may replace up to 70
percent of the Portland cement in some concrete mixtures.
Most GGBF slag concrete mixtures contain between 25 and 50
percent GGBF slag by weight. EPA recommends that procuring
agencies refer, at a minimum, to ASTM C 595 for the GGBF
slag content appropriate for the intended use of the cement
- According to industry sources, cement and concrete
containing cenospheres typically contains a minimum of 10
percent cenospheres (by volume).
- According to industry sources, cement and concrete containing silica fume typically contains silica fume that constitutes 5 to 10 percent of cementitious material on a dry weight basis.
Cement and concrete containing coal fly ash can be ordered through the General Service Administration's (GSA's) online ordering system. In addition, GSA publishes various supply catalogues, guides, and schedules for recycled-content products available through the Federal Supply Service.
Buy-Recycled Series: Construction Products (PDF) (11 pp, 104K, About PDF)
This fact sheet highlights the construction products designated in the CPG, including cement and concrete containing recovered materials, and includes case studies, recommended recovered-content levels, and a list of resources.
Technical Background Documents
Technical background information on cement and concrete containing coal fly ash was published in the Federal Register on January 28, 1983 (48 FR 4230) and codified at 40 CFR 247. You can view this document at the RCRA Docket in Washington, DC. To obtain the address of the Docket and make an appointment, call 202 566-0270. This product designation was one of five incorporated in CPG I/RMAN I on May 5, 1995 (60 FR 21370-21386). Technical background information on cement and concrete containing cenoshperes and solica fume can be found in the Background Document for CPG IV/RMAN IV.