Industry-Average Impacts of Concrete Revealed in EPD
The National Ready-Mix Concrete Association has released an environmental product declaration (EPD) showing average cradle-to-gate impacts of a variety of concrete mixes nationwide and by region. The document makes it easier for project teams to assess the environmental impact of one of the most common building materials and also paves the way for individual manufacturers to release product-specific EPDs for comparison with the industry average—a step incentivized under a new Materials and Resources credit in LEED version 4.
The EPD covers 48 ready-mix concrete products that are used in residential, commercial, and public construction. The products range from a compressive strength of 2,500 pounds per square inch (psi) through 8,000 psi and contain different mix components, including fly ash, slag cement, natural and crushed aggregates, admixtures, and batch water.
A user can see, for example, that the average global warming potential per cubic meter for concrete within the range of 2501 to 3000 psi with limited or no fly ash or slag content is 337 kg of CO2-equivalent, while concrete with the same compressive strength containing 30% to 39% fly ash has a significantly lower impact—265 kgCO2. (For more background, see Reducing Environmental Impacts of Cement and Concrete).
The EPD does not take into account environmental consequences from transportation to the construction site, onsite processes and components, or end-of-life disposal. However, since more than 85% of North American concrete plants use trucks that mix concrete after they are loaded at the project site, a portion of the trucks’ energy use is factored into the manufacturing impact calculations.
Published December 23, 2014