Every Step Matters: Blended Cements

Jan 9

The United Nations and Intergovernmental Panel on Climate Change both stress the critical importance of achieving a 65% reduction in global emissions by 2030 to achieve safer levels of carbon emissions and a healthier climate for our future.

Motivation

These goals have inspired bold commitments from Architecture 2030 to reduce the global warming potential of materials by 65% or better by 2030 and to zero by 2040. Further, SE 2050 commits to eliminate embodied carbon in projects by 2050.

The California cement industry has committed to carbon neutrality by 2045.

Small Changes Make a Big Difference

As the foundation of modern society, concrete is the most widely used construction material on earth. No alternative building material can contribute as much to meeting the needs of the increasing global population and urbanization.

The concrete formulation itself can provide significant climate change mitigation. Even small changes to its formulation can dramatically affect the construction industry’s carbon footprint over time.

By including blended cements in concrete specifications, architects and engineers will enable game-changing reductions in CO2 emissions.

Blended Cements

Blended Cements are mixtures of Portland cement and other materials and are specified under ASTM C595 and AASHTO M240. These specifications include 4 types:

IL - Portland Limestone Cement (PLC): blends of Portland cement and Limestone

IP - Portland Pozzolan Cement: blends of Portland cement and pozzolans like Fly Ash or Natural Pozzolans

IS - Portland Slag Cement: blends of Portland cement and Ground Granulated Blast Furnace Slag

IT - Ternary Blended Cement: blends of Portland cement and 2 of the above materials

For each type of blended cement, the manufacturers report the amount of replacement material by putting a number in parentheses in the designation of the finished product. For example, a Type IL (13) contains 13% limestone in the finished cement.

Measuring Impact of CO2 Savings

By reviewing an Environmental Product Declaration, a determination can be made of how much carbon is being avoided through using blended cements.

Combined Carbon Reduction Potential

There are many ways to reduce the carbon impacts of concrete. Mix designs with blended cements are compatible with other Supplementary Cementitious Materials (SCM) to further reduce carbon in the finished concrete.