• To reduce the carbon impacts of CMU, the two primary options are to reduce the total amount of materials used and to reduce the portland cement content.
  • To reduce the material quantities, use ASD or SD methods and don’t rely on empirical design or rules of thumb; consider alternatives to fully grouted walls or overly reinforced CMU walls.
  • A few CMU manufacturers have achieved portland cement reductions by replacing a portion of the portland cement with supplementary cementitious materials (SCMs) such as fly ash and slag cement. SCMs may also be added to mortar and grout in place of cement during construction.
  • Specify the prism strength method rather than the unit strength method when specifying the compressive strength of masonry. The prism strength method typically results in higher strength values which can significantly lower amounts of portland cement in the masonry units and grout mix compared to the unit strength method.
  • See the SEI Technical Report Structural Materials and Global Climate for further information.
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