The Slag Cement Association (SCA) commissioned the Athena Institute to produce this Ready Mixed Concrete Life Cycle Assessment (LCA) Calculator for Slag Cement - Version 1.0 to show the impacts of using slag cement in ready mixed concrete.
The LCA calculator allows you to enter custom concrete mixes and then substitute varying amounts of slag cement through a simple dashboard interface. You simply select a preset mix or enter the details of a custom mix and the calculator will allow you to increase or decrease the percentage of slag cement and calculate LCA results in real time. The tool also allows you to compare custom mixes against region-specific industry average mixes and to substitute these mixes into a generic whole building to calculate cumulative whole-building results.
Registration is required to download content. Registration information is used by the SCA to track use and will not be distributed to any third party.
Please review additional information below for instructions and frequently asked questions.
The calculator is based off of LCA work previously completed by the Athena Institute for the National Ready Mixed Concrete Association as a part of Version 1 of their Industry-Wide EPD initiative. The complete documentation of Version 1 this LCA work can be found here: http://www.nrmca.org/sustainability/EPDProgram/#IndustryWideEPD.
The LCA report that accompanies the EPD documents all data and modeling decisions used to produce those results. Since Version 1 was completed, several of the datasets have been updated. Most notably, the portland cement and slag cement profiles are now based on more recent data. The updated data sources are as follows:
Portland Cement: Portland Cement Association EPD of Portland Cement—Published by ASTM International.
Slag Cement: Slag Cement Association EPD of Slag Cement—Published by ASTM International.
High-Range Water-Reducing Admixture: EFCA EPD for 324 Plasticiser—as per the Carbon Leadership Forum PCR for Ready Mixed Concrete.
It is imperative that the user of the tool only enter realistic concrete mixes for a given strength class. No validation exists within the calculator to test whether a given mix is equal to the strength claimed. It follows then that any comparisons to strength class benchmarks may be invalid if the entered mixes or slag cement substitution amounts do not result in a mix that is equal to the claimed strength.
It is also important to note that the impacts presented in this calculator are only in absolute terms (i.e., kg CO2eq.) or relative to a benchmark design (i.e., 90%) but do not give an indication as to severity. It is widely accepted that some impacts, and particularly ozone depletion, are relatively insignificant. Ozone depletion results in particular are subject to significant uncertainty as the overall scale of these impacts is so small that trace amounts that are correctly or incorrectly included in background data can skew results.
Organization of Calculator/Use
The calculator is separated into four worksheets. Upon opening the calculator, you will be prompted to read and accept the terms and conditions. Scroll to the bottom of the page and select accept to view the four worksheets.
This main dashboard tab allows you to select from a list of preset concrete mixes and to then alter the percentage of slag cement in that mix. A graph on this tab shows the environmental impacts of the baseline and slag-modified mixes in real time. The tab also allows you to select the North American industry average region "NRMCA" or a specific North American region to apply region-specific supply chain characteristics.
This tab allows you to enter up to 10 custom mixes that will then be available from the drop-down list on the "Slag Substitution" tab. The environmental impacts of these mixes are also calculated and shown on the "Comparison to Benchmark" tab. Benchmarks were not available for every potential strength class, so to be conservative the comparisons revert back to the next highest strength class for which results are available. The available strength classes for the purposes of benchmarking are 2500, 3000, 4000, 5000, 6000, and 8000 psi. If the strength class of a custom mix is 3500 psi for example, enter the strength as 3000 psi, which is the closest conservative benchmark.
Comparison to Benchmark:
This tab shows environmental impacts of the entered "Custom Mixes" in absolute terms and as a percentage of region-specific industry average benchmarks. The tab shows this comparison graphically so that you can easily see which mixes are lower than the industry average benchmarks in at least three categories and thus would qualify for LEED optimization credits.
Impacts in Whole Building:
This tab allows you to enter amounts for each of the "Custom Mixes" used in a given project to calculate the cumulative whole-building impact. The calculator adds in non-concrete impacts (i.e., steel, glazing, insulation, etc.) in amounts proportional to the amount of concrete. Since the non-concrete portions are not specific to a particular building, the results in this tab are not considered a whole-building LCA, but do give you a realistic look at how concrete selection effects whole building impacts. Further, the impacts shown on this tab are "embodied" or "material" impacts only, which means that they do not include the impacts from heating and cooling the building during its use phase.