ACI Eco Concrete Competition Questions

**NOTE: The objectives listed on our web page have been updated to correspond with the rules. Please refer to the RULES for the most accurate and up to date information.

Q: The competition rules states that content of coarse aggregate (above 5 mm) should by more than 30%. Could We estimate the border point of coarse aggregate (5 mm) based on European size sieve analysis? We can use the standard grading chart and calculate the amount of aggregate above 5 mm in very simply way.

A: The volume of aggregates with sizes larger than 5 mm shall be more than 30% of the total volume of aggregates. This should be reflected in the mix design table (where the mass of constituents for one cubic meter of mixtures stated). Reviewers can be able to recognize the volume of coarse aggregates based on the specific gravity of the constituents as well as the corresponding graphs of the sieve analysis.

Q: The software for Eco's Mix Design does not allow us to change the type of coarse and fine aggregate.

A: The primary coarse and fine aggregates as well their transportation distance to the plant will be fixed in both scenarios to keep the consistency of primary materials suppliers. Nevertheless, teams can add new rows by clicking on the “green +” sign next to “Aggregates” to define the alternative aggregates, such as recycled aggregates. You can find an example of defining recycled aggregates in attached screenshot. In this example, it is assumed that 100% of the primary aggregates is replaced by the recycled materials and therefore, the mass of primary aggregates in the ACS sheet is zero. However, this replacement can be partial. It should be noted that the transportation distance from the landfill to the recycling plant and from the recycling plant to the concrete plant (in this competition, it is assumed as the University location) shall be included in the appropriate places. The quantity of electricity and/or heat required to process the recycled materials (e.g. crushing, sieving, etc.) shall also be considered in the calculation for each recycled material.

Q: Can we assume that our BCS and ACS should have the same mass?

A: The BCS and ACS mix designs usually have different unit weights. As for one cubic meter mixture, the masses would be different. Further discussion of the design of concrete mixtures, incorporating various alternative materials, with team advisor or mentor is recommended.

Q: Are we supposed to use the quantities that are already in place on the Calculation Tool spreadsheet as our Base-case Scenario or are we suppose to develop our own unique Base-case Scenario?

A: The BCS mix design and curing condition shall comply with the rules specified in Section 2.3-2.5. The default values of the mixture constituents can be adjusted according to these rules.

Q: Should the total volume of our mixture be taken into consideration with regards to reduction?

A: The replacement of various alternative materials, which have different unit weights than primary materials, can eventually alter the unit weight of ACS compared to BCS. Teams shall mention the mass of constituents for one cubic meter of concrete mixture in the spreadsheet, the report, and the poster. In fact, one cubic meter of ACS shall be compared to one cubic meter of BCS.

Q: Can we use the Vancuver style for textual citations?

A: Following citation styles can be used in the report and poster. One citation style shall be consistently followed for all the references. (MLA, APA, Chicago, Harvard, Vancouver)

Q: From System Boundaries under LCA section, do we need to make a similar figure (1) for each material?

A: One system boundary for each case is enough to include all the cradle-to-gate processes. The dash line box in Figure 1 delimits the system boundary explained in Section 2.5. Therefore, all the processes located inside the box are included in the system boundary of this system analysis (For more information, you may refer to ISO 14044).

Q: Should the graduate student who’s assisting us be added as a “team member?”

A: Each team can ask the help of one graduate student (Ph.D. or master student) to participate in the mix design and the simplified life-cycle assessment (LCA), and the student shall be mentioned in the report. It means that jury members can recognize the name of the graduate student in the report. They should not be added as a member of the team.

Q: We would kindly like to know the composition of cement classified as normal type I. Are all the materials corresponding to this cement clinker + gypsum? Also, Cement Type II - Moderate Resistance to Sulphate and Type V - High resistance to Sulfate are present in the ASTM nomenclature. In the NBR (Brazil) standard, we only have the type of cement with resistance to sulphate. What is the difference between the types of cement with sulfate resistance of the American standard? So that we can evaluate the choice of our material.

A: The C150 standard addresses the chemical and physical properties of these portland cements. Teams are encouraged to read those specifications to understand if their portland cement are complied with the limitations of the standard. In fact, if there is a portland cement in Brazil with the similar specifications of type II, this team would be free to use it for the eco concrete competition. It should be kept in mind that blended cements are prohibited to use in the BCS.

Q: Is it possible to get a Calculation Tool file in the US system of units (lbs, ft, etc.) for the Eco Concrete student competition?

A: It was decided we would standardize the use of SI units, as accommodating dual units has imposed quite a challenge (especially for prices per ton, and for cost relative to concrete volume). In addition, the US metric is not defined for the environmental impact assessment, such as ecotoxicity and carcinogenic. To keep it constant, we went for the SI metrics.

Q: I could not find the location option for Bangladesh in the Life 365 software. Would you please guide us on how to proceed in this regard?

A: Please refer to section 2.5 of the rules for the default selections in the Life 365 tool.

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