Mortar Workability Questions

Mortar Workability Competition Questions

**NOTE: The mix design and cost evaluation must be entered via the ONLINE FORM.  Please refer to the RULES for the most accurate and up to date information.

Q: What means of transportation is recommended to transport our cylinders?

A:  Students have brought their projects as a carry-on (for fear of damage or TSA may possibly remove it from your checked bag.)  However, it is best to check with the laws for your country for transporting your materials. (1)We have seen students use bowling ball style cases to transport some projects; or carry-one suitcase.  Either way, insulation is extremely important. (2) Print a copy of the competition objectives, prizes, and rules from the ACI Website. (3) Print a copy of the ACI Convention Registration Receipt. (4) Print a copy of the ACI Competition Registration Receipt. (5) Print a copy of the list of ingredients used for the project. (6) Print a copy of the Canada Customs letter. (7) To ensure the maintenance of SSD condition for the specimens, teams are encouraged to submerge them in the water before the competition. When traveling, it would be a choice to wrap and seal the specimens with air bubble wrap roll. **The more documentation that you have, the better because customs will not understand why you are carrying concrete around in your luggage.

Q: There are no indicated prices for recycled materials (e.g. recycled glass) in the materials cost. Can we input our own unit cost or is the use of recycled materials not encouraged for the competition?

A: Recycled materials are allowed without hesitation, but we cannot give a cost for every single possible material. The rules state that for “other materials”, the unit cost of the new material should be included in the Appendix, as well as the cost of cement in the same geographical area. The judges will determine a cost based on this documentation.

Q: Are the appendices included in the page count of the paper?

A:  If the Appendix contains the information of new products, such as recycled glass, the information and cost of the material, and cost of cement, it will not be counted towards the page limit. However, any discussion, pictures, mix design sheets, etc., information which should be in the report, if this is put in the Appendix, it will count towards the page limit.

Q: Would there be a disqualification for having a density less than 2.2?

A: There's no density requirement. (1 Failure to include the material properties (density or relative density, absorption for the aggregate, and data sheets for all chemical admixtures and any alternative binder/powder) shall lead to disqualification of the team. Failure to include a correct mix design sheet shall also result in disqualification (Hint: the relative density of a standard mortar should be around 2.2-2.3, unless valid assumptions can be made to have a lower relative density based on the materials added).)

Q:  This years’ competition includes an online form for submitting the mix design and cost evaluation?

A: Yes, this years’ competition includes the online form that must be completed for the mix design and cost evaluation. Please find the link on the Mortar Workability Competition webpage.

Q: Do you want the total cost in $/m^3 AND the total cost of our final batch (for example 650ml)?

A: We want the calculation of the mix design and cost in the report, but the results from the online form will give an indication on the materials used. Final cost will be calculated based on the final mix design used in the competition.

Q: With respect to the substitution content it is described that a maximum of 30% of SCM material and 30% of fillers can be used. So you can use 60% (30% of each) in total, adding up the percentage of these 2 materials, correct? Or the maximum content of both together is 30%?

A: Be careful, the total amount of SCMs and mineral fillers can only be 30% together, you cannot have 30% SCMs and 30% fillers together. In other words, at least 70% of your non-aggregate solid materials should be cement!  You will be unable to submit the mix design online when using 30% SCMs and 30% fillers.

Q: Does the cover page have the same font size setting? And can you leave the name of the institution in Camps Lock, for greater prominence? Can other devices such as italics and bold be used during the report without penalties?

A: You can shape the report to your liking, as long as you follow the formatting of the report as outlined in section A.1 of the rules. There are no rules concerning the use of bold, italic, underlined or caps, as long as items can be easily found in the report

Q: In the abstract are 300 characters with or without space?

A: The abstract is a maximum of 300 words, not characters.

Q: Since there is no mix and cost worksheet anymore we simply need to have the same results as on page 3 of the online Official Mixture Proportioning and Cost Sheet, right? Moreover, do you want the total cost in $/m^3 AND the total cost of our final batch (for example 650ml)?

A: We want the calculation of the mix design and cost in the report, but the results from the online form will give an indication on the materials used. Final cost will be calculated based on the final mix design used in the competition.

Q: All of rules indicate the mix should be for a 1 cubic yard volume, however the online mix cost form is for a 1 cubic meter volume mixture. Should we be developing our mixture for 1 cubic yard or 1 cubic meter?

A: The cost will be calculated for 1 cubic meter of concrete. Appendix C shows the detailed cost scoring mechanism, and the online form will only accept m3. We apologize for the confusion.

Q: Is ground glass considered to be processed aggregate, or is it not permitted? 

A: Yes, you are allowed to use this material, but you need to submit the price for that material and the actual local price for cement (the one you use in their mortar) in your report.  You can calculate cost as: , provided all costs are per ton. Judges will adjust cost if deemed necessary.

Q: Is it confirmed then that the MasterEase will be considered as "High-Range Water Reducer (Polycarboxylate)"?

A: The judging team will verify the selected type of admixture, and in case of any doubts, they will contact the producers in case there is some doubt. However, this cannot happen before the submission of the reports. As organizers, we cannot confirm this as that is task for the head judge.

Q: How do you calculate the "Water in Admixture"?

A: As explained in the rules, for any chemical admixture, 60% of the volume will be counted towards the water content. The online sheet adds this volume automatically to your water content (you don’t need to do this explicitly), and takes the sum of the added water and the water from the admixtures for the calculation of the w/cm.

Q: Is it allowed to use Type I Portland cement in the presentation of white cement?

A. If the cement complies with all specifications, it can be used for the competition. The color does not matter.

Q: Is it allowed to use the Calcium Carbonate (CaCO3) as a mineral filler, that is basically the compound of the known Lime Klin Dust?

A: Yes, you are allowed to use this material. Finely ground calcium carbonate is classified as limestone filler.

Q: Which solid-liquid line is used to determine the Stability score.

A: We measure the lowest line 

Q: How will the mortar stability test be performed? We would like to replicate the test but we do not know if the criteria will be only visual (such as color change and visual appearance) or if the water is removed except for the top of the test tube, and then measure the difference in volume.

A: The verification is visual. The judges will also take pictures before and after for verification afterwards.

Q: What are the dimensions of the funnel used?

A: The funnels used will be standard funnels. We will make sure that the opening of the funnel is larger than the opening on top of the “a” in the ACI mold.

Q: The powdered limestone in the trace formulation will enter as fine aggregate (filler) and should be considered in the calculation of the mass of aggregate (over 60%), correct?

A: Powdered limestone, if I’m correct, has a typical size similar to that of cement, so it will be counted as an SCM or mineral filler, not as a fine aggregate.

Q: In regards to the Official Mix and Cost Worksheet provided to estimate the cost and mix proportions for the competition, it appears that in the chemical admixtures section that no admixture contribute to the volume of the mixture. Is that correct?

A: The volume calculation seems to be fine. It takes the water (without the contribution of the admixture) and the total volume of admixture into consideration. We found an issue with calculating the mass of water from the admixture, and the w/c goes through the roof, but have corrected it.  Please be sure to list the relative density of the material as well. If this is not filled out, the form does not adjust anything.

Q: Should the sieve mesh described in the competition appendix following the ASTM C33 standard explicitly follow this standard? Even if we use very fine sand that meets the fineness modulus of the regulation (2.3 to 3.1) and does not fit for "lack of" aggregates of size 1.18 and 2.36, is there any caveat for this track?

A: The sand needs to comply with the grain size distribution range provided in ASTM C33.

Q: With respect to the sieve value ranges following ASTM C33, should the analysis be made for each material constituting the mixture or can I compose combinations between two or more different sands in order to arrive at such characteristics?

A: The combination of sands should comply with the grain size distribution. Describe the process of combining sands in the report, with their sources and ratios. For the mix design and cost sheet, list each material separately with its source and grain size distribution and whether it is natural or crushed (manufactured). The sheet should be able to give you the combination. Try this before the deadline to see if there are any issues. The mix design sheet does not allow submission of something is out of specification. 

Q: Can sand from quartz crushing be used? 

A: If the sand is the result of a crushing operation or any other process altering the grain size distribution (other than sizing and sieving), the sand is considered as a manufactured sand. You are allowed to use this crushed quartz sand.

Q: The ratio water / cm (cement + mineral fillers) can not exceed the ratio 0.5. At this stage it should be considered if you use an SCM material or cement as a factor to be considered in that formula, right? Still in relation to this stage for the consideration of the fillers, the materials must pass through the ASTM 200 sieve. We will then need to characterize this fine sand data, since it contains material passing through this sieve and this must be discounted, that is, it must be treated as material filler and no longer as part of the sand since it is a powder?

A: Yes, the w/cm is calculated relative to the amount of cement and SCMs. Anything which is considered as an SCM should pass through a #200 sieve. For the sand, ASTM C33 specifies that maximum 3.0% can pass the #200 sieve for a natural sand, which is amplified to 5.0% in case of crushed sand. If your sand contains more than these percentages of fines, you should wash the sand to get below this threshold limit. If your sand is below this threshold, the material passing #200 will be considered as sand, and will count towards the total sand content, but it cannot be used as a mineral filler to calculate the w/cm. If you want to consider the particles passing the #200 sieve as a mineral filler, these should be bagged individually as a separate material. Their mass can be used for the calculation of w/cm, but it will not be counted towards the total sand content. Most likely, judges will qualify this material as a mineral filler similar to limestone filler, with a price of $40/ton.

Q: For the SSD condition, does it have to be considered in the ratio W/C or it is considered apart?  Does the chemical admixtures have to be considered in the ratio W/C or not, because in the forum it’s written that it is apart?

A: The mix design, and thus the calculation of the w/cm is based on the aggregates in SSD condition. In the competition, the aggregates shall not be above SSD condition. The w/cm cannot be corrected for aggregates below SSD condition.  For the second question, it seemed like old FAQs related to the previous competition were posted. These are removed from the FAQ section. For clarity, the water content of the admixtures (60% of its volume) is counted towards the w/cm.

Q: Can I use activated clays and does the chemical additive must be used in the base cylinder (BCS) and in the alternative cylinder (ACS)? Or can we use it only in the alternative?

A: Activated clays are allowed and their chemical compositions and physical properties shall be detailed in the MTDS. In addition, the environmental impacts of the activated clay (in terms of required heating energy and electricity) shall be quantified in the Tool with proper references and discussed in the report. Adding a figure to the report and poster is recommended to clarify the calcination process of the clay.  Chemical admixtures can be used in both or just the ACS mixture.

Q: Stability will be tested via the ratio of the solid liquid line after 30 min of rest relative to initial volume?Does stability mean the ability of the mix to stick to the mold? 

A: The stability relates to the mixture being able to keep the solid particles in suspension. If the mixture is unstable, sand particles, and potentially even cement or other small particles will sink with time. This will deliver a clear separation line in the graduated cylinder. This line will be recorded for stability. 

Q: Will the pre-weighed bags be measured by grams or by mL?

A: Any solid material will be weighed (in g or kg). Liquid materials will be measured by volume (ml).

Q: For the mortar workability competition, I was just confirming the w/cm ratio meaning. Does this mean if my mix has 8% concrete by mass, it can only have 4% water by mass?

A: The w/cm is the mass ratio of water (including a portion of the water in the chemical admixtures) to the mass of cement and all cementitious materials. This ratio shall not be larger than 0.50 for this competition. This ratio does not include the mass of aggregates. However, the rules also state that the mass of aggregates shall be at least 60% of the (total) mass of mortar.

Q: What if a team can’t obtain pure Portland hydraulic cement, and the majority of the cement existing in our country (Costa Rica) exceeds the requirement of 30% SCM?  Also, we have a type of white hydraulic cement which is only composed by clinker and plaster. Can this be used?

A: Teams must use C150 portland cement if it is available. In markets where C150 is not available, blended cement meeting C595 may be used but with maximum SCM content of 30%. SCM content in excess of this will result in disqualification. 

Q: Can 1 team from the same school participate in both student competitions in Spring 2019, Quebec, Canada?

A: Yes! EcoConcrete requires a minimum of 1 team member be present at the competition and Mortar Workability requires 2 team members be present at the competition.  Thus, as  long as 3 team members can attend the competition in Canada, you may participate in both.  The entire team members who make up each team for Eco & Mortar may be alike.

Free Student Membership

Learn more about ACI’s free student membership and the many related benefits.

Learn More About Student Membership »

Attend the ACI Convention

The ACI Convention features a full-slate of student events - attend committee meetings, technical sessions, tours, and networking events offered throughout the convention.

Learn More About the ACI Convention »

Edit Module Settings to define Page Content Reviewer