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: 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.