Pervious Cylinder Competition Questions

Q: Are we restricted to working on pervious concrete or can we also work on pervious geopolymer concrete?

A: While the committee is interested to see creative solutions to the competition, we are afraid that geopolymer concrete is not acceptable in the competition this year. Section 2 of the rules do mention that exceptions to cementitious components can be made on a case-by-case basis; in this case, geopolymer binders are not allowed. However, the rules for the next competition will consider this option seriously.

Q: Is it ok for us to use an amount of cement below 270 kg/m3?

A: Allowable mixture components are detailed in Item 2 of the rules. There are no limits placed on minimum or maximum mixture contents in the rules.

Q: How will the cylinder diameter be measured?

A: The diameter is measured with calipers.

Q: Will the cylinder be wet or dry for splitting tensile test? What condition will the testing cylinder be between infiltration and splitting tensile test? Will it be drying in between (if so, how long), or is splitting tensile testing immediately after infiltration?

A: All teams will be treated with the same conditions. The current plan will be to have all specimens kept in a wet condition with damp towels while they are on deck to test. Split tensile testing is performed immediately following infiltration, but the several-second infiltration time typically results in a bit of a wait at the testing machine.

Q: We'd like to ask you if it is ok to use instead of the regular lime stone aggregates, aggregates made from fly ash we prepare them at our lab.

A:Allowable mixture components are detailed in Item 2 of the rules. The use of any component that does not meet these requirements subjects the team to possible penalty or disqualification.

Q: Is there a problem if the complementary Units Conversion Page is unused?

A:The Units Conversion Page on the Official Mixture Design Spreadsheet is an additional helpful page for non-SI students. It will not be reviewed as part of the judging process and does not need to be populated.

Q: Can you send us all the pieces and sizes of the permeameter (dimensions) that you will use on the competition?

A: McMaster-Carr
3 in. gate valve - 3999K22
12 in. long 4 in. ID acrylic: 8486K577
Quick-release worm clamp: 5588K12
Tire inner tube: 4991T33

Home Depot:
4 in. flex coupling
3 in. to 4 in. flex coupling
3 in. street elbow

American Cube Mold:
Rubber bands - These are 1/2 in. in thickness and orange - I believe they are synthetic rubber and have a higher durometer than typical rubber bands
3 in. ACM1K-3
5 in. ACM1K-5

Q: What's the granulometric composition that the permeable concrete must have for the competition?

A: I believe you are asking about the required gradation of the aggregate for pervious concrete. Aggregates shall meet the rules, notably item 2.b., but there are no requirements for the gradation of the material; however, it must be measured and reported. ACI 522 offers guidance on aggregates for previous concrete mixtures.

Q: Can you send us the paper about the design prices?

A: While previous competitions included cost as a portion of the competition, that section has been removed. Please ensure you are using the correct version of the rules — read this PDF.

Q: Is the cylinder cut the day of the competition or do we have to cut before the competition? Also, do you have more information about the permeability test?

A: No, the cylinders should be fully prepared and in a dry condition at check-in the morning of the competition. We will not have equipment available for concrete sawing or cutting at the competition. The permeability test is a falling head infiltration test as described in the rules item 5.c.iii. The chamber is 4 in. ID and flow measured from 9 in. above the specimen until the water level reaches 1 in. above.

Q: I have a question regarding the acceptable mixture materials within the mixture design. The team was considering to use nanoparticles in the mixture. Is this acceptable within the rules? And if so, are there any restrictions within the material because nanoparticles vary in composition?

A: All mix ingredients would need to meet the requirements of section 2 of the rules. The applicable section depends on the use and properties of the material. An inert nanomaterial would need to meet the requirements of an aggregate and be included in the gradation. Pozzolanic nanomaterials such as colloidal silica would need to meet the requirements for cementitious and supplementary cementitious materials.

Q: Our team is considering to use a product called “colloidal nano-silica” as per the attached data sheet. The product has the same chemical composition as liquid silica fume, except that the size of silica particles is smaller. Would using this product be acceptable in the competition?

A: According to the rules, section 2.c., colloidal silica would be acceptable if it meets ASTM C1240.

Q: Are we allowed to use latex for the pervious concrete cylinder competition?

A: Materials used for the pervious concrete mixture must meet the requirements of section 2 of the rules. Section 2.d. lists the acceptable chemical admixtures, so any used would have to meet the requirements of that section.

Q: My admixture (aggregate, fiber) is XXXXXX. Is that acceptable?

A: Allowable mixture components are detailed in Item 2 of the rules. The use of any component that does not meet these requirements subjects the team to possible penalty or disqualification.

Q: What is the loading rate for the splitting tensile strength test at competition?

A: ASTM C496 specifies a load rate of 0.7 to 1.4 MPa per minute; however, this should be considered a minimum rate for the competition. Actual load rate will depend upon the total number of specimens and an estimated total strength to ensure that all specimens can be tested within the competition window on Sunday.

Q: What is on the parts list of the falling-head permeability test for this year's Pervious Concrete Competition?

A: Pervious Infiltrometer parts list – part # and source given for example. Similar parts may need to be sourced differently outside the United States.

3" gate valve - McMaster-Carr part 3999K22

12" long 4" ID acrylic tube - McMaster-Carr part 8486K577

Quick-release worm clamp - McMaster-Carr part 5588K12

tire inner tube (to cut up and use to seal specimen into assembly) - McMaster-Carr part 4991T33

4" flex coupling (available from most home improvement stores)

3" to 4" flex coupling (available from most home improvement stores)

3" street elbow (available from most home improvement stores)

½” Rubber Bands of synthetic rubber - American Cube Mold part ACM1K-3

PVC Shrinkwrap film – 10” (to wrap the specimens – use 2 meter long piece) part DU-PVC-355-10 from US Packaging and Wrapping

Sample suppliers:

American Cube Mold:
PVC Shrinkwrap film:

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