Recycled Concrete Cylinder Competition

In this competition, teams will design a sustainable, lightweight, and efficient concrete mixture and cast two (2) cylinders from this mixture as per the specifications below.  Each cylinder will be weighed and tested in compression.  Each team will be scored on the average stiffness to weight ratio, the average strength to weight ratio, and the average ratio of the volume of recycled materials to the volume of the cylinder.  Slump shall be self-reported and fall with a 3 inch +/- 1 inch tolerance.  Each cylinder must be at a maximum age of 14 days.

 

The recycled concrete cylinder competition will be held using the following rules.  Any entry that does not conform to the rules will be disqualified at the judge’s discretion.

 

1.1 Design Specifications

The following design specifications will be examined either before or after testing, as appropriate:

• Each cylinder must be nominally 3 inches by 6 inches.  Any cylinder not meeting ASTM C39-14a will be rejected.  The cylinders will be tested using removable steel caps to set the cylinder in place in the testing machine.

• Any cylinder not within 2.9 and 3.1 inches in diameter and 5.9 and 6.1 inches in height, inclusive of any capping compound used, will be disqualified.  The diameter shall be calculated according to ASTM C39-14a.

• Cylinder must follow the material specifications outlined in Section 1.2.

• A mixture design report must accompany cylinder following the formatting guidelines listed in Section 1.4.

• Cylinder will be tested in accordance with Section 1.3. If there is an equipment problem that prevents Section 1.3 from being followed, the test plan will be modified to allow for the test to be run and each entry will be tested with the new regime. If the equipment problem occurs during the competition, the judge will make a determination on how to continue while being fair to each entry.

• In all cases, the judge’s ruling is final

 

1.2 Material Specifications

 

1.2.1 Aggregates

All coarse aggregates must be replaced by any type of recycled material.  This recycled material can be any material to be used as some type of recycled replacement material.  This can include glass, rubber, recycled concrete (even though recycled concrete contains coarse aggregate, its use is still permitted), asphalt, etc.  Fine aggregates must be sand (not recycled material) as defined by ASTM C33.

 

Any coating or chemical treatment applied to the aggregates must be accounted for in the mixture design report.

 

1.2.2 Cement and Cementitious Materials

Any type of cement or cementitious material at any proportion may be used in the competition.  This includes common cement and cement replacement materials such as Portland cement (any type), fly ash, ground granulated blast furnace slag (GGBFS), and silica fume.  Less common cementitious materials may also be used, including recycled materials.

 

1.2.3. Admixtures

Any admixture(s) may be used in the concrete mixture.  All admixtures shall be included in the mixture design report.  Water from admixtures must be accounted for in the mix calculations.  The manufacturer recommended dosage range of each admixture should also be reported in the mixture report.

 

1.2.4 Epoxy and Other Confining Reinforcements

The cylinder surface must be concrete only.  No epoxy, fiberglass resin, or other coating material may be applied to the surface.   Discrete wires, threads, or meshes are also not allowed on the cylinder’s surface and are only allowed internally if they are part of a recycled aggregate.

 

1.2.5 Fibers and Other Reinforcing Materials

Fibers and other reinforcing materials of any kind are not allowed in the concrete mixture.

 

1.2.6 Specimen Preparation

The specimen must be made in accordance with ASTM C192-13 §7.3, ASTM C1176-08, or ASTM C1435-08. Any attempts to create a “structure” will result in the immediate disqualification of the entry.

 

The specimen may be cured in any manner but must be indicated on the design report.  In addition, the specimen must be at room temperature when tested.  Excessively cold or hot specimens will be disqualified.  Specimens may be wet, with water, during testing.  The slump shall be self-reported on the design report.  The slump must be 3 in. +/-1in.  Points will be deducted if a mix does not meet the designated slump tolerance.

 

1.3 Testing Regime

 

1.3.1 Compressive Test

Each team will weigh their cylinders on a scale and record each cylinder’s weight before the testing begins.  The testing regime will follow ASTM C39-12a.  Teams will place their cylinder into the test machine and position it as they wish.

 

The testing machine will apply a steadily increasing load on the specimen until failure.  The extensometer will be added to the cylinder before the test begins then removed once the strain in the cylinder exceeds 0.0004.  While the extensometer is removed, the machine will maintain its current load without increasing, and once it is completely removed, the operator will continue the machine at a steady loading increase.  Loading will then continue until failure.  Failure will be defined as the point when the load drops more than 20% from the maximum load.  It is each team’s responsibility to ensure the capping or grinding is done properly to prevent premature failure.  Unbonded caps will be used to test each cylinder, so each group needs to ensure proper capping or grinding to maintain a level surface.   Strain will be calculated by the stiffness value using the stress and strain at 0,0 and the stress that corresponds to a strain of 0.0004.

 

1.4 Design Report

The design report consists of a single mixture design table.  This table is heavily influenced by the concrete canoe mixture design table released by ASCE.  A 20% deduction will be applied if the design report is not completed properly.  This will be at the discretion of the judge.

 

Make sure to include in the design report the self-reported slump of the mixture design as well as how sustainable the mixture design is.  In other words, why are the replacement recycled materials sustainable?  Each report shall be a maximum of 1000 words with a description of how the final mix design was reached.

 

The design report is due on March 31 at 11:59 PM.

 

1.4.1 Density Measurement

There are several ways to measure density of fresh and hardened concrete.  The density must be measured with one of the standards below and indicated in the design report:

 

• ASTM C138-13

• ASTM C567-11

• ASTM C642-13

• ASTM C1040-08

• ASTM C1170-08

 

1.5 Scoring

Each team will receive points as to where they ranked in each of the following average calculations between the two (2) cylinders: stiffness to weight ratio, the strength to weight ratio, and the volume of recycled materials to volume of the cylinder.  These equations can be found below.  The team with the best ratio in each category will receive the most points, and each subsequent team will receive one less point.  The team with the most points after all calculations will be declared the winner.  The design paper is required but does not contribute positively to a team’s score.  However, failure to submit a design report, or submitting a design report with errors, will cause the team’s score to decrease by 20%.  Teams will also lose points of the mix does not fall within the slump tolerance of 3 +/-1 inches.