Building Good Boxes ACPA Spring Short Course School Presented by Dave Tuchscherer and Chad Wilson ACPA Spring Short Course School Houston February 11-14, 2014 www.concrete-pipe.org

We will discuss both wet cast and dry cast techniques. 2 This session is designed to pass on some production concepts that will help you to build better boxes. We will discuss both wet cast and dry cast techniques. www.concrete-pipe.org

Mold Setup -Always try to use larger sized “filler” extensions. -Watch vibe mounts. Ex. – Odd size fillers vibes are high Even size fillers vibes are low -When switching box sizes, clean out between extensions every time. www.concrete-pipe.org

Mold Setup Jacket Bracing Bar welded to Jacket for Bracing www.concrete-pipe.org

Mold Setup Alternating Vibe Heights Clean and Greased Using expanding foam spray can help prevent build up over a long run. www.concrete-pipe.org

Mold Setup Regularly check for wear on pallet feet of jacket. Know what it should be per manufacturer and what you are at. www.concrete-pipe.org

Cage Production -Measure mesh sheets when starting cage production. Check for differences in total length. -Jig pallets are extremely useful if possible. -Take into account thickness of reinforcement when setting up jig. -If time allows, produce one cage and test fit it in your mold to allow for adjustments. Check clearances and sturdiness of cage. -Create a standard operating procedure specific to your facility on how to find bend points and put the cage together. www.concrete-pipe.org

Cage Production -Use the right number of cage spacers. -Look for bowing in cage, not maintaining clear, etc. -Too many spacers can become costly, too few can leave you with a cage that will distort while in transport. -Place spacers within top and bottom 6” of cage. -Placing spacers in the haunches before tying the cage together can help keep it square during the rest of the process. Basement straps placed around the bottom of the cage and pallet keep the cage from moving during strip process. www.concrete-pipe.org

Cage Production Pallet specifically used for cage production. www.concrete-pipe.org

Cage Production Using The Correct Number of Spacers Before After www.concrete-pipe.org

Cage Production Cage Holding Device Strap Holds cage in place during stripping process. Cut off exposed strap next day when tipping out. www.concrete-pipe.org

Cage Production Welded bar used to space cages before assembly. Stops welded on bender to help accuracy of bends. www.concrete-pipe.org

Cage Production This box is subject to rejection by an inspector due to insufficient reinforcement clearance. www.concrete-pipe.org

Dry Cast Concrete Using a “soap” admixture specific to dry cast concrete production can enhance product appearance and strength. Ask your admix provider for details. -Develop or use an existing slump measurement procedure to monitor concrete performance. Perform measurement procedure at least once per box. A little change in dry cast concrete during production can make a big difference in the appearance and performance of box sections. A wet mix can lead to slumping and excessive cracking along the haunches. A dry mix can lead to voids in the concrete and excessive bugholes. www.concrete-pipe.org

Dry Cast Concrete Box poured with a mix that was too dry and did not consolidate correctly. www.concrete-pipe.org

Vibrated Slump Procedure Tools Cone Height 5.25” www.concrete-pipe.org

Vibrated Slump Procedure Cone Width Weight Width www.concrete-pipe.org

Vibrated Slump Procedure Turn cone upside down and clamp to a vibrating table. Fill cone to the top with concrete. Vibrate for 5 seconds. Do not add the weight yet. Overfill cone with concrete. Mound concrete up around 1” over cone. Place weight on mounded concrete and vibrate for 10 seconds. Strike concrete flat to cone. Turn cone over and remove cone. Vibrate concrete for 10 seconds. Place cone next to vibrated concrete. Measure distance between top of cone and concrete. This measurement is your vibrated slump. www.concrete-pipe.org

Vibrated Slump Procedure Final Slump Measurement www.concrete-pipe.org

Dry Cast Concrete Placement -Placing concrete in your forms correctly is just as important as any other aspect of making a good box. -Pour Dry Cast as evenly as possible. -Placing too much at one time, or mounding, may not allow your vibrators to consolidate the concrete correctly. -Do not turn on vibrators until concrete is at the height of the vibrator. www.concrete-pipe.org

Dry Cast Concrete Placement “Smart Chute” www.concrete-pipe.org

Dry Cast Vibration Are your vibrators actually working for you? Watch amp readouts. Listen for irregularities. Are they rotating in the proper direction? www.concrete-pipe.org

Dry Cast Vibration - Turning on all of the vibrators at once before the form is poured is not necessary. Vibrators move your form, not the concrete. That movement of the form is what is consolidating your concrete. -Sequence your vibrators for a better product and prolong the life of your vibrators at the same time. www.concrete-pipe.org

Dry Cast Vibration Look for a “glossy” look in the concrete along the core and the jacket. Between an inch or two on each side is ideal. If the entire wall has a glossy look to it, your concrete may be too wet or you could have over vibration. If you see your concrete wanting to raise and relax, the vibrators have done all they can do. Just because you can hear your vibrators running, it doesn’t mean they’re working for you! www.concrete-pipe.org

Box Finishing - This is a product that is buried and unseen most of the time. Know the contractors, DOT and your own facilities expectations. A brush and a little water or water reducing admixture often does the trick to seal up the box. Do not let your crew use too much water to make it easy for them to finish. On a box that needs a nice finish to it, try a sponge float with a water reducing admixture sprayed on. www.concrete-pipe.org

Box Finishing Scaling Sponge Float Finish www.concrete-pipe.org

Documentation -The key to making a good box is finding the best system that works for your equipment and sustaining that process. -Always be open to improving that process over time. -Document as much as possible. You don’t know how to repeat something if you don’t know what you did. www.concrete-pipe.org

Documentation www.concrete-pipe.org

Questions? www.concrete-pipe.org