Making Large Scale Formliners with VytaFlex® Mold Rubber


THE PROJECT: Few concrete pre-casters would even consider taking on a project this size. The Pennsylvania Department of Transportation needed 2,000 decorative noise reduction panels to maximize public safety and divert highway noise away from surrounding neighborhoods along the soon to be opened State Road #15 in Lancaster, PA.

Each panel measures 10’ x 18’ by 6 “ (3m x 5.5m x 15.25 cm), has moderate stone detail and undercuts and weighs 8,000 lbs./3,630 kgs. By the time the project is finished, over 16 million pounds (7.25 million kilos) of concrete will be cast.
THE PRO: J.R Slaw, Inc. of Bowmanstown, PA is uniquely qualified to take on a project this size with the manpower, equipment and know-how to deliver on time.
THE CHALLENGE: Rising to the Challenge; developing a strategy to cast 2,000 of these panels meant being keenly aware of all the variables necessary to control costs and meet the 1 year delivery deadline. A key to meeting this challenge was Slaw’s development of an innovative ‘post and panel’ system that is superior to other systems and delivers a finished product at a lower cost.
A critical decision to be made affecting the outcome was choosing the right rubber mold material to use for making the production form liners. Slaw determined that 8 formliners used to cast 8 concrete panels everyday, seven days/week would not only meet the deadline, but help them finish the job 1 month ahead of schedule.
ABS plastic that Slaw had used in the past was not an option because it would never reproduce the detail for the stone originals or hold up to the rigors of casting concrete everyday.
After considering alternatives, Smooth-On's Vytaflex® 60 urethane mold rubber was chosen for: 

  1. its ability to perfectly replicate the cobble stone finish from the original model 
  2. abrasion resistance and durability 
  3. flexibility to facilitate demold 
  4. handle the 8,000 lb./3,630 kg. concrete load and retain its shape on a daily basis

After choosing the right mold material, Slaw was onto the next challenge; how to quickly mix and dispense the large amounts of VytaFlex® 60 needed to make the 1,000 lb./454 kg. rubber formliners. Answer: The EZ~Mix® Meter Mix Machine mixed and dispensed 32 lbs./14.5 kgs. of VytaFlex® rubber per minute and each liner took under 1 hour to pour. 24 hours later, the form liners are put into service.
Concrete is cast into each liner daily. Next day, 8 cast sound panels are demolded and loaded onto tractor trailers (4 panels per trailer). They are delivered to the jobsite and taken from the trailer and immediately installed. This “Just In Time” Delivery approach is necessary to minimize cost, increase efficiency and minimize the “installation footprint”. There is no need for a storage area at the jobsite for the precast sound barriers.

Materials Used in this Tutorial

Step 1: Preparing Model and Materials