Ten years after NRMCA introduced its Prescription to Performance Initiative (P2P), the concrete industry continues to fine-tune how the program can enhance the relationship between producers and other members of the construction community, all in the name of developing better projects.
Unlike other programs where there is a clearly defined road map for implementation, there are lots of gray areas with P2P. It means different things to many people, and there are different ways to make it a reality. Another difficulty in measuring its success is a lack of projects to which the concrete industry can point as evidence of the initiative's success.
“The problem is, how do you quantify a performance project, and is it a result of the P2P initiative?” asks Colin Lobo, senior vice president of engineering at NRMCA. “We've tried to collect case studies to document and have not been very successful. There has been progress from the sense that we've made a few changes, but whether that has translated into performance projects, I can't even tell.”
If there is one, the I-35W St. Anthony Falls Bridge in Minneapolis would qualify. “There was a lot more freedom given to the contractors and producers to deliver the options, as opposed to a Mn/DOT (Minnesota Department of Transportation) type of specification.” Lobo says. The bridge opened in 2008, one year after the original span collapsed and killed 13 people and injured 145 others.
Kevin MacDonald, vice president, engineering services, with Cemstone, the Mendota Heights, Minn.-based producer which supplied 50,000 yards of concrete to the project, agrees the bridge meets P2P's parameters. “It was performance-based, in that we were given certain physical requirements for the concrete, and it had to have a certain strength, or certain shrinkage result,” MacDonald says. “The contractor did not care how we got there.” While Cemstone reported mixture proportions because of the scrutiny the project was under, “there were no significant limitations,” put on the producer, MacDonald says.
“We're going through an evolution, like with all really great ideas,” adds Chris Wolf, director of technical services with Shelby Materials, a producer based in Shelbyville, Ind., with eight plants. “It doesn't just pop out of the oven, ready to eat. It has to be morphed or go through an evolution. It's such a culture change. The concept of P2P is having trouble defining itself.”
P2P's origins trace back to October 2002, when NRMCA's Research, Engineering, and Standards Committee formed the P2P Steering Committee to develop a roadmap for the initiative. The goal was to move away from prescriptive job and material requirements to those based on performance specifications.
P2P shifts prescribing the ingredients and their proportions in a concrete mix to an emphasis on performance properties of the combined materials, according to NRMCA. Compared to other participants on a job, including the owner, architect, designer, and general contractor, the concrete producer is the ultimate expert on optimizing a mix, both in its plastic and hardened state.
The association realized this initiative could not succeed in a vacuum. Producers needed buy-in and cooperation from other members of the construction team. “The P2P initiative is a large undertaking with far-reaching implications throughout the construction industry that will require coordination with, and support from, project owners, government agencies, codes and standards organizations, engineers and architects, contractors, and concrete producers.” the steering committee stated. “Eventually, it should be considered an industry initiative, rather than that of one group.”
People have different perceptions and opinions of what a performance-based project is. Lobo recalls the Florida DOT wanted to be involved in such a pilot project. “They said we'll give you all of the freedom, but you have to use this much cement and this much of this and that,” he says. “It's very hard for them to change their regulations without considerable effort.” In another case, the Washington State DOT developed what it said was a performance-based specification, but everything in it was prescriptive.
So what would be the ideal performance specification? If an owner said, “Give me a structure that meets my functional requirements for 75 years, that would be the ideal performance spec,” Lobo says. But that would be for everyone on the construction team, not just the concrete producer. The designer and contractor would also have to buy in.
There is agreement on what a performance specification is not. “If a producer says, I'm going to use my secret mix and not tell anybody, that is the wrong direction,” Wolf says. “Saying, I'm not going to tell anyone about my concrete. I'm just going to deliver it, the specification community is not going to live with that.”