This story was originally published in Concrete Construction.
The fog surrounding “100-year service life” won’t clear for some time. But when it does, says durability expert Jacques Marchand, something brand new will emerge: a whole new engineering discipline specializing in durability.
A few weeks ago, we heard from a Kiewit engineer about the challenges of delivering on service-life requirements where no codes or consensus definitions exist in North America – a sketchy proposition to say the least. In today’s interview with Infrastructure Imperative’s dean of “Designing and Building Resilient and Durable Infrastructure,” we catch another glimpse of what the priorities must be now ... and what the promise for durability is in the future.
Jacques is co-founder of Canadian engineering firm SIMCO Technologies and an internationally recognized expert in mix design, degradation mechanism analysis, and durability modeling of concrete infrastructure. Professionals who are involved in infrastructure of any kind must come to the table and fully comprehend the pulse and progress of the durability debate – and the most efficient way to get up to speed will be hearing the perspectives of Jacques and his co-presenters Nov. 13-15 in Cleveland. Make your reservation at http://www.infrastructureimperative.com/. What Jacques has to say here is just the tip of a crucial industry iceberg.
Concrete Construction (CC): Can you explain, at a high level, what’s going on with regard to durability?
Jacques: At the beginning of my career (many years ago), nobody was concerned with or talking about infrastructure “durability.” Structures were designed to safely carry loads and calculations used fresh building materials in pristine condition. The assumption was that degraded structures would be replaced.
We’re beginning a totally new period because we’ve realized we can’t possibly replace everything built over the past decades. Some structures will have to be repaired. So we might as well design new construction not only to be safe, but also to be durable.
Today, owners are increasingly introducing new requirements pertaining to durability. It depends on the owner, but they want structures to be designed from 75 years to 100 years and, in some cases, to 120 years.
CC: And the problem with that is...?
Jacques: Owners define service life and durability in different ways. Sometimes the owner says “I want to have 100 years” without precisely telling you what it means in reality and what they're shooting for. In other cases, you get very detailed specs.
It varies quite a bit from one project to another and is highly dependent on the technical level of the owner and owner’s representatives. It’s the owner who’s setting the tone for all of this.
Here in North America, we have to better define the vocabulary we're using. Define expectations; make sure we come up with codes and standards that are in line with these new durability requirements.
CC: What’s being done to address the confusion?
Jacques: Technical associations like the American Concrete Institute are increasingly aware of this problem and creating groups to develop new codes and standards.
Bottom line: We're slowly migrating from a period of not being concerned about these issues to something more rigorous. For those who have to design and build structures, that evolution is a challenge.
On the positive side, we do have cases where owners are using more structured approaches and implementing rules and requirements that are much better defined.
We are going in the right direction.
CC: As you’ve alluded, roads and other infrastructure can’t just be replaced every 25 years. What are the opportunities for ensuring resilience with an existing asset?
Jacques: We've learned that if you really want to extend useful life, you must first have a lot of information on current condition: what problems are affecting the structure and the extent of those problems. If you skip that step, you won't have any beneficial impact on service life extension. And that’s a waste of time and money.
Do a full condition assessment to identify the problems affecting materials and then design the repair.
CC: What are some of the underlying owner objectives for these repair scenarios?
Jacques: Sometimes they say, “We know we'll have to replace this structure in 10 years because it will be obsolete, so we only need to buy 10 years.” In other cases, owners are telling us, “We need to buy at least 50 years.”
We need to identify the problems and the extent of each, and then design for one given objective.
CC: What’s the big reveal you’ll share at the Infrastructure Imperative?
Jacques: We now know enough to design for durability. True, we don't have rules and everything is a little fuzzy; but we’re developing a new discipline called durability engineering. It's based on the premise that over the decades we've generated enough knowledge on what affects useful life of various structures. It's a combination of the environment in which they’re built, materials, and design. And at some point, we're going to have new codes and standards.
We'll reach a point where you'll have a structural engineer designing for safety and a durability engineer designing for a given service life for new construction and existing structures.
CC: Put on your “wizard’s hat” for a moment and imagine you could make one universal decree. What would you would cause to happen for every new project that would enhance durability everywhere in the world?
Jacques: To clearly define expectations during the planning phase. Once that’s done, a lot of problems will be automatically solved because you can come up with solutions.
The most confusing element at the moment is when we're talking about 100 years. That means one thing for some owners and for others it means something totally different – typically within the same organization!
The conference will be a good opportunity to talk about this.
We're trying to answer questions that aren’t precisely defined. That sounds esoteric, but it's not. It triggers lot of other major problems. If we spent much more time at the initial stage by clearly defining and then translating expectations into real technical requirements, the lives of the people who design and build infrastructure would be much easier. And owners would be happier.
If I had a magic wand, that would be my first act.
Note to our esteemed readers: Please make your first act today a click to register for Infrastructure Imperative, where the durability saga will continue along with rousing developments revealed in the areas of streamlining projects and improving construction efficiency. LET’S WIPE OFF THE INFRASTRUCTURE D+ FROM OUR COLLECTIVE REPUTATIONS. DO NOT MISS THIS TIMELY OPPORTUNITY TO BE AN ACTIVE PROBLEM-SOLVER FOR YOUR COMMUNITY AND THE NATION.
This story was originally published in Concrete Construction.