Graham Hardwick
Title: Senior Vice President, Aggregate Industries
Age: 53
Experience: 31 years
Graham Hardwick is a mechanical engineer who has always enjoyed the physical feeling of building things that people can touch and see. For Hardwick, who works for Waltham-based Aggregate Industries, those things come in the form of poured concrete, or any other structure in commercial construction that requires sand, gravel, crushed stone or other mined aggregate materials. Most recently, he oversaw the delivery of 30,000 cubic yards of concrete at the 1.1 million-square-foot Vertex Pharmaceuticals buildings under construction in Boston’s emerging Seaport district. The native Australian has been working in the stone side of the construction industry since before he moved to the United States 25 years ago.
Q: You recently coordinated the huge concrete pours that were required for the two Vertex buildings on Fan Pier in Boston, which was the largest construction contract in the country when it was inked. Can you talk about some of the challenges with that project?
A: The biggest challenge with a job of that size is that you have to do a very thick mat, or large volume pours, with about 5,000 cubic yards in one pour. With large placement pours like that with concrete there’s a lot of heat generated. If you don’t do something with all that heat you can get a lot of expansion, which will crack the concrete. A lot of times we use cooling tubes with water running through the pipes like a heat transfer unit to keep the heat out of the concrete.
Q: So that’s how you solved the problem here.
A: Well, no. One of the interesting things we did on the Vertex job was that our technical department designed a concrete mix that was specific for that application that used a high percentage of fly ash, a waste product from coal-fired power plants, that when it hardens it’s just like concrete. That allowed us to replace the cement almost pound for pound with the fly ash. Fly ash has a lower heat generation when it solidifies. So a mix with a high amount of fly-ash meant the contractor didn’t need to run the cooling tubes through the slab. It helps the material dry correctly and eliminates a cost.
Q: That measurement, 30,000 yards, seems like a whole lot of concrete being brought to the site. How do you run the logistics for that?
A: Such large placements [of concrete] require the mix to come from several different plants because of how much concrete they needed per hour. On a lot of jobs, if they’re getting a single pump to a placement, may have 100 or 150 yards every hour. This particular job was up in the order of 400 yards per hour. Logistically, you have multiple points where you have trucks coming and leaving from, and to get trucks to the right place on the job, you have to do a lot of planning beforehand with the contractor. You have to know where all the trucks will queue. There’s not a lot of room to move, so you have to have a place designated for trucks to line up before coming onto the job site.
Q: Why did you decide to move to the U.S. from Sydney?
A: I grew up in Sydney and went to the University of Sydney. I had worked for some Australian companies in the construction materials industry, and one of those had some work in the U.S. I originally came here on a three-year contract, and I guess I was just having so much fun that I decided to stay.
Five Bridge Projects Aggregate Is Bidding On For Concrete Contracts:
- Amesbury/Newburyport. The Whittier Bridge, carrying Route I-95 above the Merrimack River.
- Shrewsbury. Holds Route 9 above Lake Quinsigamond.
- Quincy/Weymouth. The Fore River Bridge, which carries Route 3A over the Fore River Project.
- Fall River. The Fall River Bridge that holds Route 79.
- Boston/Cambridge. The Longfellow Bridge, carrying traffic and the MBTA Red Line over the Charles River along Route 3.
