Asphalt industry experts say it’s difficult to judge which climate is worse on pavement — the warm, wet tropical weather of areas such as Hawaii or the freezing temperatures in regions such as the Midwest.

Different asphalt blends are created to suit each climate, said Jerry Geib of the Minneapolis Department of Transportation’s Office of Road Research. Asphalt pavement is a mix of liquid leftover petroleum, air and crushed gravel and sand.

In a wet but sun-drenched climate such as Hawaii’s, ultraviolet rays tend to age the asphalt ingredient, which serves as the road’s glue, or "binder," said Ricardo Archilla, associate professor of civil and environmental engineering at the University of Hawaii. The asphalt then becomes more brittle, making it easier for water to strip the pavement away. In colder climates the elements work differently. Freezing temperatures cause the asphalt to crack and let water inside the pavement, Archilla said. When that water expands, it "heaves" the pavement up from below.

"It’s a complex issue, but it’s one that people see every day" when swerving to avoid potholes and cracks, said Stephen Muench, associate professor of construction engineering at the University of Washington.

Cities, Muench said, need to think of road construction as just the beginning.

"Very rarely does a road disappear. You build it and it’s there," he said. "If you look at it as a permanent being, you’re more consumed by its upkeep costs."

Hawaii’s asphalt industry — a machine that helps keep the islands’ vehicles moving and economy humming — actually starts in Canada, local industry officials say.

Just about all of the liquid asphalt, the "bottom-of-the-barrel" petroleum that binds the roads here together, is shipped from ports there, including New Brunswick on the mainland’s eastern coast.

After a 7,500-mile journey and a trek through the Panama Canal from New Brunswick, the liquid eventually arrives in Kalaeloa Harbor, at the Asphalt Hawaii plant.

Until recently Asphalt Hawaii controlled about 85 percent of the state’s liquid asphalt market to Tesoro Corp.’s 15 percent. But with Tesoro phasing out production at its Kapolei refinery by the end of April, Asphalt Hawaii will become the islands’ sole supplier of liquid asphalt, industry officials say.

Asphalt Hawaii President Dick Levin said his company can provide the share left behind by Tesoro and that Asphalt Hawaii doesn’t plan to raise prices despite taking hold of the local market. "I’m not particularly demand driven; I’m cost-driven," Levin said this past week. "That’s just how we worked from the very beginning. We’ve been bringing such large amounts that the price stays stable for a long period."

He would not say how much liquid asphalt the company ships to the islands each year. However, about 75,000 tons of the liquid were needed to produce the 1.2 million tons of asphalt pavement laid across the state in 2012.

Three asphalt pavement contractors buy the liquid from Asphalt Hawaii to make the roads laid down on Oahu: Grace Pacific Corp., Road and Highway Builders LLC, and Jas. W. Glover Ltd. Grace Pacific is considered the largest of the three contractors. It has two asphalt-mixing plants on the island, while the other two companies have one each, said Darrell Goo, Grace Pacific senior vice president of operations. With more city repaving contracts going out to bid, Road and Highway Builders intends to invest more equipment, materials and personnel on Oahu, company Vice President Rick Thompson said recently.

Asphalt roads are composed of about 5 percent liquid asphalt, 4 percent air and the rest a mix of crushed rock, gravel and sand. Grace Pacific gets its rock from a Maka­kilo quarry, which it owns, as well as the Ameron Hawaii Kapaa quarry.

Paving and repaving can be a more complicated production than it might appear, Goo said. Asphalt pavement on Oahu generally has to be mixed at 300 degrees Fahrenheit and it must be at least 250 degrees when laid on the road, Goo said. That gives road repavers a window of about an hour to do the repaving work, and it also means the city has to have its traffic plans ready in advance, he added.

"All of that is the underlying thing that people don’t see," Goo said.