With concrete runway reconstruction projects on both airports in Kansas City, Loch Sand & Construction Company is using its experience and innovations to provide a quality product that meets the stringent strength and smoothness requirements of the Federal Aviation Administration (FAA).

The Maryville, Mo.-based contractor has completed various projects at Kansas City International Airport going back to 1995 and is currently constructing extensions to Taxiways B and D. The $9-million project includes approximately 30,000 square yards of 15-inch concrete and all new electrical, lighting and signs. The crew began its work in late-March and will complete the work in November.

At Charles B. Wheeler Downtown Airport, Loch is reconstructing the 8,500-foot 1–19 Runway. The $19-million project also includes longitudinal edge drains and all new lighting. This season, Loch's crews and subcontractors will complete approximately 60 percent of the project to have the runway open by late October. In the spring, they will tear out the last 40 percent and complete the reconstruction by July.

On both projects, Loch is using an in-house concrete mix designed by its Chief Engineer Ron Tavernaro.

"We developed the mix to meet the FAA requirements for flexural strength," said Tavernaro. "They have a PWL (percentage within limits) calculation and if your standard deviation varies too greatly there is a deduct on your performance."

The concrete mix, Tavernaro said, is crushed rock, Missouri River sand, Type F fly ash, and cement. In addition to meeting the FAA's flexural strength requirements, the mix arrests or mitigates Alkali Silica Reaction (ASR), which can cause cracking.

"We spent two months working on different mix designs needed to alleviate ASR," said Loch Sand & Construction Treasurer and Equipment Manager Rob Loch. "We looked at using Type F fly ash on one of the projects and blast furnace slag on the other but Ash Grove gave us their commitment that they could get us the Type F and they have done a good job of supplying both projects from Texas."

In addition to the Type F fly ash, Ash Grove is also supplying cement for the Downtown Airport project from its Chanute Plant, while Lafarge is supplying cement for the KCI project from its Sugar Creek Plant.

"This is our first experience using Type F but it has made for a really good mix," said Loch. "It is workable and the strength has been outstanding."

"I think it's one of the best mixes we've ever used," said Jerry Wilson, Loch's vice president of operations and project manager on the Downtown Airport job, where the crew is paving 14 inches deep on 10 inches of Type 5 rock and 6 inches of asphalt drainable base.

To help maintain the workability of the concrete through some hot weather, Loch's crew at the Downtown Airport sprayed the asphalt base with a water-based white curing compound to dissipate the heat and act as a bond breaker. "The 'black' was absorbing the heat," Tavernaro said. "Jerry got a change order for the 'white' and it changed the temperature 25 degrees. That allowed us to improve the pavement quality."

"I don't know that it would have given us problems but it provided a better product because we didn't have to pour our concrete in a frying pan," said Wilson. "We pour a very rich mix so the set time is maybe 20 minutes behind the paver. To slow that down, we run a chiller, but cooling the base temperature made it easier to handle because we didn't have a flash set as soon as it came out of the truck."

Loch mixed the concrete for the Downtown Airport project on-site in its RexCon 12-yard plant in 10-yard batches hauled by dump trucks. For the 8,000-foot by 150-foot runway, the crew paved 25 feet wide with a Gomaco GP 3000 four-track paver. The concrete was placed with a Gomaco PS 2600 spreader and a Gomaco TC 600 cure and texture rig followed the paver.

"Our results have been excellent," Wilson said. "We have a blanking band smoothness requirement with our measurements in a 7-inches-per-mile spec and we have been 1-inch to zero, earning 100 percent of bonus for everything we've paved this year."

The results have also been good at Kansas City International Airport, where the paving is more complicated at best.

"It's not 'pave and go' out here," said Gary Kirtley, Loch project manager at KCI. "We have a lot of odd shapes, radiuses, tapers, and short pulls because we're trying to match existing lanes."

At KCI, the crew is paving 15 inches thick on a base of 9 inches of lime, 6 inches of P209 rock and 11 inches of Econocrete. "Essentially, we're paving the job twice," Kirtley noted, "first with Econocrete and then with concrete. Our paving widths are 25 feet, 20 feet and 18 feet 9 inches and we have some pours from about 75 feet to a couple of thousand feet."

In addition to the 15-inch paving, the crew is also paving a road to the airport's new fire and rescue building and paving the intersection of the Bravo and Mike runways. Loch is using its Con-e-co All-Pro 12-yard plant at KCI and is handling the paving challenges with a Gomaco GP 2800 two-track paver, Gomaco PS 60 and 9500 placer/spreaders and a TC 400 texture/cure machine. "Using the two-track machine gives us the flexibility we need to handle the longer pulls as well as the tapers and other smaller things," Kirtley said.

"We are profilographing everything and we've had really good readings on the longer pulls," said Kirtley. "Our thickness and strength have also been outstanding and we've been very close on our standard deviation. We have earned 106 percent of bonus so it's going well."

According to Loch, it has been an advantage for the company to have both jobs going on at once. "We were low on the Downtown Airport bid first, then the KCI project," Loch said. "That allowed us to handle both jobs out of our Kansas City office and to utilize some equipment and personnel on both jobs as needed. It's also an advantage that the same project engineer, Laponzia Jones, is handling both projects for the aviation department. We have worked with her on several projects and we have a good relationship because we know what to expect from each other.

"It also helps that we have two good design firms, TranSystems at the Downtown Airport and HNTB at KCI. They have ideas on how to improve the process or do the work more efficiently and, after that, it's a matter of achieving quality. We do that with good leadership, good people, good materials, and good equipment. It takes a lot of parts to make it work right but we have the good people and subs and suppliers we need."