Concrete Uses in Runways and Taxiways
Air transportation has been an influential part of people’s lives for the past 100 years.
People fly from one destination to another and rarely think about the runways or taxiways that are being used. They fail to think about the extreme loads that cargo and passenger planes endure when they are just sitting at the terminal. Runways must be able to withstand massive loads of several hundred tons on take-off and especially on landings. There have been several different types of runways used throughout the history of flight and many are still used today. In the beginning, there was nothing fancy about landing areas; airplanes landed in grassy fields (some are still used today). However, it becomes increasingly difficult to manage these types of landing strips with constant changes in weather. More recent runways are manufactured from concrete and asphalt. Some are smooth and some are hatched perpendicular to the runway to improve stopping time and distance. The uses of concrete are so vast that it is impossible to take into consideration all of them in this specific project. Not only does the use of concrete take in a broad range of applications, it is also constantly changing through improvements in the strength and durability of the materials involved.
The Colnbrook Plant, which opened in 2002 and is managed by London Concrete, has two 11m3 tilting drums that can produce concrete at a rate of up to 600m3/h and is believed to be the largest capacity plant in Europe.
London Concrete is in the process of supplying concrete for the repair of runways and taxiways. The concrete being manufactured and supplied has a mix design capable of achieving 20MPa at four hours. This allows repairs to be carried out during the nighttime hours and able to be used before the peak air traffic hours the next day. This allows for average usage (roughly 400 tons) at only four hours old.
The concrete is delivered with a slump of between 25mm and 100 mm dependent on site application, and allows for excellent compaction. The initial set of the new type of concrete is at one-half hour, and there is still sufficient time to apply a finish. The compressive strengths of this concrete have been tested at twenty-eight days with a maximum of 90Mpa.
The Pavement and Infrastructure Team, which consists of AMCE and TPS, has a long-term partnership agreement sharing the objective of continuing improvements to the performance of and providing added value to the concrete being used. Being that pavement-quality concrete is the main product used in the reconstruction of significant areas of airfield pavement, it was the prime target for improvement.