New U.S. Army Engineer Research and Development Center (ERDC) research has revealed a surprising link between face bricks and the often urgent need for low-cost road and airfield infrastructure in theater environments. Differing from brick pavers, which are used for roads and sidewalks, face bricks are less expensive and are typically seen in cosmetic applications on houses and buildings. However, recent tests showed they have an application possibility as an alternative to asphalt paving for roads.
“Face bricks were not intended to be used in paving applications, since their properties are mostly meant to resist freeze/thaw, whereas a true paving brick is meant to resist freeze/thaw as well as abrasion and slip/skid resistance,” said project manager Haley Bell, an ERDC research engineer. “It was suggested that we try using the face bricks because resources for construction of infrastructure, particularly roads and airfields, are limited in the Middle East, where we are currently at war.”
The need to overcome the handicap issued by those limited resources prompted the Air Force Civil Engineer Center to fund the project, which specifically looked at contingency environments in locations where money, not to mention material and equipment, is a rare commodity. Face bricks could be recycled from buildings set to be demolished, in addition to those available for purchase, and could be placed quickly and with ease. But would they hold up?
“We started the project with a literature review to identify various types of bricks, compositions, manufacturing process, strength characteristics, previous uses in roads and floors, specifications and common laboratory testing,” said Bell. “We then began a laboratory study using five types of face bricks, evaluating strength and durability. We also included a brick paver as a control for the study.”
The results were good. Out of the types of face bricks tested – two types of standard modular house bricks, old brick, commercial building brick and wood-molded brick – several displayed characteristics equal to or stronger than the brick pavers. A following full-scale evaluation of the bricks also produced positive results, showing face bricks tested under controlled environmental conditions are capable of withstanding low-volume truck loads of approximately 54,000 pounds.
“Each brick type was trafficked to 10,000 passes and measured less than 1-inch of surface rutting; failure of asphalt pavements subjected to truck traffic is defined as 3-inches or more of surface rutting,” said Bell. “The bricks were not capable of withstanding fully-loaded C-17 traffic, which is 585,000 pounds or 42,000 pounds for a single-wheel load, and all failed at around 35 passes. Failure of flexible airfield pavements subjected to aircraft traffic is 1-inch of surface rutting.”
Because the original was conducted in an environmentally-controlled hangar, ERDC researchers recommended an additional full-scale test using truck traffic with various periods of known precipitation. In particular, they want to look at issues that may be caused by freezing and thawing periods, as well as the high water absorption percentage of the bricks, which could indicate a longer drying time following rain. They also recommended evaluating brick roads for grouser, or turning, effects of track vehicles, evaluating crushed bricks for use as a base course material for roads and evaluating crushed bricks as aggregate for use in asphalt or concrete mixtures.
With continued efforts, a solution may be near for future contingency operations.