Berntsen offers the following styles of aluminum concrete survey markers for use in concrete or rock:
"C" style (US Army Corps of Engineers Type 1 Disc) has the classic 3" (76mm) long split-style tapered stem. It is available in 3-1/2" (89mm) or 4" (102mm) diameters. Orbital formed from solid 6000 series aluminum bar.
For smaller marks use the "CD" style 2" (50mm) diameter marker has a 3 /4" (19mm) diameter x 2" (50mm) long stem and is notched to hold firmly in concrete or rock. Orbital formed from solid 6000 series aluminum bar. It is also available as a leveling mark with a raised datum point (with recessed center) for precise monitoring (model CD2L).
The "RT" style is a variation on the concrete disc theme and is available in a 3-1/2" (89mm) diameter. The RT1 offers more resistance to twisting and features four legs. Orbital formed from solid 6000 series aluminum bar.
Our aluminum material is versatile and resistant to most environment conditions, however, if the survey markers are intended to be used in high traffic or caustic environments, such as roadways or salty conditions, we highly recommend using bronze survey markers to improve the lifetime of the markers.
The CAPMAG ceramic magnet can be used with concrete markers to assure easy detection of the mark by a magnetic locator. Dimensions are 1/2" (13 mm) in diameter & 1/4" (6 mm) long. The magnet can be located up to 6 to 12 inches deep with a magnetic locator, depending on soil conditions.
RT35D Concrete Marker Installation Instructions