Concrete monuments must contain which material as per the standards?

Concrete monuments must include ferrous or magnetic material to ensure they are detectable by metal detectors and scanning equipment commonly used in surveying practices. This requirement enhances the reliability of the survey markers, as ferrous materials create a strong magnetic field that makes the monuments easier to locate, particularly in large areas or where visibility is restricted by vegetation or other obstructions.

Including ferrous or magnetic materials is crucial for maintaining the monuments' visibility and usability over time, as surveys often rely on the ability to quickly and accurately locate these points for future reference. Other materials, such as wooden reinforcement, PVC, or plastic additives, do not provide the same level of detection and reliability needed in surveying, and they may not meet the necessary standards for permanence and visibility.