Welcome to the Freedom Center Exhibit of the Berlin Wall!
As this is an Earthcache, there is no physical container. Answer the quesitons below to log this cache!
In 2010, the National Underground Railroad Freedom Center in Cincinnati received this artifact: a 4-by-12-foot, three-ton section of the Berlin Wall. This segment was a gift from the city of Berlin to Cincinnati.
The wall section is displayed outdoors on the south side of the Freedom Center, between the museum and the Ohio River. The side facing the museum, originally oriented toward West Berlin, is adorned with vibrant graffiti, including the depiction of a woman’s face. To preserve this historical artwork, the painted side is now protected by glass.
Conversely, the side facing the Ohio River, which once faced East Berlin, remains stark and unadorned. During the wall’s existence, the East German government painted this side white and implemented strict security measures, including ditches and barbed wire, to deter escape attempts. The white paint served to highlight individuals attempting to flee, making them more visible to guards.
This EarthCache focuses on how environmental factors have impacted the Berlin Wall segment.
Concrete Erosion & Weathering
The Berlin Wall segment at the National Underground Railroad Freedom Center has been exposed to Ohio’s climate since its installation in 2010, and many years before in Germany. Environmental factors such as freeze-thaw cycles, acid rain, and air pollution have played a significant role in the wall’s ongoing weathering. In Ohio’s winter climate, water can seep into cracks in the concrete, freeze, and expand, leading to the formation of new fractures and widening existing ones. Acid rain and urban pollutants can also react with the cement matrix, breaking down the outer layer and exposing the aggregate beneath the surface. As you examine the wall, look for signs of these weathering effects, such as surface pitting, spalling (flaking), and rust stains from corroding steel reinforcement.
Concrete Description
Concrete is a composite material made from cement, water, and aggregates (such as sand, gravel, or crushed stone). In the case of the Berlin Wall, the concrete was reinforced with steel rebar for added strength—a common practice for Cold War-era defensive structures. The steel reinforcement improves tensile strength but also makes the concrete vulnerable to corrosion. When moisture penetrates the concrete, it can cause the steel to rust and expand, leading to cracks and weakening the structure over time. The graffiti side of the wall, once exposed to the public in West Berlin, shows evidence of environmental stress, while the white-painted side that faced East Berlin remains more stark and weathered.
History Lesson: Cold War-Era Reinforced Concrete
The Berlin Wall was constructed in 1961 using reinforced concrete designed for durability and strength. The combination of concrete and steel reinforcement made it resistant to physical impact and difficult to breach. However, over time, environmental exposure and pollution have taken their toll. The segment in Cincinnati retains these features, with visible signs of wear that reflect both the original construction techniques and the effects of aging in an urban Midwestern environment.
During the Cold War, concrete used in the Berlin Wall typically included:
- Portland cement – The primary binder in the concrete.
- Steel reinforcement – Rebar or wire mesh embedded in the concrete for tensile strength.
- Heavy aggregate – A mix of natural and crushed stone.
- Additives – Chemicals to enhance workability and resistance to freezing or cracking.
The segment in Cincinnati reflects this Cold War construction, with signs of exposed aggregate and rust staining where the steel reinforcement has begun to corrode due to moisture exposure.
Key Factors of Cold War Concrete:
• Portland cement: The primary binder in the concrete.
• Steel reinforcement: Typically, rebar or mesh was used to provide structural integrity.
• Heavy aggregate: Often a mix of natural and crushed stone.
• Additives: Chemicals to improve workability, setting time, or resistance to freezing or cracking.
These materials allowed for long-lasting defensive structures, though over time, erosion of the surface and corrosion of the internal steel are common issues.
LOGGING REQUIREMENTS
Please complete the tasks and questions below, and send me your answers. If logging for a group, please include the names of everyone in your group.
1) Compare the concrete on both sides of the wall. How does the side protected by glass (originally facing West Berlin) differ in texture, color, and condition from the exposed side (originally facing East Berlin)? How do you think Ohio’s climate and the protective glass have influenced these differences?
2) Compare the wall’s condition to other exposed concrete you’ve seen, such as a sidewalk or buildings. How might rain, freezing temperatures, and pollutants have affected the Berlin Wall differently?
3) Based on the materials used in Cold War-era concrete (cement, steel reinforcement, and aggregate), how do you think the presence of steel impacts the type and rate of erosion?
4) Take a photo of yourself (or a personal item) with the Berlin Wall segment or anything interesting about the site. You can attach it to your log (optional).
This EarthCache provides a blend of historical context and geological observation, teaching participants about weathering and the enduring legacy of historical monuments.