Mother Nature has reclaimed a former gravel extraction area in Maasvalley Riverpark, a 2,500-hectare nature reserve straddling the Belgium-Netherlands border. To help visitors fully experience the revitalized area, De Gouden Liniaal Architecten designed a small observation tower that blends into the landscape with its rammed earth walls. Built of locally excavated materials, the Observation Tower Negenoord is the first public earthen building in the Benelux region.
The 46-square-meter observation tower is located on a small hill in the heart of the former gravel mine, Negenoord. Although the tower features a sandblasted concrete core, it is clad in external walls built of locally sourced ochre-colored earth, clay, and gravel created with rammed earth building techniques and stabilized with mortar made of volcanic rock. Over time, the external walls will slowly erode away to reveal the gravel aggregate; the gravel content is also visible in the sandblasted concrete core.
“To guarantee the quality of the construction, the design team was supported by an international team of experts: Cratterre/ Vessières&Cie/ BC Studies,” wrote the architects. “The earth-consultants analyzed different local materials, tried different mixes and evaluated them on compression force, abrasion, color and appearance. The chosen mix consisted of 20% gravel, 40% ochre-colored earth, and 40% clay, stabilized with Trasslime. Through its materialization, the building tells us about the location it’s built. and becomes strongly anchored in its environment.”
Roughly triangular in plan, the observation tower features three staircases with landings that offer different views of the landscape. The rammed earth construction took seven weeks to complete, with about 20-meters-cubed of rammed earth finished every week.
Images by Filip Dujardin