Obersulm rehabilitates city hall square with a special concrete pavement

Obersulm, a municipality in the administrative district of Heilbronn in the German state of Baden-Württemberg, was formed during the 1970s by the merger of six smaller communities. Obersulm belongs to the Heilbronn-Franconia region and to the peripheral zone of the European metropolitan area of Stuttgart. The name Obersulm is derived from the river Sulm that flows through the municipality. The city hall of the community is located in the district of Affalrach, with 4,500 residents, in the collective municipality of Obersulm. For stabilizing the surface of Rohrendorfer Square in front of the city hall, the responsible planners decided on a special block pavement from the Betonwerk Adolf Blatt concrete plant, in the town of Kirchheim am Neckar.

The entire block pavement on Rohrendorfer Square in front of the cityhall had been in very poor condition for many years. Joint gaps a centimeter wide, deep ruts, edges causing tripping hazards on transition areas of the surfacing and at manhole covers as well as loose paving blocks had resulted in the ever less than adequate appearance of this rather prominent place of the municipality. Dagmar Feinauer, of the Obersulm Building Authorities, explains the construction measures: “Although Rohrendorfer Square lies in a traffic-calmed zone, the square of approx. 500 m², with its access roads and paths, is a heavily frequented area with vehicle, bicycle and pedestrian traffic. Damages to the area especially led in the course of years to insufficient surface water drainage. The results were large-scale formation of puddles throughout the entire square. The municipal repair team had to carry out repairs again and again. But the problem was never really solved, because damages kept recurring only a short time after repairs. Isolated replacements were simply insufficient for achieving a uniform, durable surface and functioning drainage. Since the square in front of the city hall in its function represents the community of Obersulm and – moreover, since the square enjoyed increased attention when our community wanted to celebrate its 50th anniversary in 2022 – it was decided to rehabilitate the entire surface course.”

Good experience with Cityblock pavements from Betonwerk Adolf Blatt

After the design proposal had been approved by the municipal council in April 2021, construction work began in November 2021. The community had already had very good experience with Cityblock pavement from Betonwerk Adolf Blatt, in Kirchheim am Neckar, used in the rehabilitation of another street. As a result, this material had also been first choice for Rohrendorfer Square. This is an especially high load-carrying as well as aesthetic surfacing material that, due to its ingenious interlocking system, is also able to sustain higher traffic loads.

Three block sizes were installed: 30 x 30, 30 x 20 and 20 x 20 cm, all 14 cm high. Dagmar Feinauer continues: “A block14 cm thick is highly suitable for resisting heavy traffic loads. Thanks to the interlocking system, static and dynamic loads are to a certain extent distributed across the area.” But yet another reason proved convincing for selecting this paving system: its recessed, molded-on spacers ensured adherence to a joint width of 5 mm at all times. In this way, at least part of the rainwater can infiltrate into the ground, and a suitable substructure will keep the pavement stable.

Great look thanks to twice-crushed and screened chips in the facing

“But the look of the entire pavement was also important,” explains Dagmar Feinauer. “Rohrendorfer Square does have a certain significance for our community. Gray concrete blocks were therefore a no-go. The aim had been to improve the quality of stay of the public space.” For this reason, those responsible chose blocks with a shot-blasted, granite-gray natural-stone facing, laid in a windmill pattern. “That created a very high-quality effect that well matches the surroundings” continues Feinauer. Only little traffic occurs in the peripheral zones of the square, which has been additionally reinforced by large pavers (24 x 16 cm, 10 cm thick), in earthy brown. They feature twice-crushed and screened chipping. Visual separation was achieved with natural stone banding in the form of granite pavers.

The project was completed in May 2022. “We are very satisfied with the pavement,” Dagmar Feinauer sums up.