Page 134 - Demo

CONCRETE PIPES AND MANHOLES132 CPI %u2013 Concrete Plant International %u2013 5 | 2025 www.cpi-worldwide.comConcrete and reinforced-concrete pipes can already be used as a source of recycled aggregate. However, a true circular economy requires the use of the highest possible proportion of recycled concrete rubble in pipe production. Therefore, a pilot project with Sika, the Federal Association of Concrete Sewer Systems (FBS) and the R%u00f6ser Group explored whether 100% recycling of concrete rubble was feasible from a production and concrete technology perspective (Fig. 1). The individual steps, from processing the concrete rubble using the reCO2ver process, through preliminary laboratory tests to industrial test production, led to important findings that could significantly revolutionize the concrete circular economy. This article focuses on the problem and the findings gained in laboratory tests.The sewer system is one of the most important elements of our built environment. It is the backbone of our health and contributes significantly to the performance of society. The megatrends of urbanization and environmental protection lead here to major challenges. On the one hand, the sewer system must be durable to reliably fulfill its function. On the other hand, the building materials used must be recyclable to enable possible adaptation to population growth in a resource-saving manner.Challenges of recycling concrete rubbleConcrete and reinforced-concrete pipes are made of mineral construction materials and can be fully reused as recycled aggregates. However, the goal of achieving the highest possible proportion of recycled concrete rubble in pipe production has so far been limited not only by regulatory requirements but also by technological constraints such as the high and variable water absorption and the large and rough surface of the concrete rubble. Both of these factors have a negative impact on the production and quality of concrete pipes in the immediately demoulded production process.Processing with reCO2verWith the reCO2ver process, Sika has developed a processing technology that results in recycled aggregate with an almost primary sand and gravel quality. This process takes place in several steps. In the first step, the old concrete, pre-crushed to a standard but unsieved recycling grain size, is subjected to intense frictional forces in a specially designed ball mill in a continuous process. This leads to the grinding of the cement stone and the cleaning of the surfaces of gravel, grit and sand grains (more details in the reCO2ver video). The %u201ccleaned maNew pipes made of old pipesCircular economy for concrete pipesn Dipl.-Ing. (FH) Jorg M. Schrabback, Specialist Engineer for Pavement Construction (EIPOS), Business Development Manager Concrete Products, Sika Deutschland CH AG & Co KGFig. 1: Circular economy for concrete pipes: New pipes from old pipes%u00a9 R%u00f6ser GmbH/FBS (left and right), Sika AG (middle)