【Frontiers in HaiChuan Chemical Technology】Nanda Development’s technology for the value-added recycling of waste concrete through immersion in calcium hydroxide solution has won an award

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Technology for the Value-Added Recycling of Waste Concrete Wins Award 2025-06-06 Recently, a new technology for the value-added recycling of waste concrete developed by Associate Professor Xu Jinjun’s team from Nanjing University of Technology won the gold award at the 50th Geneva International Invention Exhibition. This achievement addresses the issue of high-value recycling of waste concrete in structural engineering, providing support for the green development of the construction industry. 　　The amount of construction waste generated in our country each year is astonishing; in Jiangsu alone, the annual increase amounts to 120 million to 180 million tons. These \"mountains of construction waste\" not only take up land but also pose hidden ecological risks. “The ‘stones’ resulting from the crushing of waste concrete, also known as recycled coarse aggregates, have significant physical defects. ” Xu Jinjun explained that he led his team in developing an integrated device for the automatic washing and screening of recycled aggregates, and proposed a pretreatment process for recycled fine aggregates based on \"immersion in composite calcium hydroxide + curing with carbon dioxide.\" This method first involves soaking the aggregates in a calcium hydroxide solution to enhance their bonding capacity, after which carbon dioxide is added to produce calcium carbonate; this is like putting a strong \"protective armor\" around the aggregates, allowing it to fill their pores. Compared with the single calcium hydroxide soaking method, the apparent density of the recycled aggregates increased by 1.8%~4.8%, while the crushing strength decreased by 20.2%~23.5%. 　　It is reported that this technology has guided the use of recycled concrete in fields such as roads and building construction, in more than 10 projects across various regions in Jiangsu, Zhejiang, and Yunnan.