During the development and construction of Nanjing's Southern New City, the old practice of "outbound transportation and landfill" for construction waste has been abandoned. Instead, a new industrial chain of solid waste utilization featuring "green recycling, green production, and green construction" has been created, achieving both environmental and economic benefits. Two production lines can convert 1 million cubic meters of solid waste into construction materials on-site, which are used in municipal projects such as road subgrade and base paving.
With the roar of machines, piles of construction waste are "eaten" into the "red dragon"-like production lines. After vibrating screening, water washing and sorting, uniform crushing, and re-screening, they are processed into qualified granular materials for road construction and other projects. This is a scene witnessed by the reporter (Jin Zhongsi) yesterday at the solid waste utilization processing plant in Nanjing's Southern New City.
The plant is located between the planned Airport No.2 Road and Airport No.3 Road in Nanjing's Southern New City. Since the large-scale demolition and relocation in the new city, a large amount of solid waste has been generated, including foundation concrete and slag from the demolition of buildings.
"According to estimates, the construction waste generated from the demolition in Nanjing's Southern New City totals about 1 million cubic meters. If this construction waste were transported out for landfill, it would not only cost at least 150 yuan per cubic meter, but also occupy a large amount of precious land resources," said Zhao Yuanjun, the EPC project team leader of the Nanjing Southern New City Management Committee. On the other hand, a large amount of filling materials needed for road construction in the area had to be purchased from outside, resulting in incalculable economic and social losses from the back-and-forth transportation.
According to the relevant person in charge of the Nanjing Southern New City Management Committee, the development and construction of Nanjing's Southern New City adheres to the development concept of "innovation, coordination, green, openness, and sharing". In the development and construction processes and links such as planning and design, infrastructure and public supporting facilities, industrial layout, and introduction, it actively explores the concept of low-carbon and ecological development and construction. From the initial conception, R&D and manufacturing to commissioning, the Nanjing Southern New City Management Committee has provided strong guidance and policy support for the construction waste treatment plant, building a good platform for industry-university-research integration and innovative exploration, and strongly promoting the landing and integration of cooperation results with Nanjing University of Technology.
At the initial stage of development and construction, the Nanjing Southern New City Management Committee attached great importance to the treatment and reuse of construction waste within the construction area, strengthened the control of construction waste treatment costs from the system design level, and integrated the relevant technical specifications and management requirements for construction waste treatment and reuse into the EPC project design guidelines. The Municipal Construction Commission took the lead in establishing a construction laboratory, and on the basis of research, demonstration, and testing, first carried out trials in the southern area of the EPC project. An old relocated factory building in Hewan Industrial Park, Qinhuai District was converted into a solid waste utilization processing plant, which processes construction waste for local infrastructure construction. The plant was constructed by China Railway Fourth Bureau and completed in August last year. Currently, it can process 2,000 cubic meters of solid construction waste per day, with a total of nearly 130,000 cubic meters processed so far.
Zhao Yuanjun calculated for the reporter: The 1 million cubic meters of construction waste in Nanjing's Southern New City can produce about 800,000 cubic meters of finished materials, reducing the need to transport 1 million cubic meters of construction waste out of the city and cutting related costs by 140 million yuan. In addition, it can also reduce the purchase of 800,000 cubic meters of lime soil from outside, reducing procurement costs by 96 million yuan. Even after deducting the construction and operation costs of the solid waste processing plant, the total savings still amount to 100 million yuan.
"Construction waste is a century-old resource. Even if it saves costs and protects the environment, it is useless if the road is 'damaged'." To verify the performance of the materials, Nanjing's Southern New City laid a test section of about 100 meters using recycled waste materials on Airport No.3 Road. "The compaction, bearing capacity, and deflection values all exceed the specified values, among which the bearing capacity is 120 MPa, and this test section has reached 200 MPa," said Yi Lexin, the chief engineer of the No.1 Project Department of China Railway Fourth Bureau in Nanjing's Southern New City, with joy.
The reporter learned that the Nanjing Southern New City Management Committee took the lead in cooperating with Southeast University to carry out scientific research on construction waste utilization, referring to relevant domestic and foreign technologies and engineering cases, and compiled the "Construction and Acceptance Guidelines for Construction Waste Used in Subgrade and Lower Parts of Urban Road Engineering in Nanjing Southern New City", which has now passed the review of the expert group. Within Jiangsu Province, this guideline is the first to standardize the large-scale use of construction waste renewable materials. Currently, the project is being organized for promotion. Zhao Yuanjun said that through continuous improvement and improvement, the exploration of construction waste utilization in Nanjing's Southern New City is expected to be widely promoted and applied in the construction industry of the province, achieving good benefits in urban development and construction.
