Recently, Guangdong Redwall New Materials Co., Ltd. (hereinafter referred to as Guangdong Redwall) received a letter of appreciation from China Construction Eighth Engineering Division Corp., Ltd. (CSCEC Eighth Bureau) for its contribution to the Liaocheng-to-Jinan Heat Transfer Project (Yellow River Crossing Tunnel).

During the construction of this major public-welfare project, the technical expert team of Guangdong Redwall rose to the challenge and carried out systematic and rigorous testing throughout the entire process—including concrete mix design, pipeline circulation tests, and on-site casting operations. By applying specially formulated functional concrete admixtures and developing multiple rigorous and efficient technical solutions, the team provided round-the-clock on-site technical support throughout the 19-day production and casting period. As a result, the project successfully achieved ultra-long-distance transportation of C35 self-compacting concrete, including 3 km of belt conveying combined with 750 m of relay pumping, playing a crucial role in ensuring the smooth placement of this special concrete.

It is reported that the Liaocheng-to-Jinan Heat Transfer Project is a domestic ultra-long-distance district heating project designed to introduce surplus heat from the Haoji Power Plant in Liaocheng into Jinan, alleviating the city’s heating supply shortage. The project has a total pipeline length of approximately 40.8 km, and the length of the tunnel through the Yellow River is 4.5 km, with a maximum depth of nearly 60 m, making it the key control section of the entire project.

Faced with the complex underground hydrological and geological conditions beneath the Yellow River, as well as the challenge of ultra-long-distance concrete transportation underground, timely casting of the thermal pipeline concrete foundation became a critical and difficult task. On the one hand, the project schedule was extremely tight; on the other hand, ensuring smooth concrete placement over a distance of 4.5 km posed significant risks, as any pipeline blockage could result in severe consequences.

Based on the project’s characteristics, the CSCEC Eighth Bureau project team adopted a solution in which 3 km of belt conveying was utilized on the east bank using the existing shield-tunneling system, followed by 750 m of relay pumping to complete the casting of C35 self-compacting concrete. There are 2,000 rollers in the 3km belt, and after 2,000 times of strong vibration of ordinary concrete, the aggregate will be seriously sunk or even segregated, which makes it impossible to carry out “long-distance” pumping. Field practice further confirmed that the original concrete mix design failed to meet the stringent “anti-vibration” requirements.

In September 2025, the technical team of Guangdong Redwall was invited to provide on-site technical support and develop an optimized solution. After in-depth discussion and research, the technical team innovatively used a parameter-specific high-frequency vibration platform to simulate the tunnel belt vibration environment and rules. The concrete mix proportions were adjusted based on the technical characteristics of limestone manufactured sand. Using a variety of functional polycarboxylic acid products developed by self-developed monomers, supplemented by special surfactants and polymer water-soluble polymers, through a series of tests to accurately adjust the formula of (functional) high-performance polycarboxylic acid products, and ultimately determine a comprehensive solution for self-compacting concrete that meets the needs of the project. Based on the experimental results, belt anti-vibration verification tests and a 750-m pipeline circulation test were conducted, with performance exceeding expectations.

From October 27, over a period of 19 consecutive days, the technical team of Guangdong Redwall provided 24-hour on-site support to ensure the successful placement of nearly 16,000 m³ of self-compacting concrete. From laboratory testing to pumping operations and final placement, the professional product technology, efficient after-sales service, and meticulous work ethic of Guangdong Redwall were highly praised by the CSCEC Eighth Bureau project team, who expressed their appreciation through a formal letter of thanks.