Concrete durability is concrete resistance to environmental media, long-term maintenance of good performance and appearance integrity, so as to maintain the safety of concrete structure, normal use of the ability. Its quality directly determines the life of concrete engineering, so it has been highly valued by the industry for a long time.

To improve the durability of concrete involves design, materials and construction technology and other aspects, not only need to pay attention to the density of concrete and strength selection, cement composition, process selection, etc., but also need to establish a thinking mode from the perspective of the whole industrial chain.

This newspaper set up a column "Focusing on Concrete durability", aiming to start from how to improve the durability of concrete in different environments, through the interviews with concrete durability experts in different fields, reflect the current situation of the industry, focus on the industry problems, show the technical progress of the industry, and provide reference for the further improvement of concrete durability.

As the material foundation of construction industry, the durability of concrete material determines the service life of concrete structure. Therefore, in the "double carbon" road, how to improve the durability of concrete, prolong the service life of buildings, has become a common concern of the whole concrete industry.

"To ensure the long life of the building, the concrete material needs to be adapted to the environment." Recently, in an interview with our reporter, MCC building research institute of concrete material chief expert, national industrial building diagnosis and transformation engineering technology research center deputy director Hao Ting Yu proposed, for concrete, general indoor environment deterioration factors are less, to prevent the steel corrosion caused by carbonization is given priority to; However, concrete structures in industrial buildings are faced with many unfavorable factors such as high temperature, heavy load, fatigue and corrosion, so the deterioration of concrete durability is significantly faster than that of civil buildings. In addition, there are also different deterioration factors such as structures directly exposed to the natural environment, coastal buildings, "de-icing salt" sprinkled in winter, and saline-alkali problems in soil and water bodies. These diverse environments need to be dealt with separately, so as to put forward the corresponding durability index system.

Hao Tingyu said that the improvement of concrete durability needs to be controlled from the whole process, that is, from raw materials, design, construction, testing, operation and maintenance and other links. Ready-mixed concrete is delivered as a semi-finished product, while the user uses hardened concrete. From the semi-finished product to the concrete structure, the concrete material needs "careful care" to serve the structure well during its life cycle.

"Problems at any one point can have an impact on the durability of concrete." Hao Tingyu believes that at present, people's "concrete maintenance" concept is not in-depth, in fact, no matter from the design, construction, or maintenance, testing, each link people should realize its importance, only from the perspective of the whole chain to do a good job of concrete durability, to protect our buildings.

In addition to the impact of environment, construction, inspection, maintenance and other factors on the durability of concrete, the raw material factors of concrete manufacturing should not be ignored.

In this regard, Hao Tingyu proposed that about 70% of the volume of concrete is sand and stone aggregate, which constitutes the skeleton of concrete materials. In order to improve the life of concrete from the perspective of sand and stone aggregate, it is necessary to improve the industrialization level of sand and stone products manufacturing and the information level in the application. Secondly, admixture is also very important to improve the durability of concrete. "At present, the traditional admixture based on fly ash and slag is increasingly in short supply, and the composition is more and more complex, and there are even fake fly ash into the market in many places. In this case, to ensure the quality of the admixture and find alternative materials becomes an urgent problem." "Hao Tingyu said.

Hao Tingyu has been engaged in the research of civil engineering materials and concrete structure durability for a long time. When talking about his work, he said that the diagnosis and treatment of concrete diseases and the research and development of new green and low-carbon concrete technology oriented by engineering demand are the main work of his team. Among them, the diagnosis and treatment of concrete diseases includes the analysis of the durability of various structural concrete diseases and the design of repair and protection schemes. In this regard, the team has completed the disease diagnosis and treatment of more than 40 large public buildings, Bridges, tunnels, industrial and civil buildings, etc., contributing to the long-term safe service of these important concrete structures. The research and development of new green and low-carbon concrete technology oriented by engineering demand includes the preparation of green high-performance concrete from local materials to meet the different needs of metallurgical workshop, bridge and tunnel construction, and far-sea construction, which provides material guarantee for the smooth progress of the project.

After 22 years of working as a "concrete doctor" since he entered the concrete industry in 2000, Hao Tingyu has become emotionally attached to the industry. Talking about the future, he pointed out that his team will continue to strengthen the field inspection and monitoring technology research of concrete structure durability, as well as the technical research of the safe use of solid waste in concrete materials. As for how to promote the durability of concrete, he suggested that the first is from the legal level, should vigorously advocate the centennial building. Not only important buildings and Bridges are required to have a life span of 100 years, but also ordinary residential buildings should break through the existing property rights restrictions and improve the service life of the existing design. Second, in the technical level, strengthen the whole chain control. That is to improve the understanding of concrete durability from raw materials, design, construction, testing, operation and maintenance and other links, and implement in engineering practice; Thirdly, at the standard level, the carbon emission and calculation boundary of the concrete industry are not unified at present. It is necessary to discuss and clarify the boundary around its whole life cycle, and quantitatively calculate the contribution of durability improvement to carbon reduction.