How Long is The Life of Concrete?

For concrete friends, concrete is a common building material and is widely used. It is also indispensable on construction sites. For example, commercial housing, highway bridges and dams are inseparable from concrete. Although concrete structures have many advantages, their service life is indeed limited. It is affected by many factors, including but not limited to the mix ratio of concrete, construction quality, environmental factors, use conditions and maintenance. The following is a detailed analysis of the life of concrete:

I. What is concrete?

Concrete is referred to as concrete for short. It is a general term for engineering composite materials in which aggregates are bonded into a whole by cementitious materials. It usually refers to cement concrete obtained by mixing cement as cementitious material, sand and stone as aggregates, and water in a certain proportion, also known as ordinary concrete.

II. How many tons is one cubic meter of concrete?

The density of ordinary concrete is 2000-2800Kg/m3, which means that the weight of each cubic meter of concrete is 2-2.8t, but the weight of one cubic meter of concrete is about 2.4t. Different concretes have different specific weights, which are generally not much different.

III. Life of concrete

The life of concrete is generally between 50 and 100 years. Specifically, different types of concrete have different lifespans due to their different quality, composition and use environment. For example:

Ordinary concrete: The general service life is about 50 years, but corresponding strengthening measures should be taken according to different conditions such as earthquakes, climate, and environment.
High-performance concrete: Due to its high strength, durability and other indicators, the service life can reach more than 100 years, but it also needs maintenance.

Portland cement concrete: The service life is 80 years, but under unfavorable conditions such as humidity and temperature, the cement glue stone will expand and crack, and the service life will be shortened.

Prestressed concrete: Because the concrete contains prestressed steel bars, the service life can reach more than 100 years, but the damage of prestressed steel bars will affect the service life.

Alkali aggregate concrete: The service life is similar to that of ordinary concrete, but the expansion of alkali aggregate will cause concrete cracking, which needs to be repaired or replaced according to the actual situation.

Concrete (generally reinforced concrete is used in structures) is a mixture of silicate cement, stone aggregate and steel skeleton. Cement hydration forms a lattice that wraps the aggregate to form a rigid body. This structure is almost the same as natural stone, with extremely strong compressive resistance but cannot withstand tension. The steel skeleton in reinforced concrete has very high tensile strength and can share the tensile and compressive loads with the original concrete. It has good comprehensive performance and is therefore often used in actual projects.

The life of concrete itself can be compared with natural silicate stone. It is well known that the life of mountain rocks in nature is measured in billions of years. Concrete itself can reach this level under good protection, such as specimens in museums or artificial stones inside ancient Egyptian desert pyramids.
However, as long as it is exposed to the environment, weathering in the environment must be considered. Whether it is tree roots, biological growth, or wind, frost, rain, snow, floods, magma, it will have a significant impact on concrete. We also know that rocks in nature will weather into mud and sand, and will be cut and eroded by water flow. Taking these factors into consideration, the life of concrete will not be that long. The life in this case has a lot to do with environmental factors. When the conditions are poor and there is a lack of maintenance, simple concrete will weather significantly within a few decades. And overloaded highway pavement, which is in such bad conditions, may not last for more than a few years.

The third is the life of steel bars. The tensile strength of steel bars is an indispensable part of modern construction, but it is also very easy to be oxidized and corroded in a humid environment. The interior of concrete is initially alkaline, but under the action of carbon dioxide in the air, the pH value of concrete will slowly decrease and become acidic. This process will generate solid calcium carbonate and other substances to increase the strength of the concrete itself, but it is extremely unfavorable for the corrosion resistance of steel bars. If the concrete protective layer is not thick enough, then the steel bars will be corroded and lose their tensile strength when the concrete itself is intact, which will also cause the failure of reinforced concrete components and the collapse of the building. This is the actual structural life of concrete buildings.

IV. The main factors affecting the life of concrete

Mix ratio: The mix ratio of concrete directly affects its strength and durability. Reasonable mix ratio can significantly improve the strength and durability of concrete, thereby extending its service life.

Construction quality: During the pouring and curing of concrete, if the process requirements are not strictly followed, it may cause quality problems such as cracks and hollowing in the concrete, thereby shortening its service life.

Environmental factors: Under environmental conditions such as high temperature, low temperature, humidity, and acid rain, the protective layer of concrete will be destroyed, making the concrete susceptible to oxidation and chemical erosion, thereby accelerating the aging of concrete.

Conditions of use: Concrete is affected by factors such as load, vibration, and impact during use, which may accelerate the aging of concrete and shorten its service life.

Maintenance: Regular inspection, repair and maintenance of concrete structures, including painting waterproof materials and filling cracks, can significantly improve the durability of concrete and extend its service life.

V. Methods to extend the life of concrete

Reasonable design and construction: The design and construction of concrete structures should be reasonable, reduce defects, and ensure the quality of concrete.

Take protective measures: For example, use stainless steel or anti-corrosion coatings to protect concrete structures from external conditions.

Control the environment: Control the environment around the concrete structure, such as avoiding excessively high or low ambient temperatures and excessively high humidity.

Regular maintenance: Regularly inspect and maintain the concrete structure, promptly repair cracks and damage on the concrete surface, and maintain the integrity and beauty of the concrete.

In summary, the life of concrete is a relatively complex issue, which is affected by many factors. In order to extend the life of concrete, it is necessary to comprehensively consider and take measures from multiple aspects such as mix ratio, construction quality, environmental factors, use conditions and maintenance.