Causes of Concrete Cracking and Prevention Measures

Concrete structures can effectively enhance the stability and compressive strength of buildings, as well as increase the load-bearing capacity of roads. Therefore, the quality of concrete construction directly relates to the overall quality of the project. However, in recent years, the incidence of concrete quality issues in our country has been increasing, directly affecting the safety of people's travel and their lives and property, thereby causing a negative impact on social stability. This article explores the causes of concrete cracking and prevention measures.

Currently, concrete cracking issues in our country can be classified into three types: surface cracks, through cracks, and deep cracks. Each type has different characteristics and impacts.

Surface cracks are relatively narrow and do not affect the performance of the construction project; however, they can impact the appearance of the building.

Through cracks and deep cracks are wider and tend to increase over time, which can directly affect the internal structure of the entire project. This, in turn, impacts the stability and compressive strength of the building, potentially reducing its service life and, in severe cases, threatening the safety of people's lives and property.

1. Materials Do Not Meet Quality Standards
Concrete is made from a combination of various materials, including cement, so the quality of these materials directly affects the quality of the concrete. However, many construction units prioritize immediate economic benefits and fail to choose materials that meet national quality inspection standards during procurement, which compromises the overall quality of the concrete.

2. Excessive Load Causes Cracking
Reinforced concrete structures have their own load-bearing capacity. When the load exceeds this capacity, it can affect the stability of the structure. Many construction units in our country do not effectively consider and design for this aspect during the planning phase, leading to excessive load pressure on reinforced concrete structures over time, resulting in cracking issues.

3. Poor Corrosion Resistance of Reinforcement
The steel reinforcement used in reinforced concrete structures in our country has some inherent corrosion resistance. However, after a period of use, moisture and air can cause corrosion of the reinforcement. If suitable admixtures are not selected based on the actual conditions at the construction site, this can exacerbate the corrosion of the steel. As corrosion worsens and the volume expands, it can directly crack the concrete cover, leading to a decline in the overall structural performance of the building.

4. High Temperatures Cause Cracking
One significant factor contributing to surface cracking in cement concrete is the heat of hydration of the cement, which can lead to cracking in large volumes of concrete.

5. Foundation Settlement and Deformation Cause Cracking
One of the primary causes of cracking in high-rise concrete structures is uneven settlement of the foundation. When there are uneven settlement phenomena affecting the foundation and upper structure, it can lead to cracking. These cracks tend to increase in size from the bottom upward and may appear in an inverted "V" shape.

6. Issues with Construction Quality
Concrete construction is a highly specialized and challenging task, requiring significant technical skills from the workers. It is essential for construction personnel to strictly adhere to relevant technical requirements and construction processes to ensure the quality of the concrete work. However, in practice, many construction units lack professional concrete construction technicians. In their rush to meet deadlines and pursue economic benefits, many construction units fail to regulate the behavior of construction personnel properly. Some workers lack the necessary expertise and do not adequately prioritize construction quality, leading to significant issues and resulting in concrete work that does not meet quality standards.

1. Effectively Control Material Proportions
Mastering the correct material proportions is fundamental to ensuring the quality of concrete construction. Therefore, construction units must place greater emphasis on this aspect. Technical personnel should adjust the concrete mix according to the actual conditions on-site while adhering to the principle of minimizing the unit water content and following the design criteria of "three lows, two admixtures, and one high." This approach ensures that the quality and performance of the concrete meet relevant national standards. It is important for construction units to uphold the principle of quality first when procuring concrete materials, selecting high-quality, high-performance materials that meet construction design requirements, and establishing long-term, effective relationships with suppliers to reduce material costs. When determining material proportions, technical personnel should continuously adjust the mix based on the actual site conditions to meet current construction requirements. The amount of cement should be determined based on factors such as heat of hydration and bleeding. Additionally, water usage for concrete must be strictly controlled to ensure the viscosity of the cement paste, reduce aggregate settling, and optimize the role of sand and gravel. During summer construction, it is crucial to effectively control the temperature of the raw materials, especially the temperature of the cement, to ensure concrete quality.

2. Control Temperature Stress Distribution
Construction technicians should reasonably optimize aggregate gradation, using methods such as dry hard concrete and supplementary materials to minimize the cement content in the concrete. Mixing should be conducted according to actual temperatures, with strict control over the mixing speed to ensure uniformity. It is essential to set the pouring thickness based on temperature during concrete placement. When embedding water pipes in concrete, workers should first use cold water for cooling.

3. Prevent Foundation Settlement and Deformation
To effectively reduce the occurrence of foundation settlement and deformation, construction units can implement reasonable settlement joint designs. This approach can enhance the vertical stiffness of the building and improve its compressive strength. Additionally, utilizing some concrete to create rigid displacement can effectively lower the probability of foundation settlement issues when combined with this method. Technical personnel should pay close attention to this aspect during the design of construction plans, analyzing and summarizing factors that may affect foundation settlement at the construction site, and developing corresponding solutions to reduce the likelihood of cracking. The construction plan should detail waterproof measures for critical components to minimize the risk of leakage in external walls at these locations.

4. Emphasize Curing Measures
After completing the construction of concrete structures, construction units must strengthen their focus on curing work and implement effective curing measures to reduce the likelihood of cracking. Management staff should enhance supervision and management of the construction site, prohibiting unauthorized personnel from entering. Construction units must allow sufficient time for concrete to harden, which increases strength and load-bearing capacity. It is crucial to strengthen curing during the hardening period and avoid applying any external forces. Ensure that the thickness of the protective layer for reinforcement in control panels meets relevant technical specifications, and strictly control the strength of the formwork system. If small cracks appear, workers should promptly address them to eliminate potential hazards as early as possible, thereby improving the quality of concrete construction.