Several considerations for selecting functional concrete materials
Selecting concrete functional materials suitable for specific projects requires considering the following aspects:
I. Structural Requirements of the Project
1. Mechanical Properties
If the project requires high tensile strength, flexural strength, or impact toughness of concrete, such as bridges and roads, the addition of Steel fibers or other fibrous materials can be considered. Steel fibers can effectively enhance these mechanical properties of concrete, increasing the load-bearing capacity of the structure.
For structures that need to withstand high pressures, such as the foundations of high-rise buildings, the addition of mineral admixtures (such as slag powder) can improve the later strength of concrete to meet the project's compressive requirements.
2. Deformation Properties
In large-volume concrete projects, to prevent cracks caused by large shrinkage deformations due to temperature changes, expansive agents can be used. Expansive agents can compensate for the shrinkage of concrete, maintaining the integrity of the concrete structure.
For thin-walled structures prone to early plastic shrinkage cracks, such as thin slab concrete components, polypropylene fibers are a good choice. They can effectively suppress the formation of early cracks.
II. Durability Requirements
1. Impermeability
For underground structures (such as basements, underground tunnels, etc.) or hydraulic structures (such as pools, dams, etc.), it is necessary to improve the impermeability of concrete. Waterproofing agents or mineral admixtures like silica fume can be added. silica fume can fill the pores of concrete, making it more compact and thus enhancing its impermeability.
2. Corrosion Resistance
In marine environments or areas at risk of chemical erosion (such as buildings near chemical parks), the corrosion resistance of concrete should be considered. Adding corrosion inhibitors can prevent steel reinforcement corrosion, and selecting mineral admixtures with strong resistance to sulfate attack (such as slag powder) also helps to improve the corrosion resistance of concrete.
III. Construction Conditions
1. Workability Requirements
If the project uses pumping construction, concrete with good pumping performance is required. In this case, pumping agents can be used, which can improve the fluidity and cohesion of concrete, preventing it from blocking pipes during pumping.
In high-temperature construction environments, to delay the setting time of concrete, retarders can be used to ensure that concrete has enough time for construction operations.
2. Curing Conditions
For projects with poor curing conditions (such as difficulty in ensuring adequate water curing), functional materials such as water-retaining agents can be considered to reduce the evaporation of internal moisture in concrete and ensure normal hydration and hardening of concrete.
IV. Economic Considerations
On the premise of meeting all the performance requirements of the project, the costs of different functional materials should be comprehensively compared. For example, although silica fume has excellent performance, its price is relatively high. If the project's requirements for strength and durability are not extremely high, relatively cheaper mineral admixtures such as fly ash may be a more economical choice.
Some new functional materials (such as carbon fiber) are often costly and may not be chosen in general civil engineering projects due to poor economic performance unless there are special performance requirements.
