Durability is a critical factor in the construction of sewage treatment plants. These facilities are constantly exposed to harsh chemical environments, fluctuating water levels, and biological agents. Micro Silica Concrete, known for its enhanced properties, has emerged as a promising material for such demanding applications. As a supplier of Micro Silica Concrete, I have witnessed firsthand its performance in various sewage treatment projects. In this blog, I will delve into the durability of Micro Silica Concrete in sewage treatment plants, exploring its key characteristics and benefits.
Understanding Micro Silica Concrete
Micro Silica, also known as silica fume, is a by - product of the silicon and ferrosilicon alloy production. It is a fine, amorphous powder with extremely small particle size. When added to concrete, it reacts with calcium hydroxide produced during the cement hydration process to form additional calcium silicate hydrate (C - S - H) gel. This reaction, known as the pozzolanic reaction, significantly improves the properties of the concrete.
Micro Silica Concrete offers several advantages over traditional concrete. It has higher compressive strength, better workability, and improved resistance to chemical attack. These properties make it an ideal choice for sewage treatment plants, where the concrete structures are subjected to aggressive chemical and physical conditions.
Chemical Resistance
One of the primary challenges in sewage treatment plants is the exposure to various chemicals. Sewage contains a mixture of organic and inorganic substances, including acids, alkalis, and salts. These chemicals can react with the concrete, causing corrosion and deterioration over time.
Micro Silica Concrete exhibits excellent chemical resistance due to its dense microstructure. The pozzolanic reaction between micro silica and calcium hydroxide reduces the porosity of the concrete, making it less permeable to chemicals. This means that harmful substances have a harder time penetrating the concrete and causing damage.
For example, in the presence of sulfuric acid, which is commonly found in sewage, traditional concrete can experience sulfate attack. Sulfate ions react with the calcium hydroxide and calcium aluminate hydrates in the concrete, forming expansive compounds that can cause cracking and spalling. Micro Silica Concrete, however, has a lower calcium hydroxide content and a more stable C - S - H gel structure, which makes it more resistant to sulfate attack.
In addition to acid resistance, Micro Silica Concrete also shows good resistance to alkalis. In sewage treatment plants, some processes may involve the use of alkaline chemicals. The dense structure of Micro Silica Concrete prevents the ingress of alkalis, protecting the concrete from alkali - aggregate reaction, which can lead to expansion and cracking of the concrete.
Resistance to Biological Attack
Sewage treatment plants are home to a wide range of microorganisms, including bacteria, fungi, and algae. These biological agents can cause damage to the concrete structures through various mechanisms. For instance, some bacteria can produce acids as metabolic by - products, which can corrode the concrete. Fungi and algae can grow on the surface of the concrete, causing discoloration and weakening the surface layer.
Micro Silica Concrete has better resistance to biological attack compared to traditional concrete. Its dense surface makes it less hospitable for the growth of microorganisms. The reduced porosity means that there are fewer pores and crevices for the microorganisms to attach and grow. Additionally, the improved chemical resistance of Micro Silica Concrete protects it from the acids produced by bacteria.
Abrasion Resistance
The flow of sewage in treatment plants can cause abrasion on the concrete surfaces. The suspended solids in the sewage, such as sand and gravel, can act as abrasives, wearing away the concrete over time. Micro Silica Concrete has high abrasion resistance due to its increased compressive strength and dense structure.
The fine particles of micro silica fill the voids in the concrete matrix, making it more compact and harder. This results in a concrete surface that can withstand the abrasive action of the flowing sewage. In sewage treatment plants where there are high - velocity flows or a large amount of suspended solids, Micro Silica Concrete can significantly extend the service life of the concrete structures.
Durability in Fluctuating Water Levels
Sewage treatment plants often experience fluctuating water levels. The concrete structures are alternately submerged in water and exposed to the air. This cyclic wet - dry condition can cause damage to the concrete, such as freeze - thaw damage in cold climates and carbonation in the exposed parts.
Micro Silica Concrete is more resistant to these effects. Its low permeability reduces the amount of water that can penetrate the concrete. This means that there is less water available for freezing and thawing, reducing the risk of freeze - thaw damage. In addition, the dense structure of Micro Silica Concrete slows down the process of carbonation, which can lead to the corrosion of the steel reinforcement in the concrete.
Case Studies
There have been numerous successful applications of Micro Silica Concrete in sewage treatment plants around the world. In one project, a sewage treatment plant in a coastal area was facing severe corrosion problems due to the high salt content in the sewage. The original concrete structures were deteriorating rapidly, and frequent repairs were required.
After replacing the damaged parts with Micro Silica Concrete, the plant noticed a significant improvement in the durability of the structures. The new concrete showed no signs of corrosion or deterioration even after several years of operation. The reduced maintenance costs and extended service life of the structures made Micro Silica Concrete a cost - effective solution for the plant.
Applications in Different Parts of Sewage Treatment Plants
Micro Silica Concrete can be used in various parts of sewage treatment plants, including:
Primary Settling Tanks
These tanks are used to separate the solid particles from the sewage. The concrete walls and floors of the primary settling tanks are exposed to the abrasive action of the settling solids. Micro Silica Concrete's high abrasion resistance makes it an ideal material for these structures.
Aeration Tanks
Aeration tanks are used to provide oxygen to the microorganisms in the sewage for the biological treatment process. The concrete in these tanks is exposed to both water and air, as well as the chemicals used in the aeration process. Micro Silica Concrete's resistance to chemical attack and its ability to withstand fluctuating water levels make it suitable for aeration tanks.
Secondary Settling Tanks
Similar to primary settling tanks, secondary settling tanks are used to separate the treated sewage from the remaining solids. Micro Silica Concrete can ensure the long - term durability of these tanks, reducing the need for frequent repairs.
Conclusion
In conclusion, Micro Silica Concrete offers excellent durability in sewage treatment plants. Its chemical resistance, resistance to biological attack, abrasion resistance, and performance in fluctuating water levels make it a superior choice for the construction of concrete structures in these harsh environments.
As a supplier of Micro Silica Concrete, I am confident in the quality and performance of our product. We offer a range of Micro Silica products, including For Hong Kong Silica Fume, Micro Silica for Construction, and White Micro Silica, to meet the diverse needs of our customers.
If you are involved in the construction or renovation of a sewage treatment plant and are looking for a durable and reliable concrete solution, I encourage you to contact us for a detailed discussion. We can provide you with technical support and guidance to ensure that you select the right Micro Silica Concrete product for your project.
References
- Mehta, P. K., & Monteiro, P. J. M. (2014). Concrete: Microstructure, Properties, and Materials. McGraw - Hill Education.
- Neville, A. M. (2011). Properties of Concrete. Pearson Education.
- ACI Committee 201. (2008). Guide to Durable Concrete. American Concrete Institute.