Concrete is one of the most used and versatile building materials in construction. It consists of several components in different proportions that combine to create a strong and durable material. It is important for civil engineers and other professionals in the construction industry to understand the various components of concrete and their interactions.
In this article, we discuss the various commonly used concrete ingredients and their impact on properties and performance.
The main components of concrete are cement, water and aggregates (fine and coarse). Additionally, there are additives such as additives and fillers that are often used to improve the properties of concrete as needed depending on the structure's requirements.
The general composition of concrete components is as follows.
| material | composition |
| cement | 10 to 15% |
| Water | 15 to 20% |
| Aggregates (coarse and fine grains) | 65 to 75% |
Let us discuss the main component of concrete in detail.
cement
Cement is the crucial binding agent that holds everything together. It is a powder made from burnt limestone and clay. The cement reacts with water to form a paste that coats the aggregate and hardens over time. The cement hydration reaction is exothermic, meaning that heat is generated as it hardens.
The four main clinker compounds C3S, C2S, C3A and C4AF as well as gypsum are added after grinding, cement . To improve certain cement properties, the relative proportions of various components can be changed. The following table shows the typical distribution of clinker materials according to the ASTM standard.
| Type of cement | Use of cement | C 3 S | C 2 S | C 3 A | C 4 AF | CS̄ 2 |
| I | General purpose | 55 | 17 | 10 | 7 | 6 |
| II | Moderately resistant to sulfates | 55 | 20 | 6 | 10 | 5 |
| third chapter | High initial strength | 55 | 17 | 9 | 8th | 7 |
| 4 | Low heat of hydration | 35 | 40 | 4 | 12 | 4 |
| v | Sulfate resistant | 55 | 20 | 4 | 12 | 4 |
There are many types of cement which are used depending on the requirement of the structure. Furthermore, the cement content varies depending on the durability and strength requirements to produce different types of concrete.
Water
Water is the second most important ingredient in concrete. It is used to hydrate the cement and form the paste that holds the aggregates together. Without water, concrete would be a dry, brittle powder. However, too much water can affect the strength and durability of the final product.
Coarse aggregates
Aggregates are the inert fillers that make up the majority of concrete. They can be thin or thick depending on the intended use. Coarse aggregates are typically used in thicker concrete mixes, while Fine aggregates are used in finer mixes. The size and distribution of aggregates also affect the properties of concrete.
As we need a gradation of materials, fine to coarse aggregates are used to produce concrete. The majority of concrete is occupied by coarse aggregate, which becomes the main component of concrete.
Fine aggregate
Fine aggregates fill cavities in coarse aggregate, one of the main components of concrete. Previously, river sand was used as fine aggregate. However, given the growing demand for construction materials and the environmental impact of the extensive use of river sand, alternatives were sought.
Manufactured sand and sea sand are not the most popular substitutes for river sand today. Of these, manufactured sand is more popular compared to sea sand because it has many limitations such as the removal of harmful chemicals contained in it.
Additives other than concrete ingredients
Although cement, water and aggregates are the concrete components of traditional concrete, modern concrete has taken it to another level. There are many additives that can be added to concrete to modify and improve its properties.
Some of these additives are as follows.
Additions
Additives are used to change the properties of concrete. The addition of an additive can change the setting time, reduce the water content, improve the workability of the concrete, etc.
New generation additives such as superplasticizers have taken this field to the next level.
fly ash
Fly ash is used as a substitute for cement. It's thinner than concrete. It is mainly used to reduce the heat of hydration. In general, replacing it with fly ash can reduce cement content by up to 35%.
silica powder
Concrete is one of the best materials. It is finer than cement and fly ash. Silica fume has a larger surface area and can therefore be used effectively in construction.
Mixing proportions of concrete components
The proportion of these components is very important to produce strong and durable concrete. The mixing ratio of concrete is determined based on several factors. Overall, the result of concrete mix ratio depends on the concrete mix. The concrete qualities are related to the following.
- Exposure condition
- Cover the rebar
- Water-cement ratio
- Minimum cement content and cement content
