Concrete is a composite material manufactured by combining various components such as cement, sand, aggregate, and water with or without additives. Cement is the main binding agent used to bind other construction concrete materials together. It is used to make mortar and concrete during the construction process. The coarse aggregate forms the main body of the concrete, contributing to its overall strength by increasing its density.
Fine aggregate, such as sand, is used to fill the gaps between the large coarse aggregate and to “lock” larger pieces together. Sand helps reduce the amount of cement paste required and decreases the amount of shrinkage that could occur. Additives are added to improve or modify the properties of 26% fresh hardened concrete, such as plasticizers and retardants. Water is a key ingredient in concrete, as it contributes to the hardening process through hydration.
Its role is important in concrete because the strength of concrete depends to a large extent on the water-to-cement ratio and is the critical factor in the production of “perfect concrete”. Fly ash is also added to concrete to reduce the amount of cement required for concrete, which contributes to considerable cement savings and concrete manufacturing cost. After that, water is added according to the water-cement ratio. Sometimes it correlates with the property of water gains in concrete.
It is a specific form of segregation, in which part of the water in the concrete comes out to the surface of the concrete, being of the lowest specific gravity among all the ingredients of the concrete. This is how long it takes for concrete to obtain sufficient hardness. It was generally correlated with the setting time of the cement. In its simplest form, concrete is a mixture of paste and aggregates or rocks.
The paste, composed of portland cement and water, covers the surface of fine (small) and coarse (larger) aggregates. Through a chemical reaction called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete. Therefore, when dosing ingredients by volume, only materials corresponding to an integer number of bags of cement should be taken. The main ingredients have been the same, but new mixing technologies allow designers and engineers to fine-tune the final properties of fully set concrete. The amount of water used to mix these ingredients is by far the most important factor in determining the final strength of concrete.
The key to achieving a strong and durable concrete lies in careful dosing and mixing of all components. The proportion of ingredients changes the properties of the final product, allowing engineers to design concrete that meets their specific needs. While it is not generally considered an ingredient, a concrete mix includes between 1% and 9% entrained air. If the mixture is too stiff, add small amounts of water and cement while maintaining proper water-to-cement ratio until it's ready for use.