Ready-mixed concrete, commonly referred to as simply "concrete," is a versatile and widely used construction material that is manufactured in a batching plant or concrete plant and delivered to construction sites in a ready-to-use form. It is a mixture of cement, water, aggregates (such as sand, gravel, or crushed stone), and sometimes admixtures, which are added to enhance the properties of the concrete. Ready-mixed concrete is produced in standard formulations based on established industry standards and guidelines, making it a reliable and consistent material for construction projects.

Composition of Standard Ready-Mixed Concrete:

Cement: Cement is a key ingredient in concrete and is responsible for providing the binding properties that hold the mixture together. Portland cement, which is made by grinding clinker (a combination of limestone, clay, and other minerals) with gypsum, is the most commonly used type of cement in ready-mixed concrete production.

Water: Water is required for the chemical reaction between cement and other materials, known as hydration, which results in the hardening and setting of the concrete. The amount of water used in the concrete mix is carefully controlled to achieve the desired consistency, workability, and strength of the concrete.

Aggregates: Aggregates, which include sand, gravel, or crushed stone, make up the bulk of the volume of concrete. They provide the structural strength and stability to the concrete, and their properties, such as size, shape, and gradation, can influence the workability, strength, and durability of the concrete.

Admixtures: Admixtures are chemical additives that are used in ready-mixed concrete to improve its properties or performance. They can be added during the mixing process to modify the properties of the concrete, such as setting time, workability, strength, or durability. Common types of admixtures include water reducers, accelerators, retarders, air entrainers, and plasticizers.

Production Process of Standard Ready-Mixed Concrete:

The production of standard ready-mixed concrete begins at a batching plant or concrete plant, where the concrete ingredients are carefully measured and mixed according to established mix designs. Mix designs are based on the specific requirements of the project, such as strength, durability, workability, and environmental conditions.

  1. Batching: The batching process involves measuring and combining the cement, water, aggregates, and admixtures in the correct proportions based on the mix design. This is typically done using computer-controlled equipment that ensures accurate measurement and consistent mixing.
  2. Mixing: Once the ingredients are batched, they are mixed thoroughly to form a homogenous mixture. The mixing process is typically done in a rotating drum mixer, where the materials are agitated together to form a uniform consistency.
  3. Transportation: Once the concrete is mixed, it is loaded onto special trucks, known as transit mixers or agitator trucks, for transportation to the construction site. These trucks are equipped with rotating drums that keep the concrete in a liquid state during transit, ensuring that it remains fresh and workable upon arrival at the construction site.
  4. Delivery: At the construction site, the concrete is discharged from the transit mixer and placed in the designated location using various methods, such as chutes, pumps, or conveyors. The concrete is then leveled, compacted, and finished according to the specific requirements of the project.

Properties of Standard Ready-Mixed Concrete:

Standard ready-mixed concrete is designed to meet specific performance requirements based on established industry standards and guidelines. The properties of ready-mixed concrete can vary depending on the mix design, which is tailored to the specific requirements of the project. Some of the key properties of standard ready-mixed concrete include:

  1. Workability: Workability refers to the ease with which concrete can be mixed, placed, and finished. It is influenced by factors such as water content, aggregate gradation, and admixtures used in the mix. The workability of ready-mixed concrete is crucial for ensuring efficient and effective placement and finishing of the concrete at the construction site.
  2. Strength: The strength of ready-mixed concrete is a critical property that determines its load-bearing capacity and durability. The strength of concrete is typically specified in terms of compressive strength, which is the maximum load that the concrete can withstand without failure. The strength of ready-mixed concrete can be adjusted by varying the mix design, including the type and amount of cement, aggregates, and water used.
  3. Durability: Durability refers to the ability of concrete to resist various environmental and chemical factors, such as freeze-thaw cycles, chemical attacks, abrasion, and corrosion. The durability of ready-mixed concrete is important for ensuring the longevity and performance of the concrete structure over its service life. Admixtures, such as air entrainers and chemical admixtures, can be used in the mix design to improve the durability of the concrete.
  4. Setting time: The setting time of ready-mixed concrete is the time it takes for the concrete to change from a plastic state to a solid state. It is an important property that affects the handling and finishing of the concrete. The setting time of concrete can be controlled by adjusting the type and amount of cement, water, and admixtures used in the mix.
  5. Density: The density of ready-mixed concrete refers to its mass per unit volume. It is an important property that affects the weight and stability of the concrete structure. The density of concrete can be influenced by the type and amount of aggregates, cement, and water used in the mix.

Advantages of Standard Ready-Mixed Concrete:

  1. Quality and Consistency: Standard ready-mixed concrete is produced in batching plants under controlled conditions, ensuring consistent quality and performance. The mix design is based on established industry standards and guidelines, which ensures that the concrete meets the specific performance requirements of the project. This results in a reliable and consistent material that can be used for various construction applications.
  2. Time and Labor Savings: Ready-mixed concrete eliminates the need for on-site batching and mixing, saving time and labor costs. The concrete is delivered to the construction site in a ready-to-use form, eliminating the need for extensive on-site preparation and reducing the overall construction time. This can result in faster construction schedules and cost savings.
  3. Customization: Ready-mixed concrete can be customized to meet the specific requirements of the project. The mix design can be tailored to achieve the desired strength, workability, and durability based on the project specifications. This allows for flexibility in designing and constructing different types of concrete structures.
  4. Quality Control: Ready-mixed concrete production involves rigorous quality control measures, including testing and monitoring of raw materials, mix design, and finished concrete. This ensures that the concrete meets the required performance criteria and quality standards. Additionally, ready-mixed concrete is produced in batch quantities, allowing for better control of material quantities and proportions, resulting in consistent quality.
  5. Versatility: Standard ready-mixed concrete can be used for a wide range of construction applications, including foundations, slabs, walls, columns, beams, and more. It can be used in various types of construction projects, such as residential, commercial, industrial, and infrastructure projects. Ready-mixed concrete can also be used in combination with other construction materials, such as steel reinforcement, to create reinforced concrete structures.