Application Guide for Readymix Concrete Production

Introduction

In the realm of construction, concrete stands as a fundamental material, serving as the backbone for various structures worldwide. Its versatility and strength make it indispensable for everything from residential buildings to infrastructure projects. Ready-mix concrete, in particular, offers a convenient and efficient way to deliver consistently high-quality concrete to construction sites. This application guideline delves into the production process of ready-mix concrete, focusing on grades B25, B30, B35, and B40, which denote different levels of compressive strength.

Understanding Ready-Mix Concrete

Ready-mix concrete refers to concrete that is pre-mixed and batched for delivery to construction sites. It is manufactured under controlled conditions, ensuring precise proportions of ingredients such as cement, aggregates, water, and admixtures. This meticulous preparation guarantees uniformity and optimal performance in various applications.

Production Process

Selection of Materials:

Cement: The type of cement used influences the properties of the concrete. Ordinary Portland Cement (OPC) is commonly used.

Aggregates: Typically, a blend of coarse and fine aggregates is used to achieve the desired strength and workability.

Water: The water-cement ratio is critical as it affects the strength and durability of the concrete.

Admixtures: These are added to modify the properties of fresh and hardened concrete, such as setting time, workability, and durability.

Mixing:

• The exact proportions of materials are calculated based on the desired grade of concrete.
• Mixing is usually done in a batching plant using equipment capable of ensuring uniformity and consistency.

Transportation and Delivery:

• Once mixed, the concrete is transported to the construction site in specialized trucks equipped with rotating drums to prevent segregation and maintain uniformity.

Placement and Curing:

• On-site, the concrete is poured into molds or directly into formwork.
• Curing involves maintaining adequate moisture and temperature conditions to facilitate hydration and achieve the desired strength.

Grades of Concrete

Concrete grades are classified based on their compressive strength, measured in megapascals (MPa) at the age of 28 days. The higher the grade number, the stronger the concrete. Here’s a breakdown of the grades covered in this application guideline:

B25: This grade indicates a compressive strength of 25 MPa after 28 days of curing.

B30: Concrete of grade B30 achieves a compressive strength of 30 MPa.

B35: B35 concrete reaches a compressive strength of 35 MPa.

B40: The strongest among the grades discussed here, B40 concrete attains a compressive strength of 40 MPa.

Mix Designs

• Our range of high-quality concrete mixes ensures superior performance for various construction needs. From B25 to B40, our OPC-based concretes are meticulously engineered to meet stringent standards and deliver exceptional durability and strength.

1. B25 Concrete Mix Design:

• Cement: 320 kg
• Water: 176 liters (Water-Cement Ratio = 0.55)
• Natural Sand: 330 kg
• Crushed Sand: 0 kg
• Coarse Aggregate: 1200 kg
• Superplasticizer: As per manufacturer’s recommendation

2. B30 Concrete Mix Design:

Cement: 360 kg

Water: 180 liters (Water-Cement Ratio = 0.50)

Natural Sand: 250 kg

Crushed Sand: 130 kg

Coarse Aggregate: 1180 kg

Superplasticizer: As per manufacturer’s recommendation

3. B35 Concrete Mix Design:

Cement: 400 kg

Water: 180 liters (Water-Cement Ratio = 0.45)

Natural Sand: 220 kg

Crushed Sand: 175 kg

Coarse Aggregate: 1160 kg

Superplasticizer: As per manufacturer’s recommendation

4. B40 Concrete Mix Design:

Cement: 440 kg

Water: 176 liters (Water-Cement Ratio = 0.40)

Natural Sand: 190 kg

Crushed Sand: 220 kg

Coarse Aggregate: 1140 kg

Superplasticizer: As per manufacturer’s recommendation

Notes:

Natural Sand vs. Crushed Sand: The mix designs above reflect the use of both types of sand based on the desired proportions to achieve optimal workability, strength, and durability.

1. Natural Sand:

Granulometry:

• Particle Size:

  • Generally ranges between 0.075 mm (No. 200 sieve) and 4.75 mm (No. 4 sieve).
  • The Natural Sand should be well-graded with a balance of fine, medium, and coarse particles.

Properties:

• Round to sub-angular particles.
• Smooth texture due to natural erosion.
• Typically contains higher amounts of fines (particles smaller than 75 µm), which can affect workability and water demand in concrete mixes.
• Generally sourced from riverbeds or natural deposits.

2. Crushed Sand (Manufactured Sand):

Granulometry:

Particle Size:

• Primarily ranges from 0 mm to 4.75 mm.
• The crushed sand should be well-graded with angular to sub-angular particles.

Properties:

• Rough texture due to crushing process.
• Higher mechanical strength compared to natural sand.
• Contains lower amounts of fines compared to natural sand, improving durability and reducing shrinkage potential in concrete.
• Produced by crushing rocks or quarry stones to meet specific grading requirements for concrete production.

3. Fine Aggregates (Combined Natural and Crushed Sand):

Granulometry:

• Particle Size: Ranges from 0 mm to 4.75 mm, combining both natural sand and crushed sand fractions.
• Fine aggregates should be a well-graded mix to optimize packing density and workability.

Properties:

• Balanced particle size distribution to fill voids between coarse aggregates.
• Influences workability, strength, and durability of concrete mixes.
• The Fine aggregates should be properly graded to meet ASTM C33 or other relevant standards, ensuring consistency and quality in construction applications.

4. Coarse Aggregates:

Granulometry:

• Particle Size: Generally ranges from 5 mm to 20 mm (or larger in some cases).
• The coarse aggregates should be a well-graded mix with a range of particle sizes for optimal packing density.

Properties:

• Clean, hard, and durable particles free from deleterious materials.
• Influences the strength and stability of concrete mixes.
• Provide bulk and stability to the concrete, enhancing mechanical properties such as compressive strength and modulus of elasticity.
• Shape and texture impact workability and bonding with cement paste in concrete.

5. Mix Design Properties:

• Water-Cement Ratio: Adjust to meet the specified slump requirements and to ensure proper hydration of cement while maintaining concrete performance.
• Superplasticizer: Use in accordance with directions specified in Technical Datasheets to maintain workability without increasing water content excessively, especially in mixes with higher proportions of crushed sand.

Key Features:

Strength and Durability: Each grade optimized for specific strength requirements, ensuring reliable performance over time.

Versatility: Ensure the mix design is suitable for thef application required (foundations, columns, slabs, and more).

Consistency: Produce the concrete using high-quality materials and advanced mixing techniques to ensure uniformity and reliability.

Admixtures: Select the concrete admixture that best enhances workability, durability, or early strength as per project demands.

Environmental Considerations: Minimize environmental impact without compromising performance.

Application Areas:

• Residential Construction
• Commercial Projects
• Infrastructure Development
• Industrial Applications

Certifications and Compliance:

• Ensure conformity to local and international standards for concrete strength and durability.
• Produce in accordance with environmental regulations and quality management systems.

Contact Information:

• Include contact details for sales inquiries, technical support, and customer service.