Concrete 1
Page 1: Reinforced Cement Concrete
Definition of RCC
Reinforced cement concrete (RCC) is a composite material that combines low tensile strength and ductility of concrete with higher tensile strength found in reinforcements, predominantly steel.
RCC addresses the limitations of concrete when used alone.
Concrete Properties
Concrete exhibits greater compressive strength compared to tensile strength.
Steel reinforcements are strategically placed in areas where tensile stress occurs.
Steel, being inherently stronger in tension, compensates for the weaknesses in concrete, forming a synergy when encased in hardened concrete.
Components of RCC
Reinforcement, primarily in the form of round steel bars (rebar), is embedded within concrete to enhance its properties.
Modern RCC may include alternative materials such as polymers alongside traditional rebar.
Page 2: Advantages and Disadvantages of RCC
Advantages of RCC
High Compressive and Tensile Strength: Allows it to withstand considerable loads.
Fire and Weather Damage Resistance: Suitable for diverse environmental conditions.
Durability: RCC structures last significantly longer due to their material properties.
Rigidity from Monolithic Nature: The continuous nature of RCC increases structural stability.
Low Maintenance Costs: Requires little upkeep over time.
Disadvantages of RCC
Labor-Intensive Production: Mixing, casting, and curing processes impact the final strength.
High Framework Costs: The need for robust frameworks inflates expenses.
Relative Weakness: Compared to steel, RCC has a lower compressive strength, leading to larger dimensions in certain structures.
Page 3: Reinforcement in RCC
Role of Rebar
Rebar, made from ridged carbon steel, provides frictional adhesion with concrete.
Essential for carrying tensile loads since concrete lacks tensile strength.
Desired Properties of Reinforcement
High Relative Strength
Tensile Strain Tolerance
Good Bonding with Concrete: Resistant to factors like pH and moisture.
Thermal Compatibility: Prevents undesirable stress during temperature changes.
Durability: Remains effective despite corrosive conditions.
Page 4: Special Concretes
Introduction to Special Concretes
Special concretes are tailored for specific applications—examples include lightweight, high-density, fire protection, and radiation shielding.
Concrete's natural drawbacks, mainly its low tensile strength and durability issues, have led to redesigns for improved performance.
Types of Special Concretes
Lightweight Concrete
High-Density Concrete
Plum Concrete
No Fines Concrete
Aerated Concrete
Fiber Reinforced Concrete (FRC)
Polymer Concrete
Ferro Cement
High Strength Concrete
High Performance Concrete
Comparison with Ordinary Concrete
Ordinary concrete is used for standard works, while special concrete caters to unique structural needs.
Ordinary ingredients: cement, sand, aggregate, and water. Special concretes may incorporate lighter aggregates or polymer binders.
Different construction techniques and performance properties are standard for special types, making them more costly compared to ordinary concrete.
Page 5: Lightweight Concrete
Definition and Characteristics
Lightweight concrete includes expanding agents to enhance volume while offering advantages like reduced dead weight and enhanced workability.
Primarily made using aggregates such as coke-breeze, cinder, or slag.
Advantages of Lightweight Concrete
Reduction of Dead Load: Facilitates smaller structural sections.
Cost-Effectiveness: Lower transportation and foundation costs.
Thermal Performance: Enhanced thermal comfort and reduced energy consumption in air-conditioned settings.
Use of Industrial Waste: Utilizes materials such as fly ash to reduce disposal issues.
Page 6: Aerated Concrete
Overview
Aerated concrete is lightweight and formed by embedding air bubbles in cement mortar to produce a sponge-like structure.
Also known as Gas Concrete or Foam Concrete, it consists mainly of water, cement, and finely crushed sand.
Typical densities range from 300 kg/m³ to 1000 kg/m³.
Applications of Aerated Concrete
Used in load-bearing walls, partition walls, precast panels, and insulation cladding.
Page 7: Uses and Applications of Special Concrete
Applications of High-Performance Concrete (HPC)
HPC is employed in high-stress environments, exemplified by significant structures like the Petronas Towers and Troll Platform.
Provides excellent durability and strength suitable for aggressive environmental conditions, valid for structures exposed to chlorides and sulphates.
Page 8: No Fines Concrete
Characteristics and Composition
Formed by excluding fine aggregates; consists of cement, coarse aggregates, and water only.
Makes use of single-sized aggregate, increasing voids to achieve unique properties.
Strength is dependent on mix ratios, achieving sufficient strengths for load-bearing applications in smaller buildings.
Page 9: Polymer Concrete
Classifications of Polymer Concrete
Polymer-Impregnated Concrete (PIC): Involves impregnating hardened concrete with a polymer for enhanced durability.
Polymer Portland Cement Concrete (PPCC): Incorporates latex instead of water in traditional mixes, enhancing strength and reducing corrosion risks.
Polymer Concrete (PC): Entirely composed of polymers, offering improved performance metrics.
Page 10: Prestressed Concrete
Definition and Components
Prestressed concrete undergoes initial compression via high-strength tendons to enhance performance against loads.
Tendons include single wires or multi-strands made from high tensile materials.
Applications
Commonly used in long-span structures like bridges, high-rise buildings, and industrial foundations.
Page 11: Advantages and Disadvantages of Prestressed Concrete
Advantages
Allows for factory production, enabling consistency and cost savings.
Enhances resistance to impacts and fatigue, and removes tensile stresses, promoting structural integrity.
Disadvantages
High initial costs and technical expertise required for construction and formwork.
Page 12: Ready Mix Concrete
Overview
Ready-mix concrete is manufactured in specialized facilities and delivered pre-mixed to construction sites, ensuring uniform mixing and reducing errors.
Advantages
Ensures quality control, reduces manual errors, saves labor, and minimizes wastage.
Page 13: Disadvantages of Ready Mix Concrete
Limitations
Transportation constraints make it less suitable for very remote sites.
Concrete's workability timeframe is limited, necessitating precise timing in delivery.