Concrete: Types, Properties, and Applications
What is ACI?
ACI stands for the American Concrete Institute. It is an organization that develops and publishes standards and regulations for concrete construction.
Compressive vs. Tensile Strength of Concrete
Concrete is very strong in compression but relatively weak in tension.
What is the PCA?
PCA stands for the Portland Cement Association.
What is Portland Cement?
Portland cement is a hydraulic cement. Hydraulic cement sets and hardens by reacting chemically with water. It is produced by pulverizing clinker, composed essentially of hydraulic calcium silicates, and usually contains one or more forms of calcium sulfate as an addition during milling.
Tricalcium Aluminate Cement Characteristics
Tricalcium aluminate cement is characterized by a fast reaction rate, a large amount of heat released, and relatively poor durability.
Distinguishing Characteristic of Type V Cement
Type V cement is distinguished by its resistance to sulfate attack. It’s used in structures exposed to high sulfate levels, such as sewers.
Recommended Use of Type III Cement
Type III cement is recommended for structures where high early strength is required.
Effect of Air Entrainment in Concrete
The inclusion of air in concrete increases the workability of the mixture during placement and improves resistance to freeze-thaw cycles. However, it can reduce the concrete’s strength, and it also reduces the water/cement ratio.
Heavy Aggregates and Their Uses
Heavy aggregates are a type of aggregate used for nuclear safeguards, and protection against X-rays, gamma rays, and neutrons.
Volume of Coarse Aggregate in Concrete
Coarse aggregate typically makes up 60% to 80% of the concrete volume.
Influence of Aggregate Size on Air Entrainment
The finer the aggregate size, the greater the percentage of air-entraining additive needed.
Importance of Texture in Concrete Structures
It is important that concrete presents a dense texture so it can withstand adverse weather conditions.
Comparison: Roman Concrete vs. Modern Concrete
Roman Concrete
- Used volcanic sands with cementitious properties.
- Contained potsherds with pebbles.
Modern/Architectural Concrete
- Better finish on concrete surfaces.
- Can be finished smooth with excess cement.
- Primarily functional and resistant, but not inherently aesthetic.
- Aesthetic solutions include: painted cement, use of white or colored cement, etc.
Steel Reinforcement in Concrete
Besides corrugated rods, other steel reinforcement presentations include:
- Corrugated Wires
- Welded wire mesh (plain or corrugated)
- Reinforcement rods with 60,000 psi or higher yield strength.
Advantages of Steel Reinforcement
- Resists tensile stresses resulting from applied loads.
- Strengthens the compression zone of concrete beam sections.
- Reduces long-term deformations.
- Can resist high forces in both tension and compression.
What is Architectural Concrete?
Architectural concrete is a type of concrete that offers a better finish on concrete surfaces, presenting different aesthetic solutions: painted cement, use of white or colored cement, exposed aggregates, uneven surfaces, etc.
Difference Between Lightweight and Heavyweight Concrete
Lightweight concrete is used in harsh environments with thermal factors. Heavyweight concrete is used for very compact structures such as nuclear stations, for protection against X-rays, gamma rays, etc.
Regulations and Systems Governing Concrete Design
- ACI (American Concrete Institute)
- ASTM (American Society for Testing and Materials)
- English System
- SI Metric System