Concrete Technology

What are the key properties of concrete that make it suitable for construction?

• The key properties of concrete that make it suitable for construction include its strength, durability, and ability to be molded into various shapes and sizes.

• The key properties of concrete that make it suitable for construction include its softness, flexibility, and inability to hold weight.

• The key properties of concrete that make it suitable for construction include its tendency to degrade quickly, inability to withstand weather conditions, and lack of versatility.

• The key properties of concrete that make it suitable for construction include its high cost, low availability, and inability to be formed into different shapes.

Explain the concept of mix design in concrete technology and its importance in construction.

• Mix design is not important in construction as any combination of concrete ingredients will result in the same quality of concrete.

• Mix design is the process of selecting ingredients based on their color and appearance, without considering their impact on the concrete's properties.

• Mix design in concrete technology refers to the process of selecting suitable ingredients and determining their proportions to produce concrete with desired properties. It is important in construction as it ensures the strength, durability, and workability of the concrete, leading to the successful completion of the project.

• Mix design is the process of randomly combining different concrete ingredients without any specific proportions, leading to weak and unreliable concrete.

Discuss the various concrete construction techniques used in the industry.

• Some of the concrete construction techniques used in the industry include formwork, reinforcement, pouring, finishing, and curing.

• Using cardboard as formwork

• Pouring the concrete in a single layer

• Skipping the curing process

1.     If 1500 g of cement is required to have a cement paste 1875 g of normal consistency, the percentage of water is,

• 20%

• 25%

• 30%

• 35%

M10 grade of concrete approximates

• 1 : 3 : 6 mix

• 1 : 1 : 2 mix

• 1 : 2 : 4 mix

• 1 : 1.5 : 3 mix

Concrete gains strength due to

• Chemical reaction of cement with sand and coarse aggregates

• Evaporation of water from concrete

• Hydration of cement

• All the above

Tricalcium aluminate (C3A)

• Reacts fast with water

• Generates less heat of hydration

• Causes initial setting and early strength of cement

• Does not contribute to develop ultimate strength

What is the depth the needle in Vicat apparatus should penetrate into the cement paste in consistency test?

• 33-35 cm from bottom of the mould

• 33-35 mm from top of the mould

• 33-35 cm from top of the mould

• 33-35 mm from bottom of the mould