SSC JE 2023 Exam-Expected Questions from Concrete Technology

In the SSC JE Exam for Civil Engineering, the questions on Concrete Technology typically cover various aspects of concrete, including its properties, advantages, uses, and related concepts.

In this blog, we’ll provide you with some questions that you can expect in the upcoming exam.

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SSC JE 2023-Concrete Technology-Important Topics

You can expect questions related to:

1. Properties of Concrete: Questions may inquire about the properties of concrete, such as its strength, durability, workability, and shrinkage.
2. Cement and Aggregates: You might encounter questions about different types of cement, aggregates used in concrete mixtures, and their respective properties.
3. Water-Cement Ratio: Expect questions regarding the importance of the water-cement ratio and its influence on the quality of concrete.
4. Mix Design: Questions may focus on the mix design process, including the proportions of cement, aggregates, water, and admixtures required for specific concrete applications.
5. Workability: You might be asked about factors affecting concrete workability and methods to enhance or control it.
6. Curing and Quality Control: Questions related to the curing process, its significance, and quality control measures for concrete production may be included.
7. Special Concrete Types: Topics like high-strength concrete, self-compacting concrete, and lightweight concrete might be covered in questions.
8. Concrete Construction: Expect questions on concrete placement, compaction, finishing, and curing techniques.
9. Admixtures: You may encounter questions about different types of admixtures and their roles in concrete mixtures.
10. Hot and Cold Weather Concreting: Questions regarding the challenges and techniques for concrete placement in extreme temperatures may be part of the exam.
11. Repair and Maintenance: Questions on repairing and maintaining concrete structures might also be included.

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SSC JE 2023 Exam-Expected Questions from Concrete Technology

1.           Increase in the moisture content in concrete

(a) Reduces the strength

(b) Increases the strength

(c) Does not change the strength

(d) None of these

Sol-(a)

• An increase in moisture content, which corresponds to an increase in the water-to-cement (w/c) ratio, leads to a decrease in strength.
• According to Abram’s law, the strength of workable concrete only depends upon the w/c ratio. When the w/c ratio is increased, there is a corresponding decrease in strength, and this relationship is inversely proportional.

2.           The shrinkage of concrete

(a) Is proportional to water content in the mix

(b) Is proportional to cement content

(c) Increase with age of concrete

(d) (a) & (b) both

Sol-(d)

The term “Shrinkage” is commonly used to describe various volume changes in concrete resulting from moisture loss at different stages for various reasons. Shrinkage can be categorized into the following types:

1. Plastic Shrinkage:

• This occurs due to water loss through evaporation from the surface of the concrete.
• Concrete with a high-water content experience a more significant volume change.

2. Drying Shrinkage:

• This is caused by the loss of water in the gel pores of the concrete.
• Higher cement content leads to greater drying shrinkage.

3. Thermal Shrinkage:

• Seasonal and daily temperature variations cause concrete to expand and contract, resulting in thermal shrinkage.

4. Carbonation Shrinkage:

• Carbon dioxide (CO₂) in the atmosphere reacts with calcium hydroxide (Ca(OH)₂) in the concrete, forming calcium carbonate (CaCO₃).
• The new product (CaCO₃) occupies less volume, leading to shrinkage.
• Over time, the extent of shrinkage decreases.

3.           Which of the following method may be used for getting a more workable concrete?

(a) By increasing cement content

(b) By decreasing water-cement ratio

(c) By using angular aggregates in place of rounded ones

(d) By reducing the size of aggregates

(e) None of these

Sol-(a)

• Increasing the cement content in concrete results in a decrease in the aggregate-to-cement ratio.
• As the aggregate-to-cement ratio decreases, the workability of the concrete mix improves.
• This is because a reduced ratio means there is a greater quantity of paste available to effectively lubricate and coat the particles in the mix.

4.           Air entrainment in the concrete increases:

(a) Workability

(b) Strength

(c) The effect of temperature variation

(d) The unit weight

Sol-(a)

               Air entrainment in concrete introduces millions non-collapsing air bubbles, which function as flexible ball bearings and alter the properties of concrete in several ways:

               1. Increase in Workability:

               Air entrainment enhances the workability of concrete, making it easier to handle and place. The tiny air bubbles act as lubricants, improving the flow of the mix.

               2. Increase in Resistance to Freezing and Thawing:

               The presence of air bubbles helps concrete resist damage from freeze-thaw cycles. When water freezes and expands, these bubbles provide space for the ice to occupy, reducing the risk of cracking.

               3. Decrease in Segregation, Bleeding, and Permeability:

               Air entrainment minimizes the separation of ingredients in the concrete mix, preventing segregation and bleeding. It also reduces permeability, making the concrete less prone to moisture penetration.

               4. Increased Resistance to Chemical Attack:

               Air-entrained concrete exhibits improved resistance to chemical substances, which can help prolong its durability in aggressive environments.

5.           Steam curing of concrete is adopted for

(a) Precast structure

(b) Columns

(c) Beams

(d) Walls

Sol-(a)

• Steam curing is a curing method commonly used for precast concrete components with the primary objective of accelerating the rate of strength development.
• In this process, concrete members are exposed to steam at a temperature of 93°C, typically achieved through either low-pressure or high-pressure steam.

Here are some key effects and benefits of steam curing:

1. Accelerated Strength Development

2. Reduction in Shear Strength

3. Increased Resistance to Sulphate Action

4. Enhanced Resistance to Freezing and Thawing

Conclusion

It’s essential to thoroughly study the principles and practices of concrete technology, as these questions can vary in complexity and cover a wide range of topics related to concrete materials and their applications in construction. Be sure to refer to the official SSC JE syllabus and previous year’s question papers to get a better understanding of the specific topics and question formats that may appear in the exam.

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