Top Short question and answer from Concrete Technology in Civil Engineering Dae Civil Concrete technology short question
0AhmadDecember 10, 2023
Q: What is concrete technology in civil engineering? A: Concrete technology involves the study of the properties and behavior of concrete, a vital construction material.
Q: What are the primary constituents of concrete? A: Cement, water, aggregates (sand and gravel), and sometimes admixtures.
Q: How does water-cement ratio affect concrete strength? A: Lower water-cement ratios generally lead to higher concrete strength.
Q: What is the purpose of adding admixtures to concrete? A: Admixtures modify concrete properties, such as setting time, workability, and strength.
A: Workability is the ease with which concrete can be mixed, transported, and placed.
Q: What is the significance of the initial setting time of concrete?
A: Initial setting time is the time it takes for concrete to stiffen; it influences construction activities.
Q: How does the curing period affect concrete strength development?
A: Longer curing periods generally result in higher concrete strength.
Q: What is the purpose of adding pozzolans to concrete?
A: Pozzolans improve durability and reduce heat of hydration in concrete.
Q: How does the size of aggregates impact concrete strength?
A: Coarser aggregates tend to provide higher concrete strength.
Q: What is the role of air-entraining agents in concrete?
A: Air-entraining agents improve freeze-thaw resistance by creating tiny air bubbles.
Q: Explain the concept of the slump test.
A: The slump test measures the workability of fresh concrete by observing the slumping of a cone-shaped sample.
Q: What is the difference between high-strength concrete and normal-strength concrete?
A: High-strength concrete has a higher compressive strength compared to normal-strength concrete.
Q: How does the addition of silica fume affect concrete properties?
A: Silica fume enhances concrete strength and durability by filling voids and improving the matrix.
Q: What are the factors influencing the durability of concrete structures?
A: Factors include water-cement ratio, quality of materials, curing, and environmental conditions.
Q: How does the temperature during concrete placement impact its properties?
A: Extreme temperatures can affect setting time, strength development, and overall durability.
Q: Explain the term "hydration" in the context of cement.
A: Hydration is the chemical reaction between cement and water, forming the strength-giving compounds.
Q: What is the purpose of adding fibers to concrete?
A: Fibers enhance the toughness and crack resistance of concrete.
Q: How does the use of recycled aggregates impact concrete properties?
A: It can reduce strength, but proper processing and quality control can mitigate these effects.
Q: What is alkali-silica reaction in concrete?
A: It's a chemical reaction between reactive silica in aggregates and alkalis in cement, causing cracking.
Q: How can the workability of concrete be increased?
A: Use of water-reducing admixtures and proper mix proportions can increase workability.
Q: What is the significance of the water-cement ratio in concrete design?
A: It strongly influences the strength and durability of concrete; lower ratios are generally preferred.
Q: How do superplasticizers affect the flow of concrete?
A: Superplasticizers increase the fluidity of concrete without increasing water content.
Q: Explain the term "shrinkage" in concrete.
A: Shrinkage is the reduction in volume of concrete due to moisture loss during drying and curing.
Q: What is the purpose of adding color pigments to concrete?
A: Color pigments are added for aesthetic purposes in decorative concrete applications.
Q: How does the water absorption of aggregates impact concrete performance?
A: High water absorption can affect workability and durability, requiring adjustments in mix design.
Q: What is the role of silica gel in concrete production?
A: Silica gel is used to reduce alkali-silica reaction and improve concrete durability.
Q: How does the use of fly ash affect the environmental sustainability of concrete?
A: Fly ash, a byproduct of coal combustion, is a sustainable alternative to cement, reducing carbon emissions.
Q: What is the purpose of adding plasticizers to concrete?
A: Plasticizers improve the workability of concrete without significantly affecting water content.
Q: How can the durability of concrete in aggressive environments be enhanced?
A: Using corrosion-resistant reinforcement, proper curing, and incorporating additives for durability.
Q: Explain the concept of "pervious concrete."
A: Pervious concrete allows water to pass through, reducing runoff and aiding in groundwater recharge.
Q: What is the impact of curing temperature on concrete strength?
A: Higher curing temperatures can accelerate strength gain but may impact long-term durability.
Q: How does the use of air-entrained concrete benefit in cold climates?
A: Air-entrained concrete resists damage from freeze-thaw cycles in cold weather.
Q: What is the role of calcium chloride in concrete mixes?
A: Calcium chloride accelerates the setting time of concrete, especially in cold weather.
Q: How does the addition of fibers affect the permeability of concrete?
A: Fibers can reduce the permeability of concrete, improving its resistance to water penetration.
Q: What is the purpose of pre-stressing in concrete structures?
A: Pre-stressing increases the strength and load-carrying capacity of concrete structures.
Q: How does the use of silica fume impact the heat of hydration in concrete?
A: Silica fume reduces the heat of hydration, beneficial in controlling temperature rise in massive structures.
Q: What is the role of aggregate grading in concrete mix design?
A: Proper aggregate grading influences workability, strength, and durability of concrete.
Q: How does the addition of ground granulated blast furnace slag improve concrete properties?
A: It enhances workability, reduces permeability, and improves resistance to sulfate attack.
Q: What is the impact of over-vibration on fresh concrete?
A: Over-vibration can lead to segregation and affect the homogeneity of the concrete mix.
Q: How can sulfate attack be mitigated in concrete structures?
A: Using sulfate-resistant cement or incorporating mineral admixtures can mitigate sulfate attack.
Q: What are the challenges of using high-strength concrete in construction?
A: Challenges include reduced workability, increased sensitivity to curing, and potential for thermal cracking.
Q: How does the moisture content of aggregates affect concrete mix design?
A: Excessive moisture in aggregates may require adjustments to the water-cement ratio in the mix.
Q: What is the impact of using sea sand in concrete production?
A: Sea sand can contain chloride ions, posing a risk of corrosion in reinforced concrete; proper precautions are necessary.
Q: How does the addition of microsilica improve the performance of concrete?
A: Microsilica enhances strength, reduces permeability, and provides resistance to chemical attacks.
Q: What is the role of aggregates in controlling the thermal properties of concrete?
A: Aggregates can influence the thermal conductivity and expansion characteristics of concrete.
Q: How can concrete structures be designed for earthquake resistance?
A: Incorporating seismic design principles, such as proper reinforcement detailing and ductility, enhances earthquake resistance in concrete structures.
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