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Briefly, what tips would you like to pass on to the engineer in charge of mix proportioning on the subject of materials cost reduction?
Why is it not necessary to take into account durability considerations in concrete mix proportioning when the concrete is subject to normal exposure conditions?
In mix designing, why is it desirable to use a minimum amount of water? For a given slump, how can you reduce the amount of water?
Describe the significance of workability of concrete and the factors affecting the property.
Briefly state the influence of maximum aggregate size on the mixing water content and the cement content of a concrete mixture with a given water-cement ratio.
The proportions by mass for a concrete mixture are given as follows. If the unit weight is 2400 kg/m3, compute the cement content.
Determine the SSD mix proportions of concrete required for an outdoor pavement subject to frequent freeze-thaw cycles.
What is the principle behind consolidation of concrete mixtures? Describe the sequence of actions that take place in a fresh concrete mixture.
How would you define workability? Is workability a fundamental property of fresh concrete? If not, why?
Suggest at least two methods to reduce bleeding of a concrete mixture. Give significance and the factors affecting them: slump loss, segregation, and bleeding.
If this rate is too high from the standpoint of risk of plastic-shrinkage cracking, what precautionary measures would you take?
Define the initial and the final setting times as measured by the penetration resistance method (ASTM C-403).
What is the most efficient way of reducing the temperature of a fresh concrete mixture? Explain why.
What is the alkali-aggregate reaction? List some of the rock types that are vulnerable to attack by alkaline solutions.
What chemical reactions are generally involved in sulfate attack on concrete? What are the physical manifestations of these reactions?
List some of the common sources of sulfate ions in natural and industrial environments.
What is the effect of pure water on hydrated portland cement paste? With respect to carbonic acid attack on concrete, what is the significance of balancing CO2?
Discuss the significance of critical degree of saturation from the standpoint of predicting frost resistance of a concrete.
What modifications have been made to this hypothesis? Why is entrainment of air effective in reducing the expansion due to freezing?
Briefly explain the causes and control of scaling and D-cracking in concrete. What is the origin of laitance; what is its significance?
How does aggregate size influence the coefficient of permeability of concrete? What is the difference between erosion and abrasion?
What do you understand by the term durability? How much importance should be given to durability in the design and construction of concrete structures?
What is the usefulness of the extensibility concept? Why would high-strength concrete be more prone to cracking than low-strength concrete?
What is the significance of the term theoretical thickness? Which other factors determine the risk of cracking in a concrete element?
What are the typical ranges of drying shrinkage strain and creep strain in concrete; what is their significance?