Functions of Cement and Aggregate in Concrete

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Questions and Answers

What are the two main components that define the workability of concrete?

Compaction and segregation

Consistency and cohesiveness (correct)

Voids and strength reduction

Density and strength ratio

Why is sufficient workability a vital property for the finished concrete product?

It allows for maximum compaction with reasonable effort.

It reduces the amount of voids in the concrete.

It increases the strength ratio of the concrete.

All of the above (correct)

What is the relationship between voids in concrete and its strength?

5% voids can lower strength by 10%.

Voids have no effect on concrete strength.

5% voids can lower strength by 30%. (correct)

2% voids can lower strength by 30%.

What is the primary function of cement in concrete?

To provide strength. Signup and view all the answers

What is the primary function of aggregate in concrete?

To provide volume and reduce cost. Signup and view all the answers

What is the primary function of water in concrete?

To provide hydration for the cement. Signup and view all the answers

What is the primary function of cement in concrete?

To bind the aggregates together Signup and view all the answers

Why is water added to the concrete mixture?

To increase the workability and facilitate placement Signup and view all the answers

What is the primary function of aggregates in concrete?

To provide the majority of the volume to the concrete Signup and view all the answers

Which characteristic of normal-weight concrete is mentioned in the text?

It generally weighs about 2400 kg/m³ Signup and view all the answers

What is the primary reason for using fine aggregate in concrete?

To fill the voids in the coarse aggregate Signup and view all the answers

Which statement about the functions of constituents in concrete is true?

Cement fills the voids in the aggregate and binds them together Signup and view all the answers

Which factor influences the workability of concrete by decreasing the interparticle friction?

Water content Signup and view all the answers

What aggregate characteristic requires more water to act as a lubricant, resulting in lower workability?

Irregular shape and rough texture Signup and view all the answers

For a constant water/cement ratio, how does the workability of concrete change with the aggregate/cement ratio?

Increases Signup and view all the answers

What is the main factor that influences the workability of concrete according to the text?

Water content Signup and view all the answers

In concrete, why is a well-graded aggregate preferred?

Least amount of voids in a given volume Signup and view all the answers

What happens to the strength of concrete with a 10% reduction in density?

50% reduction in strength Signup and view all the answers

Study Notes

Workability of concrete is a composite property with two main components: Consistency (mobility of concrete) and Cohesiveness (water-holding and aggregate-holding capacity).
Workability is crucial for achieving maximum density during compaction with a reasonable amount of effort, as voids in concrete can significantly reduce its strength.
The functions of constituents in concrete include cement filling voids and binding aggregates, aggregates providing volume and stability, and water aiding in adhesion, workability, and hydration of cement.
Three types of concrete based on unit weight are normal-weight concrete (2400 kg/m3), lightweight concrete, and heavyweight concrete.
Factors affecting workability include water content (higher water/cement ratio reduces strength), aggregate type and gradation (finer particles require more water, larger aggregate size increases workability), aggregate/cement ratio (lower ratio increases workability), and aggregate grading (well-graded aggregates have fewer voids).

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Description

Explore the roles of cement and aggregate in concrete construction, including filling voids, binding aggregates, imparting strength, providing volume stability, and more.