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Difficulty: EasyConcrete and Masonry Materials

In standard concrete mixtures, which ingredient undergoes a chemical reaction with water to bind the aggregate particles together?

  1. A
    Coarse gravel
  2. Portland cementAnswer
  3. C
    Fine silica sand
  4. D
    Hydrated lime

Answer

Portland cement is the primary hydraulic binder in concrete that reacts chemically with water.
Portland cement is the hydraulic binder in concrete. When combined with water, it undergoes a chemical hardening process called hydration, creating a crystalline paste that securely binds fine sand and coarse gravel into a solid mass.

Step-by-Step Solution

1
Identify the basic components of standard concrete and their mechanical functions.
Concrete is composed of coarse aggregate (gravel), fine aggregate (sand), water, and a binding compound (Portland cement).
Differentiating between inert filler aggregates and the chemically active matrix is necessary to determine the binder.
2
Determine which component chemically bonds the mixture through hydration.
When Portland cement mixes with water, an exothermic chemical reaction called hydration occurs, forming a solid rock-like structure that locks aggregates in place.
Aggregates remain inert, meaning Portland cement is the sole ingredient that creates the adhesive bond.

Key Concept

Composition of concrete and the binding role of Portland cement
Estimated Time:45s
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Topics

Concrete and Masonry Materials

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