Engineering Materials·MCQ explained

The binding material in the mortar is also called:

Try it first: pick an option, then read the explanation.

Correct answer: D. Matrix

Detailed Explanation: The Matrix in Concrete and Mortar

In composite materials science, a matrix is the continuous phase that surrounds and binds the dispersed phase (the filler). In concrete and mortar, the cement paste (cement + water) acts as the matrix, while the aggregates are the dispersed filler. This terminology is used in both materials science and civil engineering standards.

Why D (Matrix) is correct: The cement paste forms a continuous network that fills the spaces between aggregate particles and bonds them together — exactly the role of a matrix in composite theory. An admixture is a chemical additive, not the binder itself. A paste describes the cement-water mixture before it hardens but is not the standard technical term for the binder component in composite-material terminology. Adulterant refers to an impurity that degrades quality.

Terminology in Concrete Composites

TermMeaning in Concrete Context
MatrixHardened cement paste — the binding phase
Aggregate (filler)Sand and gravel — the dispersed inert phase
AdmixtureChemical added to modify properties (plasticiser, retarder, etc.)
AdulterantUnwanted impurity (clay, silt, organic matter)

Key Concepts for Students

  • Concrete is a two-phase composite: matrix (cement paste) + reinforcement/filler (aggregates).
  • The quality of the matrix-aggregate interfacial transition zone (ITZ) often governs concrete strength more than the strength of either phase alone.
  • The term matrix appears in IS standards and in structural analysis of fibre-reinforced concrete (FRC) where fibres are embedded in the cement matrix.