The number of ingredients in concrete are
Correct Answer: D. 4
📚 Detailed Explanation: Four Ingredients of Concrete
Concrete is defined as a composite material made by mixing specific proportions of four essential ingredients. Understanding the role of each ingredient is fundamental to all concrete technology topics.
Why D (4) is correct: The four ingredients of concrete are: (1) Cement — the binder that holds everything together through hydration. (2) Fine aggregate (sand) — fills voids between coarse aggregate particles, improves workability. (3) Coarse aggregate (gravel/crushed stone) — the bulk filler and structural skeleton. (4) Water — triggers cement hydration and provides workability for placing. A fifth ingredient, admixtures (plasticisers, retarders, air-entraining agents), is sometimes added but is optional — concrete by definition can be made without them.
The Four Essential Ingredients
| # | Ingredient | Role | Typical % Volume |
|---|---|---|---|
| 1 | Cement | Binder (hydration) | 10–15% |
| 2 | Fine aggregate | Filler, workability | 25–30% |
| 3 | Coarse aggregate | Structural skeleton, bulk | 35–45% |
| 4 | Water | Hydration, workability | 15–20% |
Key Concepts for Students
- The four ingredients = cement + fine aggregate + coarse aggregate + water — the most basic definition in concrete technology.
- Air (voids) makes up the remaining volume in concrete; its amount depends on compaction quality.
- Admixtures are the optional fifth component, added to modify specific properties but not part of the basic definition.