Construction Material Testing

Question 1

1. Concrete is a mixture of ___.
   A. Cement + water + aggregate B. Cement + sand only C. Cement + clay D. Water + lime

Answer 1

✅ Answer: A – Basic ingredients of concrete.
Binding paste + aggregates = solid mass.

Question 2

2. Water-cement ratio mainly controls ___.
   A. Strength B. Workability C. Durability D. All of these

Answer 2

✅ Answer: D – All depend on w/c ratio.
Lower w/c → higher strength but less workable.

Question 3

3. Typical w/c ratio for normal mix concrete = ___.
   A. 0.25 B. 0.40–0.60 C. 0.75 D. 1.0

Answer 3

✅ Answer: B – Between 0.4–0.6 for most design mixes.*

Question 4

4. Standard compressive strength test for concrete uses specimens ___.
   A. 150 mm cube / 150×300 mm cylinder B. 100 mm cube C. Beam D. Brick

Answer 4

✅ Answer: A – Per ASTM C39 / NSCP 702.*

Question 5

5. Standard test age for concrete strength = ___.
   A. 3 days B. 7 days C. 14 days D. 28 days

Answer 5

✅ Answer: D – 28 days = f′c basis.*

Question 6

6. The compressive strength f′c is defined as ___.
   A. Max load / area B. Average stress C. Yield load D. Failure strain

Answer 6

✅ Answer: A – f′c = P/A of specimen.*

Question 7

7. Typical modulus of rupture (f_r) ≈ ___.
   A. 0.5 √f′c B. 0.62 √f′c C. 0.7 √f′c D. f′c

Answer 7

✅ Answer: B – ACI formula for flexural strength.*

Question 8

8. Slump test measures ___.
   A. Workability B. Strength C. Durability D. Air content

Answer 8

✅ Answer: A – Ease of placement.*

Question 9

9. Standard slump cone height = ___.
   A. 200 mm B. 300 mm C. 450 mm D. 600 mm

Answer 9

✅ Answer: B – 300 mm high, 100–200 mm base top.*

Question 10

10. Acceptable slump for reinforced beam concrete = ___.
    A. 25–50 mm B. 75–100 mm C. 150–200 mm D. 0 mm

Answer 10

✅ Answer: B – Medium workability for RCC.*

Question 11

11. Fine aggregate = materials passing ___.
    A. No. 4 sieve B. No. 40 C. No. 100 D. No. 200

Answer 11

✅ Answer: A – 4.75 mm ( No. 4 sieve ).*

Question 12

12. Fineness modulus (FM) of sand ranges ___.
    A. 2.3–3.1 B. 1.0–2.0 C. 3.5–5.0 D. 0.5–1.0

Answer 12

✅ Answer: A – Indicates coarseness.*

Question 13

13. Bulking of sand is caused by ___.
    A. Moisture film on particles B. Organic content C. Silt D. Air voids

Answer 13

✅ Answer: A – Thin water film causes apparent volume increase.*

Question 14

14. Aggregate impact test indicates ___.
    A. Toughness B. Hardness C. Durability D. Strength

Answer 14

✅ Answer: A – Resistance to impact load.*

Question 15

15. Los Angeles Abrasion test measures ___.
    A. Hardness and wear resistance B. Crushing C. Porosity D. Tensile strength

Answer 15

✅ Answer: A – Aggregate abrasion resistance.*

Question 16

16. Specific gravity of cement ≈ ___.
    A. 2.0 B. 2.5 C. 3.15 D. 4.0

Answer 16

✅ Answer: C – Typical for OPC.*

Question 17

17. Initial setting time of Portland cement ≥ ___.
    A. 15 min B. 30 min C. 45 min D. 60 min

Answer 17

✅ Answer: B – Per ASTM C191 / PNS 07.*

Question 18

18. Final setting time ≤ ___.
    A. 2 hrs B. 4 hrs C. 6 hrs D. 8 hrs

Answer 18

✅ Answer: B – Within 4 hours max.*

Question 19

19. Soundness of cement checked by ___.
    A. Le Chatelier test B. Vicats needle C. Blaine test D. Compression test

Answer 19

✅ Answer: A – Expansion test to prevent cracking.*

Question 20

20. Specific gravity of coarse aggregate ≈ ___.
    A. 2.4–2.9 B. 1.5–2.0 C. 3.5–4.0 D. >4.0

Answer 20

✅ Answer: A – Normal rock aggregate range.*

Question 21

21. Tensile test of reinforcing steel determines ___.
    A. Yield stress and ultimate strength B. Shear C. Fatigue D. Impact

Answer 21

✅ Answer: A – Per ASTM A615 bar specs.*

Question 22

22. Typical yield strength of Grade 60 rebar = ___.
    A. 275 MPa B. 415 MPa C. 420 MPa D. 600 MPa

Answer 22

✅ Answer: C – ≈ 420 MPa ( 60 ksi ).*

Question 23

23. Rebound hammer test is used for ___.
    A. Non-destructive strength estimation B. Density C. Moisture D. Creep

Answer 23

✅ Answer: A – Surface hardness → approx strength.*

Question 24

24. Ultrasonic pulse velocity test checks ___.
    A. Cracks and uniformity B. Compressive strength C. Slump D. Density

Answer 24

✅ Answer: A – Detects voids & cracks.*

Question 25

25. Standard curing temperature for specimens = ___. A. 20 ± 2 °C B. 27 ± 2 °C C. 30 °C D. 40 °C

Answer 25

✅ Answer: B – ≈ 27 °C ( room temp Philippine standard ).*