# Concrete Technology Questions and Answers – Strength and Durability Relationship

This set of Concrete Technology Multiple Choice Questions & Answers (MCQs) focuses on “Strength and Durability Relationship”.

**1. Strength of concrete increase with _____________**

a) Increase with w/c ratio

**b) Decrease with w/c ratio**

c) Decrease in size of aggregates

d) Decrease in curing time

**Explanation**: As previously stated, concrete strength is inversely related to the w/c ratio.

**2. Strength of concrete increase with _________**

a) Increase with w/c ratio

**b) Increase in fineness of cement**

c) Decrease in size of aggregates

d) Decrease in curing time

**Explanation:** The fineness of the cement increases the strength of the concrete.

**3. Approximate ratio of the strength of the cement conc of 7 days to that of 28 days (2/3)?**

**a) .75**

b) .85

c) 1

d) 1.15

**Explanation:** The pier cylinder with extra water broke at 1980 psi after the lab shattered the seven-day cylinders. The pressure in the other seven-day cylinders reached 2620 psi.

**4. Approximate ratio of strength of the 30 cm cube to that of 15 cm cube is _____________**

a) 1.1

b) 1

**c) .9**

d) .75

**Explanation:** According to Eurocodes, the strength of a cylinder with a diameter of 15cm and a height of 30cm is approximately 0.84 of the strength of a 15x15x15 cm cube.

**5. Approximate ratio of direct tensile strength to flexural strength is ____________**

a) .25

b) .33

**c) .5**

d) .05

**Explanation**: Approximate ratio of direct tensile strength to flexural strength is .5 according to the formula.

**6. Durability of concrete is proportional to _________**

a) Sand content

b) Water cement ratio

c) Aggregate ratio

**d) Cement aggregate ratio**

**Explanation:** Due to differences in the thermal characteristics of the aggregates and cement paste, volume chances exist.

**7. Strength of concrete show an increase with _________**

a) Decrease in rate of loading

**b) Increase in rate of loading**

c) Unaffected by rate of loading

d) Depends on application of load

**Explanation:** Strength of concrete is directly proportional to the nature of the loading.

**8. Strength of concrete is ___________**

**a) fck=K(cC+W+A)2**

b) fck=K(C+AC+W+A)2

c) fck=K(C+WC+W+A)2

d) fck=K(C+W+AC+W+A)2

**Explanation:** When we have the volume of cement, aggregates, and water, we can use this formula to calculate the strength of concrete.

**9. As per & 5456:200 Young’s modulus of concrete is _______________**

a) 1000 fck

**b) 5000 fck2**

c) 5700 fck

d) 150 fck

**Explanation:** 5000 fck2 is the formula of young’s modulus of the concrete according to IS 5456:200.

**10. Strength of concrete is proportional to ______________**

a) Sand content

b) Water cement ratio

c) Aggregate ratio

**d) Cement water ratio**

**Explanation:** Concrete strength is proportional to the cement water ratio and inversely proportional to the water-to-cement ratio.

Concrete’s durability can be characterised as its capacity to withstand weathering, chemical attack, and abrasion while retaining its desired engineering qualities. Depending on the exposure environment and intended qualities, different concretes require varied levels of durability. The impact of sulphate anions on concrete deterioration owing to sulphate attack and the role of chloride ions on sulphate attack in plain and blended cements are linked to the influence of cement types on concrete durability.