CCIL Concrete 3

Question 1

What does the water-to-cementing materials ratio (w/cm) primarily control in hardened concrete?

Accepted Answer

Strength and durability

Answer

The w/cm ratio is the most influential factor controlling both compressive strength and durability of hardened concrete.

Question 2

According to ASTM C1064, the maximum allowable time between sampling fresh concrete and completing the temperature measurement is:

Accepted Answer

5 minutes

Answer

ASTM C1064 requires the temperature of freshly mixed concrete to be measured within 5 minutes of obtaining the sample.

Question 3

Supplementary cementing materials (SCMs) such as fly ash are added to concrete primarily to:

Accepted Answer

Improve workability, reduce permeability, and lower heat of hydration

Answer

Fly ash and other SCMs react pozzolanically to improve long-term strength, reduce permeability, and lower heat of hydration in concrete.

Question 4

Which ASTM standard covers the Standard Test Method for Density, Absorption, and Voids in Hardened Concrete?

Accepted Answer

ASTM C642

Answer

ASTM C642 covers the determination of density, absorption, and voids in hardened concrete specimens.

Question 5

In cold weather concreting per ACI 306, concrete temperature at the point of placement should be maintained at a minimum of:

Accepted Answer

5°C (41°F)

Answer

ACI 306 requires concrete temperature at delivery to be at least 10°C (50°F) for thin sections to support hydration and early strength gain.

CCIL - Canadian Council of Independent Laboratories Practice Test