ACI Certification Concrete Mix Design 2

Question 1

What does the fineness modulus (FM) of fine aggregate indicate?

Accepted Answer

An index of the overall coarseness or fineness of the aggregate

Answer

The percentage of material passing the No. 200 sieve

Answer

The specific gravity of sand

Answer

The absorption capacity of fine aggregate

Question 2

According to ACI 211.1, as the fineness modulus (FM) of fine aggregate increases, the recommended bulk volume of coarse aggregate per unit volume of concrete:

Accepted Answer

Increases

Answer

Decreases

Answer

Remains the same regardless of FM

Answer

Drops to zero

Question 3

What is the primary purpose of preparing trial batches during concrete mix design?

Accepted Answer

To verify that the calculated mix proportions meet specified requirements under actual conditions

Answer

To determine the unit weight of aggregate alone

Answer

To establish the compressive strength of neat cement paste

Answer

To calculate the water absorption of aggregates

Question 4

Which ACI document provides the standard practice for selecting proportions for normal, heavyweight, and mass concrete?

Accepted Answer

ACI 211.1

Answer

ACI 318

Answer

ACI 301

Answer

ACI 305R

Question 5

The saturated surface-dry (SSD) condition of aggregate is used as the reference state in mix design because:

Accepted Answer

It requires no moisture correction to batch water calculations

Answer

It requires the most additional water to be added

Answer

It represents the driest possible state of aggregate

Answer

It eliminates the need to measure aggregate specific gravity

Question 6

In concrete production, 'batch weights' refer to:

Accepted Answer

The actual quantities of all ingredients loaded into the mixer for one production batch

Answer

The weight of cement only in one batch

Answer

The weight of mixing water per batch

Answer

The weight of one cubic yard of hardened concrete

Question 7

According to ACI 318, the maximum w/cm ratio for concrete subjected to deicing chemicals (severe freezing-and-thawing exposure) is:

Accepted Answer

0.40

Answer

0.50

Answer

0.45

Answer

0.55