 QUESTION

# Three concrete masonry units (CMU) are tested for compressive strength, with the following average results: Failure Load = 825 kN Gross Area = 0.

1. Three concrete masonry units (CMU) are tested for compressive strength, with the following average results:

Gross Area = 0.079 m2

Gross Volume = 0.015 m3

Net Volume = 0.011 m3

Determine the following:

a. Would these CMUs be classified as solid or hollow?

b. What is the average compressive strength based on net area?

c. Does this satisfy ASTM C90 requirements for compressive strength of load-bearing CMUs? Note: metric values are given in lecture notes.

2. A portion of a normal-weight CMU was tested for absorption and moisture content. The following results were obtained:

Mass of unit as-received = 8.0 lb

Saturated mass of unit = 8.6 lb

Oven-dry mass of unit = 7.6 lb

Apparent immersed mass of unit = 4.5 lb

Calculate the following: (a) absorption in lb/ft3; and (b) moisture content in as-received condition aspercent of total absorption.

Determine if the absorption meets ASTM C90 requirements. If not,state the potential consequences of using this unit in construction.

3. A clay brick is tested for absorption and saturation coefficient with the following results:

Dry mass of brick = 2175 g

Saturated mass after 24-hour cold water submersion = 2455 g

Saturated mass after 5-hour boiling water submersion = 2470 g

Calculate absorption by 24-hour submersion, absorption by 5-hour boiling, and the saturation coefficient. Compare to the ASTM C62 requirements for building bricks and determine theappropriate weathering grade for this brick.

4. Describe the reason(s) for potential material incompatibility between clay brick veneer walls and astructural concrete frame. How can proper design and construction details be employed to avoidsuch problems?