Masonry Magazine April 1993 Page. 12
Construction With the Speed of Light
Rotary kiln lightweight aggregate masonry... the smart way to conquer time and space.
Field Test: 8"x8"x16" Productivity
PRODUCTIVITY GAINS
1 COURSE 2
12%
Laboratory Test:
3
26%
Heavyweight
Profile
Productivity Comparison Tables
1. Size Factor: 24" Blocks vs. 16" Blocks
Lightweight
Profile
5
SIZE TYPE COURSES SEC/UNIT BLK/HR. RATE (SQ. FT/HR) RATE CHANGE
16" LW Avg. of 6
41.6 86.5
76.9
24" LW Avg.of 6
43.5
82.8
1104
+43.6%
16" HW Avg. of 6
478
75.3
66.9
24" HW Avg. of 6
51.6
69.8
93.1
+39.0
2. Weight Factor: Lightweight vs. Heavyweight
SIZE TYPE COURSES SEC/UNIT BLK/HR. RATE (SQ.FT/HR) RATE CHANGE
24" HW Avg. of 6
516 69.8
93.1
24" LW
Avg.of 6
43.5
82.8
110.4
+186
16" HW
Avg. of 6 47.8 75.3
66.9
16" LW
Avg.of 6
41.6 86.5
76.9
+14.9
3. Size & Weight Factors Combined: 24" Lightweight vs. 16" Heavyweight
SIZE TYPE COURSES SEC/UNIT BLK/HR. RATE (SQ.FT/HR) RATE CHANGE
16" HW Avg. of 6
47.8
75.3
66.9
24 LW Avg. of 6
43.5
82.8
110.4
+64.9
Average lightweight unit density is 93 lbs/cf Average heavyweight unit density is 130 lbs/cf
MASONRY process is believed to be one of the most labor intensive aspects of construction today. Since masonry units (blocks) must be handled and placed one-by-one, increased mason productivity is the key to effective management. In tests conducted both in the field and at the National Concrete Masonry Association Research and Development Laboratory, it has been dramatically shown that the size and weight of masonry units are primary factors influencing the speed at which blocks can be laid.
The test results confirm that lightweight block made with expanded shale, clay or slate aggregate significantly increased mason productivity over heavyweight units, especially when 24 units were used. These facts alone make lightweight block walls cost competitive with any other wall system.
But considering the reduced structural loading, better fire rating, greater strength, and much better thermal insulating and sound absorbing properties, lightweight concrete blocks are more than cost competitive. They are cost effective.
The productivity gained with 8"x 8"x16" (standard size) lightweight block is represented by the "Field Test" graph. Although productivity improvement varied from course to course, the graph shows there was a significant overall increase in productivity with the lightweight units.
The Productivity Comparison Tables are based on laboratory data compiled during the construction of four wall sections. The figures shown reflect averages for all six courses of each wall section.
Table 1 (Size Factor) compares 24" masonry units to 16" units. The table shows that the use of 24" masonry units significantly increases mason productivity: 39% with heavy-weight units: 43.6% with lightweight units.
In Table 2 (Weight Factor) the gains in productivity attributed to lighter weight are shown. Productivity increased 14.9% with 16" lightweight.
12 MASONRY-MARCH/APRIL, 1993