Masonry Magazine October 1962 Page. 13
view of the wlite mine of Mont. The top mountain it mined off in 18 feet high. Buildings are in foreground.
test also proved that the fill supports its own in a cavity without settling. Additional settlement were made by pouring the material from heights one story, and comparing the original bag volume of material with the volume of the cavity. Vermiculite is a mineral, it meets the brick and dustry's requirement for an inorganic material. Comparative heat transfer tests of uninsulated and d brick and tile cavity walls and concrete block Pere conducted by Pennsylvania State University. The tests show that vermiculite masonry fill increases thermal efficiency of the wall more than 50 per cent. State reports also show that when water-repellent alite is poured into the cores, cold spots on the wall the webs do not occur, and that the inside temperature of the entire wall is substantially ed. One of the major advantages of the fill is the t environment" it provides for a building's oc- and the improved livability it creates in basement.
-repellent vermiculite reduces sound transmission masonry walls and partitions. This is of special nce to owners of motels, apartments, and similar occupancies.
Installation cost is low as little as 10 per square foot of wall area for labor and materials. One reason is the simplicity of installation. The fill is unusually pourable and flows readily around wall ties, electrical boxes, and conduit pipes. It can be poured at scaffold height directly from the bag into the cores or void, or into a hopper that is moved along the top of the wall. No rodding or tamping is needed. Walls 12 to 15 feet high can be filled in one pour, except for areas under window sills. Such areas must be filled before being capped, to assure a complete insulation job.
No vapor barrier is needed in regions of the United States and southern Canada when the average interior relative humidity does not exceed 50 per cent.
Water-repellent vermiculite is marketed nationally in four cubic foot bags that weigh about 30 pounds. The approximate coverage is:
Type of Wall
2" Cavity
2½" Cavity
4½" Cavity
6" Block (2 or 3 core)
8" Block (2 or 3 core)
12" Block (2 or 3 core)
Square Feet of Woll Area per 4 cubic foot bag
24
20
11
21 (23)½ blocks)
14% (16) blocks)
8 (9 blocks)
Tables giving insulation ("U") values are available from Vermi- culite lastitute.
MINING AND MILLING
The largest deposits of vermiculite in the United States are at Libby, Montana, and Travelers Rest, South Carolina. The Libby deposit has been mined longer. It was dis- covered in 1917 by prospectors searching for copper, manganese, and vanadium during World War 1. Serious work on the ore body started in 1923.
This deposit is a rounded mountain about 4,200 feet high. The entire top is being taken off by power shovels in terraces 18 feet high. The mine operates around the clock, winter and summer. As much as 10,000 tons of material are mined per day.
Ore that meets requirements is hauled to a primary plant at the edge of the deposit, where the larger rocks are removed. The smaller material goes down a chute 192 feet deep inside the mountain, and onto a conveyor belt 1,300 feet long, which takes the ore to the mill. (Turn to page 15)
ARY
October, 1962
13