Masonry Magazine February 1962 Page. 16
Build A Picture Window (well almost) Into Your Fallout Shelter
Develop high density glass bricks, which transmit natural daylight, yet have same radiation protection as solid concrete. The three layers of 3-inch thick as illustrated above let in 54 percent of the available light, which is more than that of many glare-reducing glasses used in office buildings.
The Pittsburgh Corning Corporation has announced a new material for use in fallout shelters that may solve one of the problems of shelter construction.
The problem is how to gain the practical and psychological advantages of natural daylight without sacrificing protection against radiation.
The material is a high density, solid glass brick. The bricks are annealed during production for exceptional strength.
The important feature of the material for shelter builders is that its high density-149 pounds per cubic foot-is equal to that of solid concrete! Density, or mass, is the key factor in stopping deadly gamma radiation.
The Office of Civil Defense has advised Pittsburgh Corning that the product meets their requirements for use in fallout shelters when substituted on an inch for inch thickness basis for concrete. In practice, the bricks would be installed back to back in a wall and would give the same amount of protection as an equal thickness of concrete.
Light transmission through the material is quite good. One 3-inch brick has a light transmission factor of over 80 per cent. Three of these together a total of 9 inches of solid glass still transmit 54 per cent of the available light. This is more light than transmitted through a quarter-inch of the glare-reducing glass often used in modern office buildings.
According to Civil Defense authorities, light is one of the most important requisites for shelter living, and ranks immediately after the absolute necessities of air, water and food.
Through the use of adequate thicknesses of solid glass bricks, available natural light can reach the interior of the shelter. This will allow the performance of certain tasks and ease the strain on limited battery-powered light sources. In addition, the added light, together with limited vision, would be an important morale factor to those in the shelter.
The solid glass bricks are produced in two sizes: a "5-inch brick" which is 5 inches by 5 inches square and 2 5/8 inches thick; and an "8-inch brick" which is 8 inches by 8 inches square and 3 inches thick. The edges are plastic coated to provide a better bond with mortar. Weight of the 8-inch brick is 16.5 pounds; the 5-inch brick weighs 5.7 lbs. Compressive strength is 80,000 pounds per square inch; modulus of elasticity is 10,000,000 pounds per square inch. Price, of course, will vary with location, but company officials estimate the 8-inch square units will cost from $3 to $4 each and the 5-inch square brick about $1.25 each.
Two sizes of solid glass bricks are available. Unit at left is 8-inches square and 3-inches thick. Smaller brick at right is 5-inches square and 2 5/8-inches thick. Edges are plastic coated for better mortar bond. MASONRY FEBRUARY