40
3214.013
McIntosh, J.D.
Insulation Journal
Article
Not Given
1965
March-April
65, 67, 69, 70
N
Blocks made from normal dense aggregates are available in all parts of the country. If the blocks are made from fully compacted concrete, as is sometimes done for special facing blocks, the density may be as high as 150 lb/ft3 and the compressive strength over 500 lb/in². But, more usually, the dense aggregate blocks are not fully compacted and the range of density of the material is about 105-120 lb/ft3, and the average strength may range from the minimum specified in B.S. 2028:1963 of 500 lb/in² to about 2000 lb/in². If cavities are incorporated in the block, as in the various designs of hollow blocks, the density of the block as a whole can be appreciably less than that of the material from which it is made; the standard permits up to 50% of void space.Blocks made from lightweight aggregates, such as well-burnt clinker, foamed or expanded slag or the newer proprietary lightweight aggregates, are most economically available near industrial areas where these aggregates are produced. The concrete density ranges from about 60 to 100 lb/ft3, and depends to some extent on the particular type of aggregate used; again, hollow blocks are available so that the density of the blocks themselves may be appreciably lower. The average strength of these blocks ranges from a specified minimum (again, B.S. 2028) of 400 lb/in² to about 1500 lb/in².
Aerated concrete blocks are manufactured by a process, quite different from that used for making dense and lightweight aggregate blocks, which gives them a uniform sponge-like texture. The range of density of the material–and of the blocks because they are only available as solid blocks–is generally from about 30 to 50 lb/ft3. These blocks have an average strength ranging from a minimum of 400 lb/in² to about 750 lb/in².