S C F F I C I E S T units have been fabricated to erect a fourroom house (Figure 3). This house is one single unit and others could be piled upward and outward in almost any way desired to form apartment houses. The size of the units themselves permits of considerable variety of interior arrangement. One important feature of this house is the large horizontal panels which impart a considerable degree of dignity to the house, so that, in spite of the flat roof, i t does not look like a dry-goods box. For this house, only four different kinds of Microporite units are required: floor, partition, and two outside wall slabs. With the increase in size of the units, very great strains are concentrated on the few remaining joints so that great care must be exercised to provide adequate resilience combined with complete adhesion between the joint material and the units. For this purpose strips of rubber, which have been protected against weathering by the use of suitable antioxidants, are cemented to the units b y means of a special glue made by mixing concentrated rubber latex with aluminous cement (3). I n addition, the Morbelli sheets are so shaped as to provide a lap in the horizontal joint. To carry the prefabrication to its logical conclusion, the interior surfaces of the Microporite slabs should receive their final finish in the factory. For this purpose several different treatments have been developed with due reference to the porosity and high absorbing power of the units. When paints are applied, i t is necessary to thin the first coats to secure penetration. For plaster finishes very lean mixes with protein binders have given excellent results, while for protect,ing the underside of the floor slabs and the upper side of the roof slabs, cut-back asphalts are satisfactory. For floor surfaces, Morbelli cement, pressed wood, or natural woods may be used. The roof is of standard felt and t a r construction. Steel casement windows and standard wood doors are being used, but the mechanical equipment has been developed by the John B. Pierce Foundation for this purpose.
Classification of Brick by Water Absorption . ‘
WALTER C. VOSS Massachusetts Institute of Technology, Cambridge, Mass.
Q I
S THE midst of current interest in better
houses and structures, there is a large and important field for scientific investigation of the individual units of the building materials of which these structures are built. Recent investigations have undertaken to explore some of the physical properties of that ancient building unit, the clay brick. These investigations include study of the capillary characteristics of various bricks by measurement of water absorptive properties.
Water Absorption by Brick When a clay brick which is highly porous comes into contact with wet mortar, it immediately absorbs water from the mortar, makes the mortar comparatively dry a t the interface, and introduces a variable condition which profoundly influences the strength of the mortar bond. When the porosity is low, it may fail to remove sufficient water from the
TO THE John B. Pierce Foundation and to its director of research, Robert L. Davidson, grateful thanks are due for supplying the funds for this development work.
Literature Cited (1) Bessey, G. G., Building Research Special Rept. 21, London, H. M.Stationery Office, 1934. (2) Bond, A. E., U.S. Patent 1,940,528 (Dec. 19, 1933). (3) Ferrari, F., Rev. matdriaux construction trav. publics, No. 283 (1933); Industria Cemento, 31, 13-16 (1934). (4) Huttemann and Csernin, U. S. Patent 1,932,971 (Oct. 31, 1933). (5) Ippach, Hugo, and Bieligk, Otto, French Patent 760,117 (Aug. 5, 1933). (6) Kuhl, Hans, 2’onind.-Ztg., 57, 1144-16 (1933). (7) Mensel, C . -4., J . Am. ConcreteInst., 6, 1 2 5 4 8 (1934). ( S ) Miller, D. G., Proc. Am. SOC.Testing Materials, 30, Part 11, 636-53 (1930). (9) Peffer, H. C., Harrison, R. L., and Shreve, R. N., IND.EXQ CHEM.,25, 719-22 (1933). (10) Thorvaldson, T., and Vigfusson, V. A., Eng. J . , 11, 174-80 (1928); Thorvaldson, T., and Shelton, G. R., Can. J . Research, 1, 148-54 (1929). (11) Vigfusson, V. 9.. Bates, G. N., and Thorvaldson, T . , Can. J . Research, 11, 520-9 (1934).
FIGURE 1. ABSORPTOMETER
RECEIVED April 27, 1935.
KOISELESS M O T O R OPERATED B Y GERMANY. Experiments conducted
DRY-ICEDEVEliOPED
IN
by a German dry-ice research organization in the use of dry-ice for the noiseless operation of motors, are alleged to have achieved complete success, with promise of far-reaching effects in motor construction and technic. I t is reported that the first motor using dry-ice has been completed and has given satisfactory results in operation; the motor is said to be characterized by very simple construction, high efficiency, and very light weight, and to embrace various
innovations.
mortar; again the strength of the mortar bond is adversely affected. A method of establishing a quantitative measure of a brick’s tendency to take mater from the mortar has been devised, which is based upon determination, in a special apparatus called the “Absorptometer, ” of the amount of absorption and rate of absorption of water by an immersed brick. The absorptometer (Figure 1) is a special arrangement of a balance, a clock, and an immersion tank, with which apparatus a continuous record of the changing weight of an immersed brick is obtained. Since the change of weight of the immersed 121
SEPTEMBER, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
1023
Conclusions
penetrated because of the opening up of a connecting channel by volume changes. -
Even though the significance of all observed variations in absorption properties may not be completely understood, these properties aid in classifying the results observed in practice and permit a number of interesting generalizations:
These studies in absorption lead to a conclusion that brick nlay have many different sorts of internal structure. Figure 3 illustrates several possible structures all gradations of which probably occur in actual brick. Careful study of an absorp&on curve gives indication of the class of structure to whiih the brick belongs. Thus, structure a would undoubtedly be like brick B26 (Figure 2) ; b like B25; and c, although rarely encountered in practice, is approached by B23. I n the course of this investigation, which has explored only a few phases of brick research, i t has become evident that most brick lack homogeneity, not only within each group as determined by pit and manufacture, but within the unit itIt mould Seem that research aimed toward elimination of this condition is highly desirable and would probably contribute much to the fund of information we now possess.
(1) For a given type of clay and manufacture, a high percentage of absorption is found in a brick .rrith a high coefficient of saturation. ( 2 ) A high coefficient of saturation is indicative of interconnecting capillaries or a specific gravity approaching that of the minute clay particles themselves. Such a brick underburned, and coupled v.-ith weathering, is unstable and of poor quality. (3) low coefficient of saturation shows sealed pores and capillaries, and may easily indicate vitrification. (4) A rapid rate of absorption in the early increments of time
+
indicates fine capillary structure, while a high percentage but moderate rate of absorDt,tion,as shown for Brick ~ 2 (pipure 6 2), indicates an open capiliary structure. absorption curve which has abrupt changes indicates (5) partially sealed capillary planes or voids M hich are suddenly
Rostone Operations Improvements have been made in Rostone, both as to method of manufacture and as to form of product. Rostone reactions have been applied to produce a building block of many desirable properties from easily available raw materials. Some 90 per cent of these raw materials is fly ash, a waste material from the combustion of powdered coal, disposal of which frequently presents a difficult problem.
R. L. HARRISON, P. W. JONES, AND
R. NORRIS SHREVE Rostone, Inc., Lafayette, Ind.
T
HE building material known as Rostone, made from the reaction of naturally occurring aluminosilicates, such as shales and slates, with a n alkaline earth base in the presence of lowpressure steam, has been described.' At the Century of Progress in Chicago there were two houses with exterior walls made of this material. In Indiana, Illinois, and Ohio a number of buildings have also been constructed whose exterior and interior walls are made of this product; numerous other jobs have employed Rostone, such as refronting old buildings, tiling bathrooms, floors, kitchens, etc. By the choice of various fillers and coloring materials, Rostone products may be given unusual and varied appearance and texture a t the command of the designer. Furthermore, the finished indurated product can be made to exact and predetermined dimensions. 1 Peffer, H C , H a r r i s o n , R L , a n d Shreve. R N , 719 (1933)
IVD E U GC H E V ,2 5 ,
RECEIVED May
io, 1935
Over six million people walked down the Rostone stair treads in one of the houses at the Century of Progress during the seasons of 1933 and 1934. The wear was remarkably small-under one-quarter inch a t the edges and less on the main surface. New Rostone Plant
To meet the market requirements, a new manufacturing plant has been established within the past year. The procedures adopted are similar to those previously described which involve the following steps : quarrying and powdering of shale; mixing of shale with fully slaked lime; incorporation of filler and coloring matter, together with the necessary amount of water; compressing of this moist material into requisite shapes; induration of this compressed material by heating in a n autoclave with steam of about 75 pounds per square inch pressure for 2 hours; treating the surface, when necessary, by grinding or by pebbling. The new plant involves efficient handling of the material in a streamline flow. A revolving covered mixer has been found satisfactory for excellent mixing of the materials. Since this reaction involves the combination between solids facilitated by steam, it is readily understood that efficient mixing and compressing are necessary as a prerequisite. Figure 1 shows on the right the storage hoppers from which the prepared moist mixture is dropped into the molds, which are then subjected to compression in the hydraulic press on the left. This press is capable of compressing, to 2500 pounds per square inch, large slabs 25 X 50 inches in size. Experience with this press has shown the advantage resulting from such uniformly even compression, for the particles are brought into intimate contact, thus facilitating reaction during the indurating or steaming stage. Although for several houses large slabs, 18 X 48 X 2 inches in size and weighing about 140 pounds, were used, experience has indicated that smaller slabs, 16 X 24 X 1.25 inches in size, are more advantageous, since one man can place them more easily on the supports. Furthermore, the reduction of thickness from 2 to 11/4inches means that a lighter framework can be used for the support of the slabs. In the earlier work the appearance of the slabs was improved by polishing the outer or exposed surface, but in the last year or two a surface has been produced which has been more pleasing, particularly for exterior work, by roughening the surface by means of an air blast uhing steel shot. Thiq
