INDUSTRIAL .4ND ENGISEEKING CHEh‘IISTRY
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pulverized form to which ha5 been added, by a process of atomization and mechanical mixing, a relatively small percentage of a fat or oil of vegetable or animal origin. The waterproofing ingredient is formed and completely dispersed throughout the lime putty by the heat and the agitation of the boiling mass a t the time when the lime is slaked with water and hoed by the laborer on the job. This mixture of pulverized quicklime and fatty glycerides is a novel commercial product, patented in the United States and Canada. The permanent waterproofing ability of this product has been demonstrated not only by laboratory tests extending over several years, but by practical use in more than three hundred important new buildings, all free from leaks, and all practically free from efflorescence; the mortar has remained strongly water-repellent after weathering, in the case of the oldest buildings, through five successive winters. One of the outstanding examples is the new group of buildings of the Yale Divinity College a t New Haven, Conn., completed in 1932. About five million common brick were laid in a mortar made of 2 parts Rockland Waterproof Lime putty, 1 part Magnolia slag cement, and 9 parts sand, by volume. These buildings remain permanently dry and free from disfiguring efflorescence although built with brick not particularly free from soluble salts; they include some rather daring architectural features, such as projecting soldier courses of brick a t the base of the walls and groups of large circular columns, built entirely with this same brick and mortar. Waterproof Lime is also finding application for stucco. The failure of exterior stucco can usually be attributed t o cracking, leakinq, and disintegration due t o excessive volume change in the same manner as the failure of masonry mortars which are composed principally of dense, hard-setting cement. A high-lime mixture is particularly desirable for stucco, and the use of Waterproof Lime solves the one real problem by providing a stucco which is waterproof in addition to having the desirable quality of relative elasticity and freedom from cracking due to its minimum volume change. Another use of Waterproof Lime which may become a new and popular short cut in the plastering trade is the application 0
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of a washable and perniaiieiitly waterproof wall finish coat coinpoied of the simple mixture of colored Ifraterproof Lime putty and Keene’s cement.
New Cellophane Bags for Lime In the building construction trade the old-fashioned wooden barrel of lump quicklime is rapidly being replaced by pulyerized quicklime in special paper bags. Quicklime i. a perihhable product. It readily hydrates or air-slakes when exposed to air of average humidity, and hydrate.. very rapidly under conditions of the higher temperatures of summer. Pulverized quicklime is more susceptible than lump lime and, in view of the fact that lime will more than double its bulk volume by air slaking, the building of an inexpensive bag for pulverized quicklime was a difficult problem. Many called waterproof packages made of paper or burlap, treated with asphalt, wax, and other waterproofing conipoundq, are an excellent protection to the contents against actual dampness, but none of them is impervious to the passage of air. Lime in such packages when stored in piles and tightly cornpressed by the superimposed weight of the pile, seldom k e e p longer than 60 days before bursting the bag by the pressure of increased bulk due to air slaking. With the cooperation of the Valve Bag Company, a bag for quicklime has been developed which is air-tight as well a. moisture-tight. This is a multiwall-paper bag including one ply of laminated Cellophane paper. This laminated ply comprises a sheet of ordinary kraft paper and a sheet of du Pont waterproof Cellophane united with a thin coat of asphalt adhesive. This combination sheet is remarkably strong and is absolutely impervious to the passage of either moisture or air. Lime in these Cellophane bags has kept in perfect condition for over two years. Waterproof pulverized quicklime, hermetically jealed in these relatively inexpensive modern packages, can rightfully claim recognition as a new and valuable addition to the protlucts of the building construction niduqtry. 40-
RECEITED April 27, 1935.
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High-Lime Mortar for Leak-Proof Masonry FRANK LOFTUS Blue Diamond Service Corporation, S e w York, N. Y.
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TALL building with scaffolds hanging and men busy with mortar and pointing tools is eloquent of one thing-the masonry is leaking. There is no excuse for this condition. Three things are necessary for waterproof masonry-namely, the proper masonry units (brick, stone, ashlar, etc.), the proper mortar, and good workmanship. All of these are available if they are wanted. “If they are wanted” is significant, for they must be wanted sufficiently to be paid for, and then more must be paid to guarantee, through qualified and active supervision, that they are obtained. Let action follow the consideration of this simple proposition and there d l 1 be little or no trouble from leaky buildings. As proof, hundreds of buildings are standing whose owners have not known or will not know the trouble and expense that accrue from the use of improper or poor materials and workmanship in the erection of brickwork. Experience supports the statement that water-tight masonry is not possible unless the proper mortar is used.
The properties of a good mortar may briefly be .suiiiniarizetl as follows: 1. Good troweling properties. 2. Impermeability: a suit>ablestructure when hardened to resist the passage of water. 3. Adhesion: the ability to bond properly to the masonry units. 4. Flexibility: the ability to resist stresses due to temperature, settlement, wind, etc., Tvithout failure. 5. Minimum volume change. A mortar high in lime content possesses all of these properties. Since the total volume of joints in brickwork constitut’es a considerable part of the wall volume, the importance of using a mortar that is properly mixed in the right proportions of the right materials should be apparent to all who are concerned with water-tight brickwork.
Good Troweling Properties A mortar which has good troweling properties lightens the task of the bricklayer. If he is a capable mechanic, he is far
OCTOBER, 1935
INDUSTHIAL AND ESGISEERING CHEAIISTRY
more likely to produce good and proper workmanship with a material that adds t o his facility than with a material that reduces his speed and makes his work difficult. This is an important consideration in the matter of water-tight walls. Lime, because of its outstanding ability to retain water, stands above all other materials in producing a fat, easy-working mortar. Water is the sole lubricating medium of mortar.
Impermeability
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"The Properties of Bricks and Mortars and Their Relation to Bond" show conclusively that mortars richer in lime than the 1:1:6 mix have better bonding power than that mortar. As lime, either putty or dry hydrate, was substituted more and more for Portland cement, the bonding power was improved. The tensile strengths of mortar specimens were not actually measured in these tests. However, the tensile strength of mortar is approximately proportional to the corresponding compressive and transverse strengths which were measured.
Flexibility and Minimum Volume Change
In order for a inortar when hardened to resist the passage Proof of the superiority of lime mortar in regard to flexiof water, it is necessary for the voids in the sand to be combility is found in experimentation on mortar for chimney pletely filled. As an example, Cow Bay sand as a rule runs construction. Mortar meets its severest test when used for about 331j3 per cent void. The proportion of cementitious the sett'ing of brick in industrial chimney construction. Free material to sand, therefore, should be 1: 3, by volume. The standing, subject to cementitious mateterrific wind stressm, rial should certainly $a n d temperatures contain n o t less as high as 800" C. than 41i2 cubic feet inside, f r e q u e n t 1y of l i m e . If 4l/? coexistent with subcubic feet of cement z e r o temperatures are added, the reoutside, combine to sultant mortar is a place a terrific strain 1:1:6 mix. on the s t r iic t u r e . S e w York City Elasticity and adfurnishes conspicuhesion o f ni o r t a r ous e x a m p l e s of are absolutely necesleak-proof masonry sary for safety and in the Chrysler, permanence in Lincoln, and Daily c hirnne y construcNews buildings, and tion; thus a mortar the entire group a t rich in lime conRockefeller Center, tent-? parts lime, etc. 9 high degree 1 part' cement, 5 of impermeability parts sand by and adhesion charvolume-has been a c t e r i z e s the maproved experiniensonry mortar used CHRYSLER ASD CITYBANKFARMERS TRUSTCOMPAXY BUILDISGS t'ally to be best for in these buildings. WITH LEAK-PROOF MASONRY CONSTRUCTED chimney con>triicThe mortar was metion. Dared bv the Blue D i a m o i d Service Minimuin volume change is found in high-lime mortars. Corporation which operates a machine-mixed mortar service Volume change is reduced as the lime content is increased from two central mixing plants. The mortar was compoqed of and the cement content is decreased. Quoting froni a S a 9 cubic feet of aged lime putty (produced from 4l z cubic feet tional Lime Association booklet ( 1 ) : of pulverized quicklime) to the cubic yard of sand; 4 to 4', 2 cubic feet of cement are usually added to the machine-mixed The data shown in Table 13 of Bureau of Standard arch lime mortar as it is used a t the job. It is interesting to note Paper S o . 683. . show that when the extent of bond i. less that the 1: 3 machine-mixed lime mortar, with the addition of than 90 per cent of the flatside area of a brick, there is a tendency for it to be destroyed entirely if t,he mortar is one that has high four and one-half bags of cement, was specified by the archivolume changes subsequent t o hardening. tects for the Rockefeller Center development a t the time it was planned to erect the walls entirely of brick. S o chances The purpose of this paper is to point out the properties of a could be taken. Millions of dollars were to be spent on these good mortar. Comparisons n-ith high-cement mortar> have buildings and the walls had to be leak-proof. d high-lime not been made, and reports of many conclusive tests between mortar was needed for the job. The brick design was afterthese two kinds of mortars have been omitted although theqe wards changed to limeqtone ashlar, and 1: 3 lime mortar plus tests prore the value of lime. However, the Portland Cement four and one-half bags of cement mere used for the limestone Association which formerly recommended a 1:3 cement' niortar hacking. White sand with nonstaining cement in the same plus 10 or 15 per cent of lime for brick masonry, ~ i o wrecproportions was used in the setting of the limestone. Lime ommend a 1: 1:6 mortar for this purpose. Lime today stands mortar hardens through the absorption of carbonic acid gas for many reasons as the finest Tyaterproofing agent' obtainable. from the air and eventually goes back to its original state of Its history record is old and flawless, and, when all who have limestone-a hard, ryaterproof, everlasting substance. the responsibility of designing, specifying, and building leakproof masonry will stop to investigate this record, it. ti.-e in Adhesion or Bonding Power high quantities will be insisted upon. Obviously there is no more important consideration in reLiterature Cited gard to mortar than its power to adhere completely and uniformly at all points of contact, wherever brick and mortar (1) Natl. Lime dssoc., Bull. 321, 2nd ed., 1934. (2) Palmer, L. A , and Parsons, D. .L, Bur. Gtand:irds, Reaenvch meet, but the subject cannot posjibly be compressed into one Paper 683 (19341. paragraph. The following is quoted from data recently published by the Sational 13ureau of Standards ( 2 ): R E C E I V E D.\pril 27, 1935
