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OCR for page 51
PART THRE:E
PRESIDING CHAIRNIA~-
Howard T. Fisher
Howard T. Fisher ~ Associates, Inc.
Chicago, Ill.
Research
and New Technical
Developments
M R . C . E . S ~ ~ ~ ~ N G: Sometime during the confusion of ~ ~ a
Harvard education that incluclec] being a teacher, ~ ~ acting as consultant to
our Fecleral~ Government and the United Stations, 3 ~ research on land use.
housing and integrated buil(ling design, 4 ~ practicing as an architect.
5) presiding over a music school board of trustees, and 6) associating with
a variety of professional societies harboring consultants, architects, planners
ant! others, your next session chairman found tinge to erect a personal cor-
porate facade to cover his manifold activities. ~ ant sure you are all aware
of his solid professional accomplishments as an architect and a planner.
Ladies and gentTen~en, Mr. Howard T. Fisher, Howard T. Fisher & Asso-
ciates, Tnc., Chicago.
51
OCR for page 52
OCR for page 53
Thermal Performance
of Clay Masonry Walls
R . F ~ s H E R:
Mr. Walker this morning
made one statement that interested me espe-
cially and which T wrote down at the time.
He said substantialZy as follows: "The joining
of material is more important than the mate-
riaZ itself." This is a statement of the very
greatest importance in the construction indus-
try, and not perhaps generaZZy recognized by
all of the manufacturers o f materials and the
_1 'r _ r _ ' 1
architects, engineers who are concerned with
design.
Our first speaker this afternoon is Clarence
17\1onk, manager of the Structural Clay Prod-
ucts Research Foundation's Architectural
and Engineering Research Division. He is
IN recent years designers of air conditioning
systems have come to realize that predictions
of heat loads based on tile conventional cal-
culations (using the "U" factor) gave higher
C. B. Monk, Jr.
Structural Clay Products
Research Foundation.
Geneva, III.
particularZy concerned with this question of
the joining of materials not only how these
materials join, but how these materials join
other materials-how walls meet roofs how
f oors meet partitions, and so on.
Mr. Monk was an architectural engineer
with the Armour Research Foundation of the
Illinois Institute of Technology, and has been
an instructor in the civil engineering depart-
n~ent of that school anal in the mechanical
engineering department of the University of
ZZinois. He is a member of the American So-
ciety of Civil Engineers and the National
Society of Professional Engineers.
design requirements than the completed buiid-
ings demanded. This experience plus both
analytical and experimental findings have high-
lighted the importance of the influence of
53
OCR for page 54
density and specific heat of building materials
on the thermal transmission into and within
structures.
The usual way of making heat gain (or heat
loss ~ calculations is to think of some fixer!
outside temperature, perhaps 95° to lL05° F.
The inside temperature is usually chosen
from some control level, 70° to 80° F. The
fixed temperature difference between the
outside and inside temperature is the n~eas-
ure of the amount of air conditioning ~ or
heating) needed as calculated from the k or
U factor. The fallacy in these assumptions is
thinking in terns of a constant outside ten~-
perature. The inside temperature nary be con-
stant; we like to have it so. But since the sun
rises anc! sets every 74 hours, there is inevitably
a rise and fall of outside air ancT building sur-
face temperatures. This cycle in heat gains (or
losses) is affected to a n~arkec! extent by the
mass characteristics of the builcTing materials
(specific heat and density) as well as their
thermal transmission coefficients. Recent field
experience has shown that consideration of
the thennal transmission coefficients alone is
not a sufficient basis of calculation; specific
heat and density are equally important.
Specific heat is the measure of the amount
of heat requirec] to raise a certain quantity
of substance, we'll say; a pound, one degree of
temperature. Certainly it takes snore heat to
raise the temperature of one pound of water
one degree than of one pound of alun~inun~.
Archaeologists tell us that primitive Nan
soon learned that the continued warmth sus-
tained in the stone he heated to cook his food
was ren~arkably effective in keeping hint warns
over a perioc! of tinge after the fire cried out.
In the modern age, the hot water bottle is
familiar to all of us. This is a means of con-
veying heat by means of specific heat an
density.
In climatology the influence of n~aritin~e
bodies over continental lane] areas on te~-
~4
perature is well known. Cities near the Great
Lakes area enjoy higEcr temperatures cluring
the winter than cities in the central plains area
at the same latitude. The reason is that the
relatively higher specific heat of the water
means that the water temperature never sinks
to the same Tow level as the lancI masses.
NVall constructions having high heat storage
capacity; (i.e. high specific heat and density
characteristics) will dampen the effect of the
~naxin~um rate of heat gain (or Toss). As soon
as the ~naxin~un~ outside surface wall tem-
perature is reached. the surface begins to cool.
As tile outside wall continues to cool, the heat
flow that 1las started on its way through the
wall at the time the maximum surface tem-
perature was reached will be split into a quan-
tit~; that will flow out as well as in. This
cia~npens the amount of heat finally reaching
tile inside surface. The greater the heat stor-
age capacity the sneakier will be the instantane-
ous rate of heat flow to the interior. Obviously
this reduces the capacity size require(1 of the
cooling equipment.
What floes this mean to Duncan comfort?
The (la~npening effect of wall mass wit] reduce
the fluctuations of inside wall temperatures.
People living in frame houses frequently ex-
perience the necessity of setting the thern~o-
stat higher to compensate for a rapidly noosing
coIc! front which suddenly engulfs the house.
This sense of chilling is due to a sudden
fluctuation in insicle wall temperatures. In~-
~nediatel~, radiant heat is lost front the Duncan
boils; to the wall.
Another matter that is of importance is that
mass contributes to a lag in time of the heat
progressing through the wall. For example,
this Slav amount to six or eight hours for a
relatively heavy masonry wall, before the heat
which has accumulated during the day begins
to reach the interior later in the evening. But
in the n~eantin~e the external temperatures
hex e cTroppecT deciclecITy ancT you can then avail
OCR for page 55
yourself of nocturnal cooling by an attic fan.
Allis leas been a great benefit in Australia.
Their people have e~nployecl this n~etho<1 to
the fullest extent, almost eliminating tl~e
need for air conditioning systems in low-cost
blousing in that particular part of the globe.
In sugary, theory and experimental facts
to ciate show evidence that high heat storage
influences tI~ennal flow in the following ways.
T. Reduces the instantaneous rate of lariat gain
or loss. The initial size of the air condition-
ing or heating equipment may be reduced
by; as much as 25-50%.
7. Dampens variation of inside surface ten~-
peratures, thus contributing to greater co~n-
fort to the incliviclual clue to racliant ex-
cI~ange between Lois and his environment.
3. Delays the peak lint Toad reaching the in-
terior (time lag) which allows the use of
nocturnal cooling by attic fan for uncondi-
tionecT space or of favorable electrical rates
on air conditioners for conditionecT space.
T~_
HEORETICAL L)ISCUSSION
Tl~e factors that contribute to the ~nagni-
tude ancT variation of surface wall temperatures
are complex. Direct solar radiation plus rac:lia-
tion frown the atmosphere anc! terrestrial ob-
jects are tl~e initial sources of heat. The
amount of this latest that goes into the outside
wall surface is a function of the reflective
characteristics of the surface. Wl~ite or buff
surfaces may reflect 40-60~7o of energy received,
Wylie dark colors may absorb as much as 90~
and reflect only ~0~. (The building surfaces
the~seIves are sending out radiant energy to
their total environment to further con~plicate
the excl~ange.:
As a builcTing is surrounded by air, tem-
perature variation in the passing air masses
plus the speed of air movement affect the con-
vective transfer of heat into a building wail
surface. Surface texture characteristics influ-
er~ce this phenomenon.
The contained effects of solar radiation, air
temperature, and air velocity is frequently rep-
resented by the "Sol-Air Temperature" which
is the equivalent temperature at the weather
surface of the wall to give the saline heat flow
that actually takes place on to the surface due
to the above causes. It is similar to (but by
~nathe~natical definition not exactly) the ten~-
peratures of the outside wall surface. Outside
air temperatures may hare daily variations
ranging front ~ 7 to ~ ~ clegrees on the east
coast to 33 to 47 degrees in the Rocky Moun-
tain area. It is important to note that the air
temperature selclo~n exceecis a n~axin~u~n of
100 to TI0°F. whereas the Sol-Air ten~pera-
ture may have peaks ranging front ~ 30 to
~ 60 ° F clepending on the wall surface. Tl~e
daily variation in Sol-Air temperature may be
70°F on a north wall to /0°F for a west wall.
The flow of such a periodic heat cycle as
cTescribecl above through a builcTing wall is
ciepenclent on the physical parameter:
Thermal cliflusivitv (`x) a k
,
PA
Adhere k coefficient of thermal transmis
slon
p density
C specific heat
It is this physical property that is of signifi-
cance in discussing periodic heat flow as op-
posecl to k or U for steacly heat transfer. Un-
fortunately ~nathe~natical expressions relating
this property to heat flow are not in a form
suitable for office computation. However the
1950 edition of tile ASHAE Guicle approxi-
n~atec] the exact solution as follows:
q U ~ t,~-ti ~ + ~ U ~ te-tm ~
Revere q snag. rate of instantaneous heat
gain
where to= average Sol-Air temperature
te= Sol-Air temperature at a tinge earlier
by an amount equal to the time lag
55
OCR for page 56
ti average inside air temperature
g- a factor that ciepencis on the wall thick-
ness and orientation.
The tinge lag is the delay in the heat gain
clue to mass in passing through the wall. For
8" of brick this is theoretically 5.5 hours; for
2" of wood T.3 hours. The two wails have
about the sense U factor, yet the theoretical
n~axin~um rate of heat gain is 60: greater
through the wood for a west wall. The n~axi-
~nun~ heat gain would occur around 6:00
P.M. for the wooc! and 10:00 P.M. for the
brick.
Exact theoretical solutions taking into ac-
count mass effects have been achieved analyti-
cally by thermal circuit analysis or experi-
~nentally by electrical or hydraulic analogies.
These methods depend on the ~nathen~atical
parallel between electrical or fluid flow and
heat flow. These exact solutions substantiate
the above approximation and emphasize the
influence of the heat storage of interior walls
in re(lucing peak loacis.
ExPER~ExT~ DEs~oN
To determine with precision the influence
of heat storage on tile thennal performance of
cIav ~nasonrv the Structural CIav Products
Research Foundation undertook tile experi-
~nental stucly of eight wall constructions: 6
clay n~asonrv;, ~ wood frame, and ~ natal pane!
(See Figure ~ for details). The technique of
the experiment employed cubical huts (10' :;
10' in plan). Taxis pern~itted erecting 8' 2: 8'
HEAT FLOW THROUGH MASONRY
1 500 1 400
10" CAVITY WALL /__
8" TILE WALL \ \
6" TILE WALL \
8" B R IC K WALL
'\ 'A-
1 300
, ~ f RAME WALL
_ BRICK VENEER
_ TRAILER
_
METAL PANEL
f 6" BRICK WALL
FIGURE 1 Plot plan of test site showing ar-
ran~,ements of thermal huts.
56
panels in each wall of the but. oriented to the
four points of tile compass.
Tile purpose of adopting an experimental
study on such a relatively large phonological
scale was to obtain representati~eness hotly as
to flee panel construction and ~orI;n~ansl~ip
ancT as to tl~e statistical influences of weather
patterns. Smaller specimens were held not to
yield this effect. Prior to e~nbarI;ing on flee
program it was obvious that much fine theo-
retical work had been cone in the field of
periodic latest flow. However. for clay masonry,
the projection of this theoretical work into
practical results depen(led entirely on i(lealizecl
mathematical assumptions and on existing
laboratory cleter~nination of physical prop-
crties. It was felt that the combine(1 influence
of all variables subject to periodic weather
patterns could best be studiecl by full scale
huts. However elaborate the theory, it is no
better than tl~e experin~ental ~ ork on which it
is based.
The use of thermal huts for experimental
treat flow studies has been employed by several
Con~nonwealth Experin~ental Stations. Scan-
dinavian researchers have built then. In this
country vapor transmission studies at Penn
State and thermal circuit investigations at
UCLA are letdown to have used thermal huts.
The n~etho(ls of constructing the huts are
shown in Figure 7. Each hut rests on a rein-
forcecl concrete slalom. The walls are separated
front each other at the corners by plywoo(1
colun~ns filled with insulation. The walls were
erected on a 12" bed of rigid insulation (k-
.34~. The floors are covered with rigid insula-
tion board (K=.25) to a depth of 9". The
ceilings are insulated with 10" of loose fill in-
sulation covered by reflective insulation. The
attic space is vented and the roof surfaces are
painted alun~inun~. The construction is de-
signed to force the heat floss primarily through
the wall panels. Figure 3 show-e how access'
after the soZid waZZ panels are in place, is pro
OCR for page 57
FIGURE 2-View of huts prior to installation of
wall panels.
viclecT to the inside through~a trap door in the
roof.
Instrumentation includes thermocouples in
each wall (16 in eacl, face plus several ac~cii- or navies T°F ~ record of the inside ambient
air temperature is continuously, obtained. The
instrument sI~eiter contains watt hour meters
that measure total power consumption by each
lout and flow meters that measure the total
flow of water through the air conditioner.
Thennopiles measure the temperature gra-
~lient in the air conditioning water. It is ap-
parent frown this instrumentation that the
total heat flow into the huts may be checlce
against the heat re~nove(l. This has been done
and found to balance within 3 to 66,7G.
NVeather data obtained inclu(le outside
ambient air temperature, wind speed, wind
direction, amount of precipitation, and solar
radiation. Provision exists to measure air con-
ditioning condensate (latent heat ~ and hu-
~nidit~; inside each hut.
An over-all view of the test installation is
shown in Figure 5.
i. ~ ~..~..~.~ ~
~ . .... . ~
FIGURE 4 Instrument shelter housing 144
point longer.
FIGURE 3 Typical hut with access trap door
open.
tional ones of interest within the wall). Three
heat flow meters are placed on the inside of
each wall (ancT eventually on the outside).
Data front these instruments are recorclect (see
Figure 4 ~ in an instrument shelter which
houses a I14 point logger.
The tc~nperature within the huts is ~nain-
tained constant with the aid of 3 kw electric
heating cements and a sneaks 3~4 ton air con-
ditioner. A spiral type ther~noregulator ~nain-
tains temperature in the huts to within plus
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ .~ ~ ~ ~ ~ . ~ ~ ~ i. ~ ~ ~ ~.~.~ ~ ~ ~ ~ . ~ it. it.
FIGURE 5-Complete test installation.
57
OCR for page 58
TES T RESULTS
Since tile test project started in Sentencer
of 1955, only ciata for the winter season are
now available. The influence of heat capacity
during the winter season has not been studiecl
bv theoretical analysts for it has been assurnecl
J J
that the range of ciaily temperature variation
was greater in the sundrier than in the winter.
the incident solar racliation is greater in sun~-
~ner than in winter, and the difference be-
tween insicle and outside mean temperatures
is n~uch greater in the winter than the sum-
mer tending to mask the influence of tee ciaiTy
tenaperature range. Due to these consiclera
Building Ail
Brick Veneer (a
Building #2
10" Cavity (c )
Building #3
S" Solid (b)
Building #4
"SCRbrick'(b)
:3rlilding #>
8" Tile (c)
Building #6
6" Tile (c)
Building #7
Steel Panel (a)
Building #8
Wood Frame ~ a
Ma';. Teacup. °F
Min. Teacup. °F
Average Wind Nic1.
% Possible Sun
Precipitation Trace
tions the conv~ntior~al steady flow Sterna
properties were felt adequate for heating sea-
son calculations. Data presented below sug-
gest a re-exan~ination of this viewpoint.
Table ~ su~nn~arizes the experimentally ob-
tainec] Us factors cletern~ined uncler periodic
tl~er~nal flow clue to varying weather patterns.
This factor represents tile average heat Toss
through the walls of the thermal hut for the
period of stucly per clegree F temperature dif-
ference between average inside ancT outside
ambient air (see Table If.
Four three-day periods have been chosen as
typical results for n~icT-winter ancT earls; spring.
TABLE I
UV VALUES OBTAINED FROM THERMAL HUT PROGRAM
Jan. 10-13 Feb. 3-6 Us i\/Iar. 9-17 A,br. 77-30
.10!
.320
.936
9
.47,
.507
.767
.092
.297
.421
.452
.339
.394
.189
.1'T
38
78,
15 MPH 6 MPH
0-0-100 100-99-76
NOne
.117
.397
.491
.678
.186
.146
.408 .375
.42)
.1,0
( a ) NNiall constmction includes interior Lisle and insulation # ]
(b) Interior finish and insulation added between Feb. / and Liar. S. #a. =4
(c) Exposed masonry on interior, - I. ~5. -'6
58
.094 .096
.347
.183
.117
.397
.704
.167 .17)
.40&
.431
.439
.750
.12)
~9
14 MPH 14 RIPE
100-70-68 7 5-0-0
7.38~, Rain
.93/
775 .150
.179 .110
78
36
.47 3
OCR for page 59
A variety; of weather patterl-;~s is represented.
The period front Jan. 10-13 represents as near
a steacly state as was obtained during the
period of record: even here a 10°F range was
experiencecI. Feb. 3-6 was a period of high
temperature range, Tow wincT speecTs, ancT large
percent possible sunshine; therefore, cyclic in-
fluences shouicT be most pronounced cluring
this period. Tile period April 27-30 inclucTecT
mostly overcast skies witty consiclerable rain.
The Us factors are those calculatecT front
tee ASHAE Guide for steady state condition.
The one exception is the natal pane} which
value was obtained front the manufacturer
who reporter! the results of laboratory tests
on wall sections inclucTing through-the-war:!
metal ties.
The construction will not be clescribecl in
detail leers, but suffice it to say blat tile clay
masonry walls were all composed of red clay
units, lightly texturecT. The wall finishes used
consisted of conventional furring, blanket in-
sulation, ancT ciry wall techniques. The woos]
France but was coverer] with white ship-lap
sicling. The metal panel was a typical in-
Justrial type containing ~ ilk" of Fiberglas
insulation with a metal sheet interior finish.
Tl~e metal surface being galvanized was left
unpainted; this surface has darkened with age.
Generally speaking, there is a marked clif-
ference between the Us ant] Uv values. The
France and metal huts have Uv values above
Us; the clay masonry buts have values below.
While differences in color do have an effect,
it should be noted that the frame was white
and the metal was darkened galvanizecT, each
representing racliation extremes on both sides
of the reel brick color; yet both of these con-
structions having sn~all mass showed heat
Tosses greater uncler periodic heat flow than
predicted front steady state knowledge (10-
20G/G for France and 30-6070 for metal). The
clay n~asonr,v (lisplayed Us values that were
0-705 below tee Us values with a trend to
smaller differences occurring with the hollow
units and larger ctifl:erences with the solid
units.
A comparison between the brick veneer and
France is of interest since these two construc-
tions hac] nearly identical Us factors. Yet the
veneer experienced heat Tosses roughIv lL0~7O
less than caTculatecl, Whereas the France showed
15':0 snore. Maltese two constructions were near-
ly iclentical except the outside covering being
4" of red brick in the one anc] I" of white
wooc! siding in the other. The table below
shows for tile Feb. 3-6 period the daily Us
values for the north anc] south walls of the
two huts.
Us
UN North NVall
_/ ~
2/4
2/5 . . . . . . . . . . . . . . .
U>. Softly NVall
2/3
2/4
/ ~.
Brick Wood
Veneer Fit ame
.112 .110
.118 .135
.119 .148
.12S .131
.069 .096
.067 .11 3
.063 .089
Tllese data, typical of other perio(ls. show
that even on tile north wall (where color dif-
ferences are n~inin~ized) the veneer values are
much less than the frame values. The low Us
values of the soutl1 wall are due to the solar
radiation received during the day. The data;
also point out tile difficulty of choosing an
arbitrary U factor to be representative of Motif
orientation and periodic effects. Tllose designs
based on U factors carried to tile third decimal
place suggest an accuracy not warranted.
A comparison between the "SCR brick" (a
6" througll-the-wall clay unit) and the metal
louts is worth noting. Tl~e insulated values
of these walls are roughly the same (.175 and
. 150, respectively) . The Uv for the "SCR
brick" is on the average 157 under tile Us
value whereas flee Uv for the metal is about
507 above. On this basis. if the two waZZs had
59
OCR for page 60
identical U factors, 55C:o more heat would be
lost through the metal pane, than the "SCR
brick." Presumably these differences are due
to mass. The experimental determination of
Us for the metal panel is reported to have
taken into account through-the-wall ties. The
darkened thetas surface should have had the
advantage in receiving solar radiation to re-
cluce treat loss.
Thought not studied in as n~ucl~ detail as
the U factors above, the maxin~un~ rates of
heat loss shown for the brick veneer and
frame during the Feb. 3-6 period are:
Brick Veneer Wood Frame
btu/ fir. btu/ hr.
North Wall
2/3
2/4
2/5
South Wall
2/3 . . .
274 . ... ...
2/5
60
500
450
400
400
350
300
600
500
350
600
500
350
Thus tile demands on the capacity of tile
heating source were 20WG less in the case of
the brick veneer.
SUMMARY
The results obtained thus far in talc Floral
hut program were primarily for the winter
season. Contrary to orthodox assumption,
periodic heat flow was shown to have a signifi-
cant influence on heat losses. Under the
periodic heat flow of actual winter weather
patterns wall constructions having low mass,
such as France and metal panels, were shown
to have total heat Tosses significantly greater
than front steady state calculations (ranging
front 10-20~7o for the France and front 30-40%
for the metal). For walls having high mass.
such as clay masonry, the total heat losses were
less than front a steady state calculation (rang-
ing front 0-20~7O ~ . The precise extent to which
mass (both density ant] specific heat) affect
this result may await future detailed stucly of
all the physical parameters concerned.
OCR for page 61
Ceramic Veneer Panelizing
M R . F ~ s HE R: One of the fine things
about these BuiZ6ing Research Institute Con-
ferences of this kind is that a wide variety of
viewpoints is re,~resented. In contrast to the
viewpoint of Err. Monk for the engineers,
we have an industriaZ viewpoint expressed by
Mr. Barnes who wiZZ speak on ceramic Veneer
pane7lizing.
EVERY alert November of the buiTcling industry
has, ~ awn sure, noted with great interest the
trend in recent months toward the extensive
use of curtain wall construction. It has become
so well known and so widely used that no
definition at this time is requirecl. Mender
manufacturers of the Architectural Terra
Cotta Institute have noted this trend and
recognize the obvious merits of curtain wall
construction.
Albert E. Barnes
Cladding, McBean & Company
San Francisco, Calif.
In ad`lition to his 29-year connection with
GZadding, McBean ~ Company as manager
of architectural products promotion, Albert E.
Barnes is also Secretary of the Architectural
Terra Cotta Institute, a past president of the
Southern California Chapter of the Producers
Council, and a member of the Construction
Specifications Institute.
As has so often been pointed out, curtain
wall design elin~inates the need of a back-up
wall, thereby reducing the required wall thick-
ness and reducing the weight of the exterior
wall. As a matter of fact, there has been a
trencT toward thinner mason curtain walls for
a number of years and some of the largest
and finest recent buildings on the Pacific
Coast have had exterior masonry non-Toad
bearing walls of S" thickness rather than the
61
OCR for page 84
to existing wood or fiber sheathing with spe-
cial metal clips to hold it in place. The joints
are filled with a real mortar applied through
a special pressure gun which we have devel-
opecT. Special L-shaped corner units are en~-
ployec} so that a genuine brick appearance is
achieved. Economic studies inclicate that it
can be applied in place and be directly cornpet-
itive with many types of residing materials on
the market. It also has a very definite place for
interior redecoration of existing buildings since
it will not require the strengthening of walls or
floors to carry its weight. It is currently being
test n~arketec! in the Colun~bus, Ohio, area to
learn marketing techniques and facts prior to
its national introduction to the builcting indus-
try. If this new product reaches 10% of its po-
tential market it will provide a 58 nonillion clol-
lar annual market for our Industry in a ren~od-
eling field in which it has never hac] a major
foothold.
At the present time in another of our major
markets it has been established, and ~ ant sure
it will be confirmed! tomorrow, that masonry
curtain walls are one of the n~ost economic
forms of construction available on the market
today despite all cIain~s to the contrary by the
pane] wall people. Even in the matter of speed
of building enclosure, the proper size mason
crew for a job can still keep up with the other
trades that must complete their work in the
over-all construction schecluTe. The one dubi-
ous advantage that panel walls today might
have lies in their reducer! thickness. In order to
protect our future economic position in this
field we have been carrying on considerable
long-range work in precast panelized wall sec-
tions for exterior curtain wall applications.
NVe have developed an extremely fast setting
cement grout which wit] enable us to produce
such panels without large nooks investments.
In its exterior applications, such panels are
two and one-half inches thick, and reinforce(l
to carry tile required wine} anti other structural
84
loads. Only two sizes would be needed in any
specific building. It appears that these panels
can be produced at a plant price of $~.00 per
square foot an(l installed with lath ant! plaster
interior for another $~.00 per square foot.
We have also produced a structural ceramic
glazed clay tile unit four inches thick that has
a sound absorption of 60N, and a sound trans-
emission loss of 47 db. unplastered and 54 db.
plastere(1 on the back sicle. Production equip-
~nent for this tile is currently being (developed.
A process for the production of economic
lightweight clay units has also been developecI,
and is currently being refiners on a pilot plant
scale. It wit! permit a reduction of weight for
structural brick an(1 tile units of 40GNo in addi-
tion to that weight saved through coring. In
other words, a current five pound brick wouic!
weigh three pounces and the eight pound "SCR
brick" would weigh less than five pounds. This
lightweight process provides sealed cells, and
the water absorption of such units is not appre-
ciably higher than current clay bodies. Our
process, which we believe to be unique, will
permit the production of such units by nearly
every one of our November manufacturers de-
spite the great variation in clay properties that
exists in our industry. It will permit a greater
control of unit size, and will make grinding to
exact size an economic possibility. Best of all,
it can be pro(luced with the existing facilities
of our industry without requiring that they be
obsoleted or discarclec] before this development
can be offered to the construction industry.
Another important current phase of activity
of the Foundation involves physical research
to learn new facts about the behavior of clay
masonry walls front a thern~al transmission
basis. ~ believe we have the most elaborate
buil(ling thorns research program uncler way
in the country. We have built six test buildings
with six different types of masonry wall con-
struction, ant} one identical builcling with
metal pane} walls and another iclentical build
OCR for page 85
ing with wood France walls. Each building is
heater! anc] eoolecT as desired by a special air
conditioner and electrical heating device. Hun-
drecis of thermocouples and dozens of heat
flow meters are employecT plus a very elaborate
control ancT instrumentation builcling. These
tests are already showing that the thermal ea-
paeity of masonry walls can be a deeicled factor
in reclueing the initial size ancT cost of heating
and cooling plants. They are definitely show-
ing that the U-faetor of a wall is not necessarily
the only factor that will cletern~ine the thorns
perforn~anee in a building of a given wall eon-
struetion. The first public progress report on
the results of this research has been given to
this conference earlier tociay by Mr. C. B.
:Monk.
Fundan~ental research into mortars has be-
gun to show real progress. Certain cement
eon~binations currently under study are devel-
oping ultimate bond strengths in excess of 700
psi, instead of the name usual 50 psi. It is
still a mortar that can be handIec! with the
trowel. Funcia~nental research into efflores-
eenee and greenstaining is cleveloping knowI-
edge that is aIreacly being en~ployed in some of
our plants to recluee this problem in wall ap-
pearanee. Tmprovec] methods of cleaning n~or-
tar stains from masonry have also been cle-
veloped.
In connection with effloreseenee, ~ would
like to eall the following facts to your atten-
tion. Sonnetizes on a given building, arehi-
teets, contractors ant! owners fins! effloreseenee
on eIay units which in the past have never giv-
en then any trouble. It must be remembered
that effloreseenee means that there was water
within the wall to carry soluble salts to the sur-
faee. Without such water, regardless of where
it originates, effloreseenee cannot oeeur. We
have also established that even if the brick is
absolutely effloreseenee free, serious amounts
of effloreseenee can result if there are soluble
salts in either the mortar or the back-up ma
sonry materials. It has also been established
that even if the bricklaying workmanship is
perfect so that water cannot enter the exterior
face of the wall, effloreseenee can still occur if
proper flashings have not been installed at crit-
ical points in the building or if moisture vapor
is not prevented by suitable vapor barriers front
entering the wall from the interior side.
A large amount of our work in the past and
present involves architectural research studies.
For example, facing tile shapes are being an-
alyzed with a view to a sin~plification of shapes
to reduce plant production and inventory prob-
len~s as well as the design of such walls by the
architect. It is believed that this study will per-
~nit more rapid deliveries of facing tile to the
public ant! will make estimating of facing tile
a much simpler procedure.
Architecturally and structurally we have also
stucliecT school construction requirements and
costs. There has been a substantial amount of
publicity given to purported] savings in school
construction costs by means of prefabrication
of buildings constructed of either metal or
wood. Widespread claims have been made
that such schools can be erectec] for the school
boars! at classroom costs of 15 to 20 thousand
dollars. This has been coupled with the claim
that this cost is one-third or less of the usual
typical masonry school which has been stated
to be as high as 50 thousand dollars a cIass-
roon~. Our school cost studies have shown the
"per classroom cost figure" to be completely
misleading. On a recent public platform with
Nile one of the prefabricated school suppliers
stated that they had just completed a six cIass-
room school for $120,000, or $30,000 per cIass-
room. The square foot cost of his buildings
however, turned out to be more than AS per
square foot of space. There are many, many
masonry schools being built today in all parts
of the country for costs of 10 to 12 clolIars per
square foot. Further, they provide the school
board with yearly savings in the form of low
85
OCR for page 86
maintenance and operating costs, real fire pro-
tection for the students and the wealth of color
ancT architectural form that architects can so
well fit to the local site ancT surroundings.
In a (lesire to provide a simplified design for
even lower cost masonry schools we have also
developecl a concept of load bearing interior
wall construction that, in the Chicago area, can
pennit econon~ical masonry school construc-
tion at an estin~atecT $8.35 per square foot in-
clucTing the mechanical services. ~ sin~ilar cost
study in Texas employing this concept yielcled
an estimated cost of $7.14 per square foot.
However, contracts for three schools of this
type leave since been let in Texas at square foot
costs of $6.7l, $6.86 and $7.25, respectively.
This is dramatic proof that real utilization of
the structural properties of masonry combined
with the attendant savings in the roof and
framing structure can result in a balanced de
. , .
sign or maxllnum economy.
A recent phase of our work that has been
extremely interesting is a series of high explo-
sive shock loading tests of various masonry
walls. In the final test, ~ walls were simulta-
neously tested in an octagon test-fixture ap-
proximately 30 feet in dian~eter. Four of the
walls were n~ounted as vertical beans, 9 x 10
feet in size. These were: ~ a ~ standard S"
brick and block construction; (b) S" rein-
forced lightweight concrete block; (c) 9" re-
inforcec] grouted brick wall with the same
amount of steed as in "b"; (cT) 9" reinforced
grouter] brick wall with twice the steel of "b"
and "c". The other four walls were testecI as
horizontal beans with end restraint against
pilaster-type piers to develop "arching" action.
These walls were 10 x 9 feet in size. They
were: ~ e ~ S" brick wall ~ unreinforced ); ~ f ~
12" brick wall (unreinforcecl); (g) 9" rein-
forced grouted brick wall with the same steel
as "b" and "c"; (h ) 6" "SCR brick" wall with
~ pencil rods in every other horizontal mortar
joint.
86
Forty-five pounds of high explosive were
detonated within the octagon, developing a
peak surface pressure of 140 psi for 3 miTTi-
seconds. This is in excess of the energy im-
puIse sustained at 4700 feet front ground zero
during Operation Cue's atomic building test
in 1955. At that time, wall "a" in a two-story
home failed, and wall "b" in a one-story
structure withstood the blast. In our test,
these two walls were employed as control speci-
n~ens to provide direct comparison with Opera-
tion Cue performance.
In our test, wall "a" was co~npleteliy de-
n~olished as at Operation Cue and wall "b",
which survived Operation Cue, was completely
destroyed. All six of the other walls stayed in-
tact and were all structuraZZy sound after the
tests. This dramatically illustrates the fact that
economical brick walls can be designed to
withstand the tremendous lateral pressures
generated in atomic blasts, earthquakes, hurri-
canes and tornadoes. The engineering design
criteria developed in this program are being
assembled into a "hand-book for blast resistant
design" to be released to the architectural and
engineering profession this fall.
We began our research effort in 1950 be
J
employing the technical and industrial re-
search facilities and staff of Armour Research
Foundation of Illinois Institute of Technology.
This was supplemented by contractual arrange-
~nents for our architectural research witl1 tile
architectural firm of Howard T. Fisher Nz Asso-
ciates of Chicago. In ~ 95 ~ we leases] labora-
tory space of our own to supplement the con-
cract work, and began to acquire our own staff
and equipment as our objectives and programs
began to develop and nature.
In 1954, our n~anagen~ent demonstrated its
faith in its research effort by authorizing the
establishment and construction of a new na-
tional Research Center for our industry. It
was built on a 15-acre site 40 unites west of
OCR for page 87
Chicago in Geneva, Illinois, and occupied last
fall. \Vithin the engineering section of this
buiTcling full size two-story tonnes, or two-story
prototypes of a n~ulti-stor,v builcling, can be
erected to stucly engineering ancT construction
techniques anc] to develop short cuts that will
result in lower construction costs. Space Las
also been provided for the establishn~ent of
pilot plant production lines such as for the
automatic packaging machine and for tee pilot
production of pre-cast wall sections. Facilities
have been provided for engineering stucly ancl
testing of full size wall sections for water
penneabilit~i ancT for compressive, transverse
and racking strength. Complete ceramic re-
search facilities of both a funcian~ental and
production nature Lave been installecI. En-
gineering ancT architectural laboratories have
been provicled. Sufficient :lanc] is available at
the site to permit tile outdoor erection of full
size prototype structures to test builcling tecL
niques and materials clevelopecl in the labora-
tor~;.
For speciaTizec] personnel or equipment, or
for certain projects of short duration, we still
intend to employ tile services of establisllec!
research organizations.
The Foundation with its adequate reserves,
new facilities anc] trainee] stab, is cleclicated
to the in~prove~nent of masonry structures
and to the development of more economical
ways in WIliCI1 to buiT(1 tiled.
Research leas given our industry a new Took
into its future a new confidence in that future
a future of better present products, and with
new products for new markets. It has en-
couragecl the Industry to increase its capacity
by snore titan 20: in 1955 an(l 1956. Truly,
research is enlarging tile frontiers for brick and
tile and we are confident that our inclustrv will
continue to maintain its pre-en~inent position
in the construction industry, Motif today and
to~norro~7.
87
OCR for page 88
OCR for page 89
Discussion
M R . F ~ s H E R: Our first question is di-
rected to Mr. Howe: With expansion and
contraction in New England temperature
ranges, what is the maximum size sheet recom-
~nended for n~arble veneer if maintenance of
joints is desired?
M R . H o sv E: T think we said this ~orn
ing that the n~axin~un~ size is what the quarry
would produce, but it would vary some on the
quarry itself as to size. But I'cI think the
naximun~ panels would be somewhere in the
neighborhood of six to seven feet long and
three to four feet high. Although the other
clay we had one ~ 5-foot square.
M R . F ~ s H E R: Mr. Taylor, what provi-
sion was Inane in your blast tests to com-
pensate for the pressure relief afforded] by the
failure of walls in determining the resistance
to the blast?
M R . T A Y ~ O R: Tile velocity of the mass
propagation and the short duration of tile total
blast of only three milliseconds. Our pressure
measurements incTicated that there was no
cti~ninution of an;; specific wall, because two
walls went out.
M R . F ~ s H E R: Here is another question
to Mr. Howe: Is any serious work being
clone toward structural applications of natural
stones, such as prestressed stone assemblages,
utilizing new cutting methods and high
strength, low creep characteristics of stone?
M R . H o w E: ~ don't believe so.
MR . FISHER: In these panels Mr.
Taylor just spoke of, they are using the brick
structurally there. ~ think they first asked that
question, wondering if any similar work was
being (lone in the marble field.
MR. HOWE: I'm not on the research
committee of our institute, but ~ have not
heard that they are starting that as yet.
M R. F ~ s H E R: Here is a question for Mr.
Monk. If you had used a porcelain enameled
pane] instead of a galvanized one, would your
results have been any different?
MR . M ONK: The only difference wouIcl
have been in the color. And you will note that
89
OCR for page 90
~ e~phasizecT, but ~ clicIn't have a chance to
explain it, that the France Lut was white. The
metal hut happened to change to a ciark color,
so we hacT two extremes of color so far as mass
was concerned. The enamel, of course, wouIc]
be somewhere between these two extremes.
The difference probabiv wouicT be onIv in
J J
color, and therefore it wouicT be someplace
between ~ ~ per cent ancT 50 per cent heat Toss
in excess of what you can expect with Horns
U factors.
~ R. F ~ s ~ E R: There is a general question
to all of the technical speakers this afternoon.
If the jointing material for masonry is more
important than the masonry n~ateriaT itself,
whv taken has this important factor of n~asonrv
J J
work not receiver] more discussion by techni-
cal speakers of this conference?
Before passing that question on, ~ wouIcl
like to sac- it is no own ingression that a
J J
considerable portion has clealt with the rela-
tionship to the jointing between panels.
Who wouIc] care to comment? Mr. Taylor?
\{ R. T A Y ~ O R: Front nay point of view,
I'c! say it takes approximately 75 per cent of our
total research, both in the prefabricated panels
and research having to do with stanciard type
units. AncT we have work, as ~ mentioned,
where we have achieved 200 psi bond strength
compared to '0 psi. We also have evaTuatecT
mortars. It's a very important thing, because
the strength of a clay wall is no better than
that of its weakest component, which in this
case happens to be mortar. And it is essential,
to get the best results, that the design of our
inclustr,nT's products follow the kinds of speci-
fication we know will really give good per
for~nance.
M R. F ~ s H E R: WOUI] anv~oUv else like
, ,
to comment on that last question? Mr. Mc-
Knight?
90
M a. M e K N ~ G H T : T think, Mr. Fisher,
along with joining mortar tilers has been quite
a revolution in the mastic industry in tee last
year with some new discoveries in mastics,
which we Lave usec! in broadening our scope
in joining these panels.
M R. F ~ s H E R: How permanent are tee
penetrating stains to outdoor exposure? Mr.
McKnigllt.
M R. M e K N ~ G T-T T: NVe have run some
of the most elaborate barometer tests possible
with the latest equipment. NVe know (lefinite-
Ty that we can penetrate with special spraying
cquip~nent the stain to a clepth of a quarter of
an inch. Tllat is consiclrecT an average because
we clo have some variance of natural n~aterial.
Groin all indications frown the technicians and
engineers, we can say, for all reasonable appli-
cations, it is good for 15 years.
M R. F ~ s ~ E R: Mr. Barnes, can satisfactory
lateral (reflection of one story with respect to
the next be per~nittecl, say /-inch per story;,
with safety to the panels? ~ assume the ques-
tioner has in noting! the wind stresses on the
building possibly cracking the terra cotta.
M R. B A R N ~ S: We were faced with that
on a recent project in Oakland, where it was ex-
pressed in IS of an inch drift per story. what
depends entirely on the connection and it is
quite practical, and the material itself is very
adaptable to the proper connection for that.
M R. F ~ s H E R: What is the effect of stack
bond versus running bond in RBM? Mr.
Dickey isn't on our pane] at the moment.
Would he care to convenient on that front
the floor? Someone said this morning they
thought it would not have too much effect
on the strength.
M R. D ~ c ~ E Y: Yes. Normally the engi-
neers just don't like to fool; at tile stack boncI.
It (loesn't look as strong, lent the tests show
OCR for page 91
that we shouldn't Took clown at stack bond,
that we should be snore optimistic. Tests
showed that reinforced stack bone! wouIcI be
just as good as your design valuation but that
your unreinforced running bond would be
eight tinges as good, which wouIcT indicate an
extremely 1ligl1 factor of safety in masonry.
M R. F ~ s ~ E R: What is the relative cost
of cut stone and clay brick-say a cost per cubic
foot? What is the ~nini~nu~ thickness of stone
paneling? Mr. McKnigllt?
M R. ~ C K N ~ G H I: Well, Mr. Fishier,
there are several things teat are contingent
here. For one thing, freight rates, location of
the job. But for the roost part, you have the
source of brick near every metropolitan area
in the country;. Whereas limestone is very
limited as to its location in areas.
With regard to that last question on tl~ick-
ness of our panels, today we are working on
two incises. They have been adapted ancT are
being applier! now to the two-inch thickness.
We flack it clown to one inch, but at the present
tinge our specifications call for the two-inch
thickness.
MR. Fisher: Mr. Taylor and Mr.
Monk, Las any research been done on tile
prospect of reducing tee thickness of joints
on S.G.F.T. I'n~ not sure just what this
means without grinding on the job, especially
clouble-faced partitions?
Can you continent on the general problem,
Mr. Taylor, of joint thickness ant] flow you
look upon it in the future research?
MR. TAYL OR: It is a very important
problem, and the control of clay to an exact
size is often difficult in solve of our clay procT-
ucts. But in terms of some cloul~le-faced parti-
tions, they are available in some places in this
country in two colors. The surfaces are glazecT.
Sucks units are available in certain tripes of
manufacture units tociay. We do fee] that
when we leave a lightweight aggregate that we
. .
wit] cone even closer to having that sense
control size available in all of our clay; products.
M R. F ~ s H E R: How creep floes the color
stain penetrate limestone, and can it be ap-
plie(1 on tile job? Mr. McKnight?
M R. :~! C K N ~ G H T: ~ think, Mr. Fisher,
that ~ answered that question a minute ago
when ~ said as an average the stain can now
penetrate to a point of 3/16 of an inch to a
quarter of an inch, according to the density
of a product. You have to understand tllat,
witty tile process of taxis special spraying equip-
n~ent, you can put the stain into the stone
with an absorption point where it will last for
~ 5 or 20 years. But you also have to take into
consideration that stone is a natural product
anc! will vary maybe son~etin~es within four
or five feet running length. But ~ ant speaking
now of tile average, and we wit] say it is 3/16
of an inch as the average and is good without
any noticeable fading for 15 years.
M R. ~ ~ s H E R: What are the limitations
in the use of I~ighly-colorecl and figured ~nar-
bles for very thin stabs? Mr. Ilowe?
M R. H 0 w E: Well, of course up to this
tilde we have used generally what we call the
sound Garlic. But stuclics are going on, ancT
T awn sure in the clays to come we wit] finch
ways to perfect nature's shortcomings to use
the colorcc! marble very successfully.
M R. F ~ s H E R: Tllis is in connection
with granite ancT marble research. How are
the marble panels attached to tile buiTcling
frame to prevent moisture pcnctration, to per-
~nit structural cleflection, but to be safe in
earthquakes? Mr. Howe?
Ma. HOWE: ~ clon't believe that ~ will
attempt to answer that, sir. Of course on the
west coast the present requirement is that tile
n~arble panel, as an orclinar-y veneer, is joined
91
OCR for page 92
to the structural wall. I'm not experienced
with this earthquake question.
M R. F ~ s H E R: Mr. Barnes, what type of
material is used for the intermediate or false
joints in your panel? How was a satisfactory
bond effected?
MR. BARNES: The jointing mortar, ~
presume, is what is referred to, between the
various elements of ceramic veneer in the one
panel; ant] that is a rather dense jointing
mortar application, approximately one to
three, with one quarter part lime and a small
amount of ammonium stearate added.
What was the other part of that question?
MR. F~sHER: Well, it's justthe same
question, how is the satisfactory bond effected?
assume the material achieves that.
M R. B A R N E s: Yes, it will. if tile bone]
material is well dampened, there is no problem
on the bond.
M R. F ~ s H E R: Mr. McKnight, are these
penetrating stains inorganic colors?
M R. M c K N ~ G H T : Yes, they are. These
stains have been cleveloped not through our
own laboratory anc] engineering abilities or
facilities, but we have gone to some of the
major chemical companies throughout the
United States, told them what we were after,
told them what the potential was, and they
in turn worked with us in this coordinated
effort in developing the stain.
As a matter of fact, soda`; has been the first
tinge a member of the Institute has released
then; and the specifications preparer! for them
will be distributed to the construction indus-
try in the near future.
M R . F ~ s I! E R: Mr. Taylor, your insti-
tute has in the past frowned on silicones as a
surface water-repellent treatment for brick,
92
etc., presumably because of suppression of
efflorescence and hence promotion of spelling.
T.s the Institute still committe.`l In that nosi
M R. TA Y ~ O R: ~ have had experience
with silicones and a knowlecige of them for a
very long tinge. In fact one of my best per-
sonal friends, probably, is the inventor and
original developer of silicones; and ]: ant the
first to admit that they wit} stop penetration
of water through certain size pores and with a
breathing action remaining. But they will not
span, necessarily, cracks of more than a certain
size, nor will they close up joint mortar cracked
by erosion or other types of defects, unless
the wall is first tuckpointed. I spoke about
some of the danger of efflorescence due to
interior water entering the wall from other
sources. We leave firm proof and we have a
building to point to in which silicone was put
on it to cure the leaking condition that existed,
without first putting the building into good
masonry repair. And more than half the brick
in that building have spelled. There are slabs
a half-incl~ thick around the base of the build-
ing. And silicone applied properly; wiT1 do a
good job with masonry where special condi-
tions make it necessary to use it. But T would
hate to be the guy that put silicones on a
building, made the decision to do it, and have
to pick up the tab for rebuilding the building.
And that is why we take that position. At one
tinge our industry even considered supplying
and furnishing contractors with silicone that
we'd mix in our own plants. But we had to
abandon that. It happens that, when soluble
salts in the brick or mortar are dissolved, that
solution of salt moves to the surface like
normal water, only it is carrying efflorescence
salts. When it reaches the silicone, it can moire
no further, so evaporation of the liquid takes
place at this point, because the surface is
porous and crystal pressure develops which
OCR for page 93
can be as much as 4,000 or 5,000 psi locally
or cause splitting of the brick itself.
M R . F ~ s H E R: Mr. McKnight, do your
through-wall pane} tests indicate that the use
of Tectun~ insulation board, as the back-up
for your exterior stone panels, afforcIs sufficient
water resistance to repel driving water surface
penetration front rain storms?
MR. MeK~cHT: We have run tests on
this natural stone facing utilizing a number of
welI-known insulating n~aterials. The use of
Tectun~ for a complete through-wall panel
is, however, still in the testing stage. We have
not as vet officialIv released such a wall for
J J
recommended use, but anticipate cloing so in
the very near future.
My picture of a through-wall stone faced
composite was not Tectun~ but fount glass
nanufacturecT by Pittsburgh Corning Corpora-
tion.
The many tests we have run for thin natural
stone wall panels in combination with insula-
tion n~eclia have successfully passed our labora-
tory requirements. The U factor has been
highly satisfactory. It should be noted that
the insulation part of the unit assumes no
structural function. It is, rather, a ~nediun~
to which natural stone facing or possibly a
natural aggregate composite can be bonded.
The other type of pane] which we have re
leased will probably mostly be used in the cona-
mercial field. On this panel we apply several
thin stone pieces to a single sheet of Tectun~.
In this manner we can construct a thin,
stone-faced panel of aIn~ost any reasonable
size. We are negating use of this development
on a large shopping center at Indianapolis.
The panels we use there are lL0' high and 30"
wide ant} consist of 2" of limestone n~echani-
cally fastened to 7" of Tectun~. The masons
working with this new material for the first
tinge anywhere achieve a setting rate of ap-
proximately 1,700 square feet per day. This is
not a complete through-wall. But the con~-
bination of natural stone and insulation re-
duces the wall weight in addition to providing
a high insulation value, low cost, and sheerly
erection. The panels are anchored into the
back-up of structural steel with strap anchors
and clowels. This type of construction is highly
practical ant] may be adapted to many (resigns.
M R. S I L L I N G: ~ think one of the most
interesting things about these sessions that I
have always found tremendously impressive,
and that has impressed people front other
countries who visit technical sessions in Ameri-
ca, is to find the wheels within wheels. And
while they may respectively rub abrasively
against each other, T invite you to remember
that they also do interlock; and T think that
is a very interesting commentary on industry
and private enterprise in America.
93
OCR for page 94
Representative terms from entire chapter:
natural stone
