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Harpeth Hall School (1951 - ).

The Architect & engineer of California and the Pacific Coast (Volume v.25 (May-July 1911)) online

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have sufficient wearing body has been the aim of the engineer, contractor,
consumer and manufacturer. Thus w-e will consider a few of the essential
factors :

1st. Materials should contain a vehicle and pigment working in har-
mony with the conditions upon the surface.

2nd. Thev should contain an acid and alkali sunproof color and pig-
ment.

3rd. They should be sufficiently hea^'}• to fill the surface voids and stop
suction.

4th. They should have a sufficiently hard wearing surface to allow
successive coats, without further treatment of the surface.

5th. Thev should produce a finish sufficiently close to the texture and
originality of the surface.

Treatments

Treatments of concrete surfaces are divided into two divisions as
follows :

The shallow or superficial method or treatment is a filling of the voids
near the surface without discoloration. It is one that was much sought after
in the carlv stages of concrete work, especially on concrete blocks, etc.

Although the monolithic type of construction has gained more favor
in larger construction, the mechanical and chemical treatments of surfaces,
as outlined, are the surfaces most in need of a shallow or superficial treat-
ment.

Cement bricks, blocks, cast stone are also surfaces that need a light
treatment.

The physical or external method or treatment is a coating of natural
materials as a prevention of contact between the elements and the construc-
tion. The treatment should be defined imder two divisions:



The Architect and Engineer 89

1st. Damp-proofing and decorative, without complete obliteration of
the texture of the surface.

2nd. Water-proofing only, without the decorative feature, and com-
plete obliteration of the texture of the surface.

Under the first division you have a combination of results, against the
mechanical and chemical disintegration of the surfaces, as defined for ex-
terior surfaces. The operation should be twofold in its purpose : Damp-
proofing and decorative in one operation, without destroying the texture
of the surface.

Under the second division comes the subject of water-proofing (defined
by Webster as proof against penetration), which may mean everything or
anything — and we are sure the word has been handled improperly as to
its meaning, because of our undying enthusiasm on the subject — although
it may only mean damp-proofing, instead of water-proofing.

\\'ater-proofing is an engineering problem of much discussion pro and
con and does not enter into the subject of concrete surface treatment.

The following essentials should be strictly adhered to to insure results
for the surfacing of concrete:

All exterior or interior surfaces must be free from loose scales, sand,
grit, grease, oil or other foreign matter.

Surfaces can be freed of such materials by either scraping, wire-brush-
ing, or scrubbing with carborundum brick.

No muriatic acid or other acid treatment should be used, unless the
surface is thoroughly neutralized by water or a light alkaline solution.

Cjreen surfaces should be treated with a thin coat of surfacing materials
to aid the neutralization of the free lime, and fill the voids u])on the surface.

After the first coat is applied, evaporated patches should be re-coated
to insure evenness on the future coats.

All surfaces should be dry and free from moisture to give perfect
adhesion.

Exterior surfaces^ of buildings should be protected from rain or heat
while drying.

Physical or External Treatment

The figures, including the cleaning and preparing the surface under
ordinary conditions on two-coat work are generally estimated at 25c to 40c
a square yard.

The shallow or superficial method or treatment on coating two coats
costs about one-third to one-half per square j-ard less than the superficial
or external treatments, depending upon conditions.

The operator must be careful of the first or priming coats as they are
the foundations for a perfect bond and neutralization of the surface for suc-
cessive coats.

The operator should produce a surface te.xture without destroying the
originality of the surface.

No surface is free from dirt and foreign matter and it requires the re-
moval of such substances either by wire brushing or a light acid treatment to
remove stained portions in order to secure a firm bond and penetrating
quality to the surface.

In conclusion, I have endeavored to lay before you a few of the various
methods for surfacing concrete and their treatment for a decorative struc-
ture.



90 The Architect and Engineer

Schedule of Charges for Chicago Architects

THE following schedule of minimum charges and professional practice of
architects has been recommended by the Chicago Architects' Business
Association :

1. The architect's professional services consist of the necessary conferences,
the preparation of preliminary studies, working drawings, specifications, large
scale and full size detail drawings, and of the general direction and supervision
of the work, for which, except as hereinafter mentioned, the minimum charge,
based upon the total cost of the work complete, is 6 per cent.

2. On residential work, on alterations to existing buildings or monu-
ments, furniture, decorative and cabinet work and landscape architecture, it
is proper to make a higher charge than above indicated.

3. The architect is entitled to compensation for articles purchased under
his direction, even thoug'n not designed by him.

4. If an operation is conducted under a general contract, it is proper to
charge a special fee in addition to the charges mentioned elsewhere in this
schedule.

5. Where the architect is not otherwise retained, consultation fees for
professional services are to be paid in proportion to the importance of the
questions involved and services rendered.

6. Where heating, ventilating, mechanical, structural, electrical and san-
itary problems are of such a nature as to require the services of a specialist,
the owner is to pay for such services in addition to the architect's regular com-
mission. Chemical and mechanical tests and surveys, when required, are to
be paid for by the owner.

7. Necessary traveling expenses are to be paid by the owner.

8. If, after a definite scheme has been approved, changes in drawings,
specifications or other documents are required by the owner; or if the archi-
tect be put to extra labor or expense by the delinquency or insolvency of a
contractor, the architect shall be paid for such additional services and expense.

9. The architect's entire fee is itemized and proportionate payments on
account are due to the architect, as the following items are completed :

Preliminary studies, .2 (two-tenths).

General drawings, .2 (two-tenths).

Specifications, .1 (one-tenth).

Scale and full size details, .2 (two-tenths).

General supervision of the work, .3 (three-tenths).

10. Items of service are comprehended as follows :

(a) Preliminary Studies consist of the necessary conferences, inspec-
tions, studies and sketches modified and remodified to determine the client's
problem and illustrate a satisfactory general solution of same, both as to plan
and elevation. Illustrative sketches for this purpose need not be to accurate
scale, but should be approximately correct as to general dimensions and pro-
portion.

(b) General Drawings include figured scale plans of the various stories,
elevations of all the fronts, such general vertical sections as may be necessary
to elucidate the design, and such detail, drawn to still larger scale as, with
the assistance of printed notes, and of the accompanying specifications, may
make the whole scheme clearly evident to the mind of the competent builder
and give him a full and complete apprehension of all the structure conditions



The Architect and fliii^iiieer 91

as they affect the \ital questions of (lualily and (|naiilily of materials, of
character of wnrkmanshii), and of cost.

(c) Specifications consist of a supplementary statement in words of at
least all those items of information regarding a proposed building which are
not set forth in the drawings.

(d) Detailed Drawings include all the necessary drawings required for
the use of the builders, to enable them to so provide and shape their material
that it may be adjusted to its proper place or function in the building with
the least delay, and the smallest chance for errors and misfits. If not pre-
pared until after the contract for the building is let they must not impose on
the contractor any labor or material which is not called for by the spirit and
intent of the "General Drawings" and "Specifications."

(e) The Supervision of an architect (as distinguished from the con-
tinuous personal superintendence which may be secured by the employment of
a clerk-of-the-works or inspector of construction) means such inspection by
the architect or his deputy, of work in studios and shops or a building or other
work in process of erection, completion or alteration, as he finds necessary to
ascertain whether it is being executed in general conformity with his drawings
and specifications or directions. He has authority to reject any part of the
work which does not so conform and to order its removal and reconstruction.
He has authority to act in emergencies that may arise in the course of con-
struction, to order necessary changes, and to define the intent and meaning
of the drawings and specifications. On operations where a clerk-of-the-works
or inspector of construction is required, the architect shall employ such assist-
ance at the owner's expense.

11. Drawings and .specifications, as in.struments of service, are the
property of the architect.



New Method of Bonding Layers of Concrete

The problem of securing a perfect and durable bond between successive
layers of concrete, is solved, according to the Cement World. It is the
discovery of. Mr. J. A. Jamie.son, of Montreal. Quebec, and is said to have
been employed with highly satisfactory results in a variety of work,
including the construction of a reinforced concrete elevator and a reinforced
concrete conduit 10>4 feet in diameter and 8,000 feet long, wDvking under
33 feet head.

The surface of the concrete, approximately horizontal, is allowed to
stand until water which may have flushed to the top has disappeared.
When this result is attained, and while the mass is still moist, the entire
surface is covered with a one to one dry mixture of cement and sand, to a
thickness of about J/^ inch. If necessary, this is protected with tarpaulins
or boards. The moisture on the fresh concrete produces a partial set in
the dry mixture. This is true of the particles in direct contact with the
green concrete, the effect diminishing rapidly, and the upper portion of
the dry mixture remaining unaffected. The next layer of concrete is
applied without removing the dry layer, the moisture in the fresh concrete
completing the set through the half-inch dry layer, and producing a decided
bond of the two courses. Briquettes made of cement mortar in two parts
and joined by this method developed a strength more than half as great
as others made of the same material in a single piece.



92



'ilic .Ircliitcct and Engineer



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The Architect and Hngiiiccr 93

The Science of Mixing Mortar

TllERK arc just n-aMHis to niarxcl at llio carclcsMio. - with which an
average batch of iiinrlar is mixed ami i)histei"e(l riii the walls of a
structure. This is a matter that has been so long neglected that most
of our builders are inclined to consider it in the light of a subject that has
nothing to concern them beyond the mixing of the lime and sand. In this
age of supposed progressivcness, when cverj^ detail is, or at least should
be, given careful consideration the subject of mortar has been permitted
to remain comparatively unnoticed, and the work of mixing the same left
to almost any one.

It is true that we arc in a hurry, and that, in order to got our con-
tracts completed, we must adopt the methods that will insure the quickest
results. In this way there are liable to be some serious mistakes made,
and to avoid these we must have due regard for all of the details. Mortar
properly mixed and permitted to stand (this is the whole secret) will
naturally insure excellent results when tiic same is applied to the walls of
a building. How often is this done with care? Is it not the rule to mix
the mortar and use it too soon? We make the bed, slack the lime and in
a day or so add some sand; then the plasterer goes to work and if the
plastering falls off within a few months what else can we look for as a
result of this haphazard method of work?

■Any one who has the least knowledge of lime and its properties is
full}- aware of the fact that it requires a certain temperature to properly
disintegrate the same, and that the quality of the lime must be of the
best to get the desired results. Overburned or underburned lime will be
unfit for use where we hope for the best results, and this is, of course, the
])rimary consideration. But with good lime we must add care in the slack-
ing of the same and also permit it to undergo the chemical changes which
it requires before it will be in a state to give satisfaction.

Perhaps there are many who do not know that lime will undergo
some chemical changes for some months after it has apparently been
properly disintegrated or slacked. How we shall avoid the damage that
will naturally ensue from these changes is a consideration that should be
foremost in the mind of every builder. In ( lermany, for instance, the law
requires the lime to be slacked at least six months previous to being used
in mortar, and this is placed in wells especially dug for that purpose, where
it may undergo these chemical changes, so that it is in a perfect state when
it is mixed with the sand, and the plaster docs not fall from the walls
after being applied.

In this country it is the most common sight to sec a laborer, one who
has very little knowledge of lime, further than what he has learned from
every-day experience, mixing mortar on the street and the same being
placed on the walls a day or so later. What possible chance has the lime
had to undergo any real chemical change? Is the mortar made in this way
in a proper condition to be applied to the walls of a structure? The
slightest consideration will readily convince one that there is grave danger
of unsatisfactory results in such cases.

Why should we not have laws governing this matter? The contractor
and builder owes it to himself that more care be taken in this respect.
Our patent hard plasters, and wood fiber plasters where used, do away
with this possibility, but there are so many cases where the common
mortar is used that there should be some action taken by our municipal
authorities and building departments regulating the time limit shall be
used after it has been slacked. Is this not a theme that should be given
a deeper consideration? We are too prone to permit this matter to be
done in a way that will bring the least desirable results from our labors.



94 The Architect and Engineer

Consider that after the mortar has been placed upon a wall, when it
has been mixed in the ordinary way, that there are continual changes
undergoing in the ingredients, what are the results, and why does the
plaster fall, causing loss, inconvenience and labor? We would have more
regard for'every other portion of the building, and there is no excuse why
this portion of the structure should not be entitled to the same care as
any other. There is but one way to obtain this end, and that is bj^ co-oper-
ation on the part of every architect, contractor and builder to have laws
made governing the same. It is a matter that has been treated too lightly
in the past, and one that must be more carefully considered in the future,
because there is reason for the matter being remedied. What the builder
wants is the best of everything in his line and his workmanship to be above
reproach, and in this matter he can at least improve the condition of one
feature, and the results will amply repay him for the labor entailed.

Let us add that it is not necessary to use sand in the mixing of mortar,
because there are cases where ground limestone, crushed granite, or even
crushed cinders, have made a most perfect component part to be used in
conjunction with lime. The mortar made from any of the above commodi-
ties has been proven to give the most satisfactory results, and makes a
hard, durable plaster. The cost, where sand is scarce, is such as to make it
very reasonable, and it is a matter that is deserving of consideration, along
with the foregoing question of improved mortar. — National Builder.

Color Washes for Concrete

THE Department of Commerce and Labor has furnished Cement Age the
following formula for white and color washes for concrete:
Whitewash — Slake half a bushel of unslaked lime with boiling
water, keeping it covered during the process. Strain it and add a peck of
salt, dissolved in warm water ; three pounds of ground rice put in boiling
water and boiled to a thin paste ; half a pound of powdered Spanish whiting
and a pound of clear glue, dissolved in warm water ; mix these well together
and let the mixture stand for several days. Keep the wash thus prepared
in a kettle or portable furnace, and when used put it on as hot as possible
with painters' or whitewash brushes.

Cement Wash for Outside of Lighthouse Towers — Take of fresh
Rosendale cement three parts, clear sand one part, and mix them thor-
oughly with fresh water. This will give a gray or granite color, dark or
light, according to the color of the cement. If a brick color is desired, add
enough Venetian red to the mixture to produce. that color. The cement,
sand and coloring matter must be mixed together. If white is desired the
walls, when new, should receive two coats of cement wash and then white-
wash. After the work has received the first coat a single coat every three
or four years will be suiYicient. It is best to thoroughly dampen the wall
with clean, fresh water, and follow immediately after with the cement
wash. This course will prevent the bricks from absorbing the water from
the wash too quickly and will give time for the cement to set. Care must
be taken to keep all the ingredients of the cement wash well stirred during
the application of it. The mixture must be made as thick as it will admit
of to be conveniently put on with a whitewash brush.

The department adds that the whitewash made from this formula has
been found by experience to give nearly as good results on wood, brick and
stone as oil paint, and to be much cheaper. These washes have given
most satisfactorv results in the lighthouse service.



Tin- Architi'i-t and Eiii^inccr 95

Some Advantages of Hydrated Lime

I'.y R. K Mi-:.\i)r..

THE use of hydrated lime is a growing one with contractors and builders,
but many do not appreciate how useful an article it really is, and what
numerous advantages it possesses over lump lime.

Hydrated lime can be used for every purpose for which quick lime
is used, and also for all purposes for which lime putty is used. It has also
some uses which neither have. It, however, does not trowel quite so easily
as lime putty, and this has been the greatest objection on the part of the
mason to its use. By employing a- good deal of water in the mortar,
however, this objection can be to a great extent removed. The greater
convenience with which it can be handled and used, however, and the thor-
oughness with which it has been slaked, to a large extent make up for this
trouble. Xo mortar box is required and the hydrated lime and sand may
be mixed upon a board, just as are cement and sand. It is, therefore,
especially convenient for doing small jobs, such as repairs to plaster, etc.

It is estimated that it costs 25 cents per barrel to slake lime in a mortar
box. This expense is saved by the use of hydrated lime. Furthermore, the
mixing can be done indoors and in cities the streets are not blocked.

In using hydrated lime the mason should remember that not quite as
much water would be required as is the case with lump lime, because in
the case of quick lime some water is needed to combine with the lime, and
in case of hydrated lime this water has already been supplied by the manu-
facturer. Where a mortar box is used, it is usually considered best to first
place the water in the box and then the lime. More water and then lime
can be added as necessary, the idea being to get a thorough mix of water
and lime. It is usually considered better to allow the mixture to remain
over night. Such a mortar can be used just as lime ])utt3', and if plenty of
water has been employed, will trowel very similarly.

One place where hydrated lime can be used, where ordinary lime putty
can not be employed, is with Portland cement. The addition of lime to
Portland cement is not an adulteration, but confers a great many good
properties to the latter. It has long been known that slaked lime would
waterproof concrete. This is due to the fact that it exists in the form of
an extremely fine powder, many times finer than the finest ground cement.
This fine powder fills in the pores of the concrete and stops them up, thus
excluding the w'ater. Owing to the difficulty of mixing the wet lime putty
with the dry cement and sand, however, it has only lieen since the intro-
duction of dry hydrated lime that slaked lime could be used for water-
proofing. It is generally considered that hydrated lime is the best water-
proofing compound which can be added to cement, and that it is superior
in lasting qualities to any of the waterproofing compounds at the present
time advertised for this purpose. The writer has tested some eight or ten
of these compounds. In every instance, without exception, they decreased
slightly the strength of the cement mortar made therefrom, and he does
not think that any of the manufacturers claim that they add to the strength
of concrete. Hydrated lime, on the other hand, not only waterproofs the
concrete, but numerous tests made in difl'erent laboratories by disinterested
parties show that additions of hydrated lime up to 15 or 20 per cent increase
the strength of cement mortar.

As an actual waterproofer, hydrated lime is not surpassed by any of
the waxes and paraffin compounds at the present time used for this purpose.



96 TIic Architect and Engineer

Many of these compounds are organic, and in time will volatilize. leaving
the concrete porous. Hydrated lime, on the other hand, is inorganic or
mineral, and will remain where it is put.

As an example of the waterproofing properties of hydrated lime, this
was employed upon a large gas holder at Kingston, Ont., which had been
practically a failure, owing to the leakage of the concrete wall of the gas
holder. A number of waterproofing methods were tried, all of which failed,
and it was not until this wall was chipped back from three to six inches by
means of pneumatic chisels and a new wall composed of concrete, con-
taining about 18 per cent of the weight of the cement of hydrated lime had
been added, that the tank was waterproof.

The addition of hydrated lime to cement makes the latter more plastic
and easily trowelled. It also improves the adhesive properties. A mixture
of equal parts of hydrated lime and Portland cement makes an ideal mortar
for laying brick. The addition of hydrated lime to concrete blocks makes
the latter whiter, tougher, and waterproof.

For household, agricultural and industrial purposes, where only a small
quantity of lime is used, and where storage in the cellar or a shed upon the
premises is desirable, hydrated lime is unsurpassed, owing to the fact that
it can be easily mixed and handled, keeps indefinitely, is put up in small
paper packages (40 pounds), and finally that there is no danger of fire from
it. Lime has long been used as a disinfector, for whitewashing, for fertil-
izing, for spraying fruit trees, for purifying of water, for marking lawn
tennis courts, and for all of these uses hydrated lime possesses every prop-
erty of quick lime. For such uses as water purification, disinfecting, fruit
spraying, etc., magnesian hydrated lime has only about one-half the value
of the high calcium hydrate.

Hydrated lime is usually packed in 40-pound paper bags or 100-pound
cloth bags. The paper bags are of the valve type, and are pasted shut at
both ends, presenting a square package, which can be easily handled and,
owing to the absence of the rough tied end found in cement bags, can be
closely packed. Below are some standard formulas for the use of hydrated



Online LibraryHarpeth Hall School (1951 - )The Architect & engineer of California and the Pacific Coast (Volume v.25 (May-July 1911)) → online text (page 8 of 40)