Foundations and foundation walls

Front matter

Shelf

UNITED STATES OF AMERICA.

FOUNDATIONS

Chapter I

Foundation walls on soil or stratum not liable to be affected by weather, air or water.—Clay.

CHAPTER H.

Foundations in soft ground of considerable depth.—Boring to test bottom. — Timber pile foundations. — Foundations in quick¬ sand. — Foundations in shifting sand. — Structures built on slopes.—Pile driving.—Terms used in pile driving.—Size and kind of wood for piles.—To find safe load for pile to carry.— Height of ram to fall.—Set of pile at last blow.—Weight of rams.—Experiments in Brooklyn Navy Yard.—Protection of piles.—Decay and preservation of timber.—Worms in wood on land and in open air.—Worms in wood under sea-water.

CHAPTER HI.

Excavations.—Rule to be complied with.—Footings and footing courses.—Chimneys.—Trenches for footings.—Springs in cellars.

CHAPTER IV.

Stone foundations.—Walls.—Brick for footings.—Use of stone for building purposes.—Strength of building stone.—Footing stones. —Inverted arches.—Table of weight of timbers.—Weight of building stones...

CHAPTER V.

Arches in walls.—Construction of arches.—Chimney walls and build¬ ing the same.—Proportion of brick chimneys.—Masons’ and stone-cutters’ tools. — Stone-cutting.— Rubble footings—Bond rubble. — Random coursed stone work.—Regular faced and squared stone work.—Trimmed and coursed Ashlar facing.— List of stones for the exterior of buildings.—Dry area of brick

9—12

13—32

33—41

42—58

VI

CONTENTS.

or rubble.—Prevention of dampness in cellar walls.—Sylvester’s process of repelling moisture from external walls.—Damp.— Hollow brick walls.—Floors in damp locations.—Air and water¬ tight cements for casks and cisterns.—Cement for external use.— Cement to resist red heat and boiling water.—Cement to join sections of cast-iron wheels.—Soft cement for steam boilers.— Gas-fitters’ cement.—Plumbers’ cement.—Coppersmiths’ cem¬ ent.—Composition to fill holes in castings.—Cast-iron cement.— Cement for Aquaria...

CHAPTER VI.

Front vaults.—Retaining walls.—Slopes.—Table of strength of stone for vaults, galleries, etc.—Table of experiments on brick.— Table for calculating weight of materials in building.—Law in reference to load on floors.—Mensuration of superfices.—Hollow walls for buildings.—Building Laws passed Apr., 1871.—Preser¬ vation of stone.—Incrustations on brick walls.—Sulphuret of lime.—Sand. 77

CHAPTER VII.

Preparation of common mortar.—Gravel sidewalks.—To color bricks black.—Staining bricks red or black.—Venetian cement. Coalash mortar.—Puzzolana mortar.—Dutch Terras mortar.—Plas¬ tering or stucco.—Inside plastering.—Two-coat work and fin¬ ish. Stone mortar.—Stucco. — Scratch coat.—Slipped coat.— Cement for external use.—Asphalt composition.—Asphalt mas¬ tic.—Asphalt for walks.—Cement for fronts of houses.—Cement for tile roof3.—Cement for outside brick walls.—Mexican meth¬ od for making hard lime floors.—Selenitic mortar or cement.— Selenitic clay.—Mixing selenitic mortar and concrete.—Propor¬ tion of sand to lime.—Concrete construction.—Ancient cem¬ ents.—Rapidity of set.—Color.—Packing the cement.—Water for mixing.—Sand-gravel etc., for mixing with Portland cement. —Proportion of cement in mortar and concrete.—Mixing and laying Portland cement concrete.— Fineness. — Expanding or contracting in setting.—Strength.—Tests of cement.—Hydraulic limes and cements.—Salt-water mortars.—Mortars exposed to air.—Betons and concrete. — Portland cement.—French beton agglomere.—Vicat cement.—Lafarge cement.—Table of Amer¬ ican and Foreign cements.—Keene's cement.—Polished work of walls.—Stucco on brick-work.—Rosendale cement concrete. —Portland cement concrete.—Selenitic lime or cement.—Cem¬ ent mortar for brick laying.—Mortar of cement.—Cement mor¬ tar for stone masonry.—Cement mortar for brick masonry.— Ordinary concrete.—Brick-dust and cement concrete.—Lime and cement concrete.—Table of tests of hydraulic and other cements

CONTENTS.

VII at Centennial Exhibition.—Collingwood on cements.—Roman cement.—Vicat’s hydraulic cement.—Stone cement. — Glue.— Cement mortar.—Concrete.—Test of Portland cement.—Street pavements. — Macadamized roadways. — Artificial stone pave¬ ments for sidewalks.—Belgian pavement.—Guidet pavement.— Sidewalks.—Method of calculating load on floors.

ART OF PREPARING FOUNDATIONS

BY

FREDERICK BAUMAN, (ARCHITECT.)

FIRST PART.

Art of treating the ground.—Solid grounds.—Compressible grounds. —Building-ground of Chicago.— Method of isolated piers.— Concrete.—Semi-fluid grounds.

SECOND PART.

The Base.—Dimension stone.—Rubble stone.—Concrete.—Mortar. Base of chimneys.

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163-166

Foundations and Foundation Walls.

CHAPTER I.

Foundations.

The term Foundation is used to signify the bed or bottom of earth, gravel or rock which must be prepared to receive the base consisting of footings and foundation walls. The object to be attained in the construction of all foundation walls is to form solid footings of proper proportion to the superstructure.

Foundations may be divided into two great classes.

hirst.—Foundations in situations where the natural soil is sufficiently firm to bear the weight of the intended structure.

Second.—Foundations in situations where artificial supports must be provided in consequence of the softness or looseness of the soil. E^ach of these classes ma.y be subdivided into many kinds under the heading of Engineering works but it is the in¬ tention to confine this book more particularly to the founda¬ tions of buildings.

Foundation Walls on Soil or Stratum not liable to be affected by Weather, Air or Water. —In building on a natural bottom of this kind, it is necessary to level the surface or footing space, so that the walls or piers may start from a horizontal bed. If irregularities occur in the firm ground, it will be best to fill them up with concrete, rather than to use stone or brickwork. Where some portions of the foundations start below the level of the others, care must be taken to keep the mortar or cement joints as close as possible, or to execute the lower portion of the work in cement or hard-setting lime mortar.

Strong gravel may be considered as one of the best soils to build upon, as it is not affected by exposure to the atmosphere, and is almost incompressible and easily leveled.

While sand resists compression and makes a firm foundation, it must be kept from shifting, or being acted upon by water.

In many cases it is necessary to drive sheath or board piles and use cement.

Rock or partly solid rock bottom requires good judgment and careful handling; for it commonly happens, in the area of a large building, that some portions will rest on rock and others upon clay or loose gravel, and these differences in the character of the soil, are liable to produce irregularities in settlement, and are often difficult to make firm enough to carry the load of masonry uniformly. A common rule, when possible, is to reduce the rock to a certain level, sufficiently deep for the footings, and then remove the soft soil, and make a bed of say three feet of concrete, bringing the concrete to the level of the stone; all of which is explained by the following practical illustrations.

To prepare the surface of stone bottoms of irregular or in¬ clined strata, it is necessary to reduce the stone or brick to level surfaces, thus—(ill. I and 2.)

Illustrations i and 2.

or quarry, excavate, and carry the whole to a common level.

Beds of Rock with clay are not very safe without artificial treatment, especially if there are partings or strata of clay, and if they lay in inclined positions. In ill. 3, for instance, when

AND FOUNDATION WALLS.

II turning arches, the springing line or base of arch on one side might be secure, while the opposite side would be liable to move from the pressure of the load on the arch; this may be made secure by drilling, and driving iron bars into holes pass¬ ing through the strata.

Clay. —The most deceptive kind of ground to build upon is clay. Its insecurity results from the position of its strata, as well as its elasticity, from being mixed with marl, etc., and its tendency to absorb moisture. In dry seasons it is very firm, while in wet seasons it is elastic and unreliable. It is known that whole buildings have been injured by the moving of clay strata. Of course this insecurity is not likely to occur on level strata or firm clay.

But when the layers of clay are inclined, too much care can¬ not be observed, especially where the distribution of the load is quite uneven, as for instance in structures where piers, towers, or chimneys occur along with solid walls. It is always well to disconnect towers.

When dry clay rammed around foundation walls becomes wet, it has a tendency to bulge them.

All buildings settle a little, if from no other cause than the weight of the walls and floors.

Shifting clay bottoms that are very insecure have been built upon by laying round timbers, one foot apart, on concrete ; the space between the timbers being laid with concrete, and filled to the top of the logs, to receive stone-slab footings. This method will do on structures of about thirty feet in height, and inexpensive buildings.

The best soils for foundation walls are: gravel and close pressed, hard, sandy earth that will resist the pick—or rock bot¬ tom where a horizontal base may be made.

If there is reason to believe that the earth below is yielding it is best in ordinary cases to dig rough wells and fill them with stone to the footings in the cellar bottom ; dig say 6 feet be¬ low cellar bottom. These wells may be arranged to support walls of 40 to 145 feet in height.

AND FOUNDATION WALLS.

Chapter II

To Secure Solid Foundations in Soft Ground of considerable depth.

In cases of this kind where the expense of building from a great depth to the surface is too great, a number of supports or columns can be brought up through the soft ground, on which to set wall plates of wood, stone or iron for footing courses. There are a variety of ways in which this may be done.

First: By excavating holes through the soft ground, and fill¬ ing with sand; this is done by boring, or driving down a wooden pile, then withdrawing it and filling the hole with sand. This method is not often used in this country, although if an ample number of holes are filled with sand well packed, a secure foundation may be obtained.

Second.—By driving piles of wood either by hand or with the ordinary steam engine ; the piles to be driven until they are firm and secure in the solid earth, and kept from any side movement by bracing with horizontal timber.

Third.—By screwing piles into the soft ground for a bearing. The screw fixtures attached to piles are expensive and are not generally used on city buildings.

The cast or wrought cylinder screw piles are usually from 3 to 8 in. diameter and have at the foot a cast screw with a blade from 18 in. to 5 ft. diameter; they are generally used on docks and railroad work and are screwed into clay, marl or sand by using capstan bars. On engineering works where many of these piles are sunk a special machine is used for the purpose, generally worked by steam. This system of piling is too ex¬ pensive for buildings and is seldom used except on dock work.

Certain kinds of soft soil have a tendency to stir into a mud batter upon driving piles into them. In this case drive with hand power a few guide piles and then build square or parallel cribs of timber and fill the space with stone closely packed, also rip-rap stone on the outside securely packed; in some cases it may be necessary to make a timber bottom secured to the crib. When these foundations are made, test them in several places with bars of pig iron ; cover an area of io sq. ft. with a load four times greater than the total load to be borne, including ma¬ terial etc., to each sq. foot of horizontal surface. All calcu¬ lations for purposes of this kind vary, but the above test will be found satisfactory.

Fourth.—Excavate or make a cutting into the soft bottom and sheath pile with boards braced on both sides and as the ex¬ cavation proceeds, sink the sheath piles in courses. When sufficient depth has been obtained, fill in with a concrete composed of broken stone, cement and sand.

Fifth.—By sinking hollow cylinders of cast iron or cast iron pipe until they rest upon the bearing strata, removing the soft material from the interior of the cylinder to enable it to descend. If used to resist sea water the iron should be close-grained, hard white metal. This quality of iron is known to have resisted the action of saline salts for at least forty years.

But poor quality of iron is eaten by the salt and soon becomes soft. Large cast iron cylinders from two to five feet diameter are used for pipes. They are usually cast in lengths, say from eight feet to sixteen feet. Short lengths are sometimes connect¬ ed by internal flanges or lap-joints—the first pile is sometimes provided with a seat, having cutters or a screw fixed with a com¬ pression ring after the pile is set.

On buildings this system of piles may be used with advantage for towers, piers, chimneys and heavy structures, but only in cases where simpler methods will not answer.

Boring to test the Bottom. —Boring in common soils or clay to test bottom may be made by a common wood augur of two in. diameter, This will bring up samples of the soil. The iron of the jointed rod should be of the best quality. When the test¬ ing has to be made to a considerable depth, it may be necessary to drive down a tube of wrought or cast iron, to prevent the soil from falling into the open hole. These tubes may be in short lengths, for convenience of driving, connected with screwjoints, and the earth may be removed from within by a long

AND FOUNDATION WALLS.

handled scoop. The important object to be attained in using an augur is to learn the character of the underlying strata. An accurate knowledge of which can be obtained only by repeated boring.

Timber Pile Foundations. —Timber piles when partly out of water are objectionable for permanent structures on account of their liabliity to decay. For that reason when they are used for foundations they are cut below the water line. The use of timber piles is very general in New York City and numerous examples may occur to the mind of the reader. We believe this an important subject and will explain the use and manner of driving these piles. First.—We may consolidate the soft or yielding ground by driving piles into k until it becomes so com¬ pressed that the piles are prevented from sinking by lateral fric¬ tion. The usual method is, after the earth has been removed to the depth required, to drive piles from 16 in. to 3 ft. apart as the necessities of the case may require, cutting them off to the level of the water line. A depth of say two feet of concrete is then filled in up to the level of the top of the piles; the hole is then planked over to receive the masonry of the superstructure. Sometimes the planking is laid, not on the piles but on a net

./BRICK wall i6 swell’s foundations work of horizontal timber. In timber piling the load is trans¬ mitted only in the direction of its length. There are also many cases where stone footings are used and laid directly on the top of the piles; but too much care cannot be taken in a case like this to obtain security.

Illustration 4 shows an elevation of framing on top of piles. This is the plan adopted in the construction of a factory built on the marshes near Hoboken, New Jersey. The building is 50 by 100 feet, and about 20 feet in height. The piles, of yel¬ low pine, were thirty feet in length, and from nine to twelve inches diameter. After being driven, they were cut to a level of two feet below water-line, and spaced for the outside walls four feet to centers. On top of these were placed sills. 12 x 12 inches; on top of the sills were-framed uprights, 12x12, four feet long, braced from all sides ; on top of uprights was placed a second sill, that received a twelve-inch wall. The piles for wooden pillars through center are eight feet to centers. The piles for the chimney and engine-room are about twenty inches apart, with timbers crossing each other, forming a foundation for stone slabs, on top of which is built the brickwork. The foun¬ dation of timber is cross-braced from center to outside; and notwithstanding the motion of the machinery, no unequal set¬ tling has occurred, although it may have settled one inch be¬ fore becoming fixed and solid.

Foundations in Quicksand.—

It is not uncommon to find quicksand in New York City. In many localities large masses of sand surcharged with water until it becomes quick are found at a depth of from 5 to 20 ft. In nearly all cases there is a mixture of leaden colored silt or soapstone slime. This is a kind of marl nearly white when it is dry, but when mixed with the sand holds a large amount of water. It is often the case in excavating through quick-sand that strata of this blue marl occurs ; it is tough and hard to move but it is utterly unfit for Foundations of any kind. An¬ other difficulty often occurs when layers of cemented clay and gravel are found. It is slow to dig with shovels or picks, and can only be taken out in small quantities, adding greatly to the expense. In nearly all cases where quicksand is found it will be necessary to provide hand or steam pumps with leaders or

AND FOUNDATION WALLS.

1 7

gutters, to remove the water. It is useless to attempt the re¬ moval of the sand and ooze until the water is drawn off and where any natural drainage can be obtained, channels should be made in every direction possible. It is often necessary in this kind of soil to provide temporary platforms and roadways, while making the excavation, as the disturbance of the soil con¬ sequent upon prosecution of the work is liable to make a slough. Where there are large masses of quicksand which are imprac¬ ticable to remove, owing to locality or surroundings, drive piles, not disturbing the soil more than is necessary, and secure them to horizontal timbers, forming cribs, then brace the whole and fill the interstices with concrete made of broken stone, sand and lime.

One way to proceed to secure footing in this soil is to drive sheath piles on the outside and inside line, leaving the space between to be excavated. Brace the sheath piles adding sec¬ tion after section, as the excavation proceeds. Have prepared concrete enough to fill in each section, proceeding in this way until the work is completed.

Where the soil offers no resistance to sheath pile or brace, construct long wooden cases with sides and bottoms (Caissons) made of 2 or 3 in. boards securely bolted and framed together. Set these in sections and in the position where they are to be lowered ; they are then to be loaded to the top with rough con¬ crete and sunk with their own weight to the depth required. Tests may be made by loading these cases with iron to the average weight, per sq. ft., expected to be borne. The combi¬ nation of quick sand, marl, hard-pan, etc., found in excavations is often carelessly passed by and ordinary broad footing stones used, resulting in many cases in unequal settling and the ruin of fine buildings. Broad footings of stone are allowable where the soil is not too soft, but two or three courses should be laid with a batter of half their thickness.

To build Foundations on shifting sand.

In speaking of this subject it will be well to state, that the place, condition of sand and the opportunity to secure the bot¬ tom of the structure will vary so much that these directions will hardly apply to every case. Excavate an open space in the i8 sand larger than the base of the structure, lay timber footings, parallel with the line of the walls, cross them with timbers un¬ til a solid platform is prepared and pin them together with oak or metal pins. Then make a diagonal cover of say i 3-4 in. rough boarding, either nailed or pinned ; on this platform or deck run sill plates to the size of the frame required and se¬ cure them to the timber footings, and on these sill-plates set the corner posts and put in braces ; then erect the frame construc¬ tion as may be necessary for the purpose. This platform or deck will require inclosing sides, thus making a large box to re¬ ceive the sand. The load of sand will balance and hold in po¬ sition the whole structure. It is estimated that each cubic ft. of space in a frame structure will average 15 lbs. and each cubic ft. of sand 105 lbs. or seven times heavier than the frame ; now if the frame is 35 feet high the box must be loaded with sand 5 feet deep. As an additional security long horizontal timbers with timber anchors may be extended from the bottom of the box. It is important to load the bottom of the structure and place it below the wash of the water. The weight of the sand alone need not equal the weight of the structure provided it is heavy enough to secure the foundations from shifting.

AND FOUNDATION WALLS.

Illustration 5 represents the foundations of a factory building erected near the edge of the water line in the marshes of Long Island. The soil is a stiff black muck. Trenches were cut through this four feet wide, and averaged six feet deep to a par¬ tial quicksand bed. The building is 50 by 80 feet; two stories, 16 feet each; with four feet of brickwork, above ground, to level of first floor. The walls above are sixteen inches thick. After the trenches were dug, a bedding of ten inches in thick¬ ness of concrete was laid. On top of this two inches spruce plank are laid crosswise, followed with 8x8-inch timber, laid parallel with the trenches, and the spaces filled in with con¬ crete. On this are laid the base stones, on top of which is built a twenty-inch brick-wall. The trenches on each side of wall were filled up with sand.

This factory has an engine, boiler, machinery and shafting, with an hundred operatives. No settling has occurred.

Structures built on slopes are always liable to slide. In prac¬ tice this is avoided by cutting horizontal steps in the slope, but great care should be used in erecting the walls to thoroughly bond the stone at all stepping places. Such work should pro¬ ceed slowly so as to avoid unequal settling as the greater quan¬ tity of mortar in the wall on the lower portions of the slope will cause much greater settling there than in the walls on the upper part of the slope and a consequent breaking of joints at the stepping places. The foundations should be leveled in as long sections as possible and the footings carefully laid, especial¬ ly at the stepping places.

Pile Driving —The usual method of driving piles is by a suc¬ cession of blows given by a heavy block of wood or iron, called a ram, monkey or hammer, which is raised by a rope or chain, passed over a pulley fixed at the top of an upright frame, and al¬ lowed to fall freely on the head of the pile to be driven. The construction of a pile-driving machine is very simple. The guide frame is about the same in all of them : the important parts are the two upright timbers, which guide the ram in its descent. The base of the framing is generally planked over and loaded with stone, iron, or ballast of some kind, to balance the weight of the ram. The ram is usually of cast-iron, with projecting tongue to fit in the grooves of frame. Contractors have all sizes of frames, and of different construction, to use with hand or steam power, from ten feet to sixty feet in height. The height most in use is one of twenty feet, with about twelve hundred pound ram. In some places the old hand-power method has to be used to avoid the danger of producing settling in adjoining buildings from jarring.

Piles should be driven to sink not more than one inch to the last blow of the hammer. The hammer used should be equal in weight to the pile. The common size of piles is ten to four¬ teen inches in diameter, and they are driven with hammers or rams weighing twelve hundred to two thousand pounds each. The diameter of the pile should be about one-twentieth of the length.

The present way of driving piles with steam power is very ob¬ jectionable where permanent structures are to be built, as the severe and frequent jarring is liable to work the soil into a soft mass.

Illustration 6. —Piles, &c., showing Water Line.

Terms used in Pile Driving. —A Pneumatic Pile is a metal cylinder and is driven by atmospheric pressure, the air being exhausted from within.

A Hollow Pile is a cylinder which is sunk by excavation pro¬ ceeding inside.

A Screw Pile has an augur at the lower end, and is sunk by rotation, aided by pressure.

A Close Pile is one of whole timber, set close to the others.

A False Pile is an additional length added to a pile after driving.

AND FOUNDATION WALLS.

A Filling Pile is to fill the space between gauge piles.

A Foundation Pile is one for supporting a structure.

A Gauge Pile is a preliminary pile to mark the desired course.

A Guide Pile limits the field of operation.

A Sheet Pile is of half timbers in contact, filling the gaps be¬ tween gauge piles.

A Wale is a horizontal string-piece to bind the piles.

Pile Hoop , a band around the top to prevent splitting.

Pile Shoe, the metallic point.

Test Pile, the first pile driven to test the bottom and should be not less than six inches in diameter.

i

Size and Kind of Wood for Piles. —Piles are generally round, and from nine to eighteen inches at top, and should be straight and clear of bark and projecting limbs, etc. But where piles are exposed to the rising and falling of tides, for wharves, tres¬ tle-work, etc., they are considered to be the best if driven with the bark on. Trees are sometimes selected for this purpose ; and when the foliage is full, just on the change, the tree is gir¬ dled—that is, the bark near the bottom is separated by cutting it off sufficient to kill the tree, and two or three months later the trees are felled. This method shrinks the bark close to the wood.

White pine, spruce, or even hemlock answer very well in soft soils. Florida yellow pine makes the best for general use but oak, elm and beech for the more compact soils. Piles are generally spaced from two to four feet to centres. Squared piles and ta¬ pering ones will not bear equal loads. All should be as near uniform in size as possible.

All timber, driven into the earth, having the common name of piles, may be divided by calling those that stand on solid foun¬ dations Posts, and those that depend on the friction of the earth and its constituents Piles, these last require to be considered very carefully for their sustaining power. Although piles may resist the hammer it is sometimes difficult to tell whether the resistance is from having reached a firm strata or as only caused by friction. In such cases always allow a large proportion for safety, and bind the piles together, or brace them. In nearly all calculations that are made for pile driving, the calculations are based on the soil being homogeneous , that is, assuming the soil to be the same kind all the way down. Now this seldom occurs, as there may be alluvium, clay, gravel, marl, shale or pebbles, and some variety occurs in nearly all localities. As it is difficult to find a locality to suit the formula, it is best to ac¬ cept the judgment of experienced builders, who are experts in this specialty.

The force in pounds with which a pile hammer makes its blows upon the head of a pile is very indefinite, as all the rules differ very much. Correct data may be gathered from actual tests, as follows : In the fine stone London Bridge crossing the Thames each pile sustains eighty tons. They are driven only twenty feet in the stiff blue London clay, and are four feet to centres, and are twelve inches diameter in the middle. This proved too much of a load. At about three feet on centres they would have had only forty-five tons to sustain. Trautwine states that at the Chestnut Street bridge, Philadelphia, the greatest weight on any pile is eighteen tons. Mr. Kneas had the piles driven until they sank three-quarters (.75) of an inch, .under each blow, from a 1200-pound hammer, falling twenty feet. Here we have the fall in inches : 20 x 12 = 240 inches, divided by .75 = 320 x 1200 lbs. = 384.000 lbs., divided by 8, = 48.000 lbs., or 21 1-4 tons safe load; but it is best in practice to use only one-half of the estimated safe load.

The refusal of a pile intended to support a weight of thirteen and a half tons, can be safely taken at ten blows of aram of 1350 pounds, falling twelve feet, and depressing the pile eight-tenths of an inch at each stroke.

Some engineers consider a pile safe for a load of twenty-five tons when it is driven to the refusal of 1350 pounds, falling four feet, not to sink more than four-tenths of one foot under thirty blows. On mud and marsh bottoms it is best not to load the piles more than one-quarter of the above amount.

The following are a number of rules for calculations in refer¬ ence to the strength and bearing capacity of piles.