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crete, finished flat on both sides, forming a solid block of one thickness, absolutely inde. structible.

19030. Homan and Rodgers' flat brick fireproof floors. They are constructed with hard burnt bricks, jointed in cement, and bonded on the upper face with tough concrete. The depth of the finished floor is 6 to 9 inches. "By the method of laying, the ironwork is protected from the action of fire. The brick soffit forms a key for the plaster; no laths or counterceiling are necessary, but, where desired, wood blocks can be fixed in the soffit to receive the ordinary lath and plastered ceiling, then making the most perfect sound-resisting fireproof floor known. The concrete being tough instead of friable, the boarded finish may be nailed down without the use of sleeper joists; but, since serious failures show that wood embedded in concrete, asphalte, or pitch, is liable to decay, it is recommended to use an inch strip as a sleeper fillet, which will also provide ventilation and space for gas and water pipes." The floor is stated to have no thrust.

1903p. Lindsay and Co.'s patent system, wherein a steel decking is introduced, and also their patent trussed concrete flooring. The steel flooring is manufactured of two different strengths, varying from 4 inches to 14 inches in depth, and suitable for spans of from 15 feet to 50 feet clear. It is stated as perfectly and equally distributing the floor loads to the surrounding walls, and as acting as a complete tie to the building; not affected by settlements of the walls; and is 30 per cent. lighter than ordinary arched floors. The trussed fireproof flooring is laid with pum ce concrete, enclosing small joists joined by steel truss rods twisted together every 18 inches; or formed as an arch underneath between girders to 14 feet span. A slab of this concrete, 2 feet span and 4 inches thick, was loaded to 22 cwt on the foot without injury. For a space of 30 feet the depth of the decking is only 5 in. to support a load of 1 cwt. per foot super. Brick partitions can be placed on this decking and concrete in any position, independent of walls or girders underneath. This flooring has been largely used in the National Liberal Club, by R. W. Edis, architect. The top table is made thicker than the sides, and the sectional strength is thereby greatly increased, and the various sections are riveted together at a point which is very close indeed to the neutral axis. The concrete is called "pumice concrete," as it is very light and tough; considered to be a good material for constructing roofs, domes, &c.

19039. The "Doulton-Peto" patent fireproof flooring, in principle consists of a series of hollow blocks of stoneware placed between rolled iron joists, making a flat ceiling, which may be plastered or not. The iron girders are fixed in the ordinary way, but not so close together as usual. The tile next to the side of the girder is specially shaped to set

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against and beneath it, so as to isolate it completely. The fig. 617, shows tiles made for a flat ceiling, and set in cement; if no ceiling, then the under side is made

smooth to receive whitewash, &c. The tiles for ordinary floors are 6 inches high and about 1 foot thick. The floor is stated to be one-third lighter than concrete or brickwork. A flat roof can also be formed with them. Where an arch is desired between each girder, another form of springer (fig. 617m). has been adopted. It has stood the test of upwards of 6 cwt. to the foot dead weight on material only, and with an arch of 6 feet span and quite flat. On an arch of 8 feet span a cask of graphite weighing 7 cwt. has been rolled and rocked, the vibration doing no injury. A fire has been lighted beneath, making it red hot in parts, and while in that state a hose has been turned on with a considerable pressure of water without the least effect. It has also been tested with unevenly distributed weights, and with vibration and concussion, all which it has successfully withstood. This flooring has been used throughout at the London Pavilion, where it was found very advantageous from its lightness, the speed with which it was constructed, and its cleanliness. A large building of four stories at Messrs. Doulton's factory has been similarly constructed by

Fig. 617m.

that firm; the under side of the flooring has not been plastered. (Builder, Dec. 19, 1885, p. 877. Transactions of the Royal Institute of British Architects, 1886, p. 130.)

1903r. Bunnett's patent floor consists of hollow bricks laid in the form of a flat arch, resting on angle irons tied together by tension rods. Each brick is so arranged as to receive support from six adjoining bricks. Measures' patent floor consists of iron joists with iron fillets 9 inches apart, at right angles to the joists, and resting on their lower flanges, and cement concrete filled in, embedding joists and fillets. Hyatt's patent dovetailed corrugated iron sheets are used for fire-resisting iron and concrete floors, ceilings, and partitions, giving great strength combined with lightness. Partitions can be made of Portland cement, concrete, and iron, only two inches thick, the iron being completely protected. The Wight fireproofing Company of America has introduced many novelties (Builder, 1887, p. 704). Porous terra-cotta is made in America by mixing sawdust with the clay; having been burnt it was perfectly fireproof, and although spongy, unless dipped in water it was not absorbent, but was rather a dry material, besides being one of the best nonconductors of heat and sound. It weighed about half that of ordinary brick. It was used to line outside walls to keep them perfectly dry; also as fixing blocks, because the nails could be driven into it more easily than into deals. It makes a good fireproof roof by placing sheets of it on the flanges of iron; it came a little above the edge, and the slates or tiles could be nailed directly on this. Fireproof flooring bricks were made of terra-cotta, and were a great saving in strength of materials.

19038. A concrete floor to the various stories of a building has often been formed, but not always with success. A system is explained in the Builder for April 3, 1886, which should be well studied. Concrete slabs, the largest of which is 21 feet by 12 feet 6 inches, of an average thickness of 13 inches, sustained the great loads and rudely impactive forces of a wholesale provision trade, in a warehouse at Sunderland, erected by Mr. Frank Caws, whose description, though concise, is too long to be here inserted.

1503t. If properly mixed, care taken in laying, and thorough cleansing of all broken materials used, then the results may be satisfactory. To receive stone paving and for tramways, concrete is laid in successive layers of cement and gravel in proper proportions, not too moist, for the requisite thickness, well beaten down with iron beaters. For a floor finish, a thick layer of about an inch of the cement and gravel finished off with a smoother, care being taken not to work up too fine a surface. The proportions to be used are 1 part of Portland cement, 4 of gravel, and 6 of broken stone, the latter to pass through a 24-inch ring. Concrete flat floors are cheaper and equally as strong as arched floors, and should be at least from 5 to 6 inches thick. Such a floor will carry a safe load of about 5 cwt. per superficial foot. One tested went further. It was made of 1 of cement, 3 of gravel, and 3 of well-washed broken stones to pass a 14-inch ring, the finishing layer being of cement and gravel. The Portland cement should be tested, for its proper strength is of importance. (John Garthwaite, of Liverpool, 1885.)

1903u. For town buildings these various patents afford the means for obtaining flat roofs, which have many advantages for the inhabitants, as affording a promenade. They have to be thoroughly well constructed. Two of the latest constructions are at the new City police station, Cloak Lane, Cannon Street, having a superficial area of 2600 feet, formed of iron joists, carrying concrete covered by a layer of one inch of the finest Pyrimont-Seyssel asphalte, the skirtings being of the same material; a thin layer of very fine and clean pebbles from the sea shore were applied to the surface while hot. The other roof is to the Army and Navy Auxiliary Supply Association in Francis Street, Westminster, having a superfices of about 12,000 square feet, and is of the same construction.

CONCRETE BUILDING.

1903v. The Metropolitan Board of Works have approved of such structures, and have made the following regulations to be observed in their formation:-

I. The concrete to be used to be composed of Portland cement and of clean Thames ballast, or gravel, or crushed smiths' clinkers, or brick burrs, or small broken stones, or any hard and durable substance; and each to be passed through a screen having a mesh not exceeding 2 inches in diameter. Sand to be in, or added to, such materials in the proportion of one to two. All such materials to be perfectly clean, and free from all greasy, loamy, or clayey matter.

II. These materials and cement to be mixed in the proportion of not more than 8 parts of material as aforesaid, by measure, to one part by measure of the best Portland

cement.

III. In making the concrete, a box 2 feet by 4 feet by 2 feet, or other like proportions, is to be used for the materials other than the cement, and another box, capable of holding one sack or half a cask containing 2 bushels, is to be used for the cement. The cement and the materials are to be turned over at least three times, and thoroughly mixed together with water.

IV. The walls of the buildings to be carried up all round in regular layers with concrete thus composed, and grouted with cement in the proportion of 1 of cement

to 2 of clean sharp sand after each layer, until the walls are completed in height. The grout to be made as mortar first, and then thinned with water to the necessary consistence.

V. The concrete to be well and thoroughly bound together, so as to secure the complete adhesion of the materials and work during its progress.

VI. The thickness of walls to be equal, at the least, to the thicknesses for brickwork prescribed in the Building Act.

VII. Suitable cores to be used for flues, and also for recesses. stoneware or fireclay pipes, not less than half an properly pargeted.

VIII. Door and window frames to be built into the walls.

Flues to be formed with inch in thickness, unless

IX. The portions of the party walls and chimney stacks above the roofs of buildings to be rendered externally with Portland cement.

X. The rules of the Metropolitan Building Act, 1855, as to the use of timber in walls, and other rules of that Act, so far as they may be applicable to concrete buildings, are to be observed.

1403w. This concession was made after many attempts to obtain it, by Philip Brannon, by Tall, Drake, and others. Mr. Wonnaco't read a paper in 1871, On the Use of Portland Cement Concrete as a Building Material, which enters fully into the merits and demerits of this construction. It was supplemented by another paper, Remarks on Concrete Building, by A. W. Blomfield, who summarises the whole thus: The chief advantages are, I. Cheapness; II. Strength and durability; III. Rapidity of construction; IV. Economy of space. The chief drawbacks are: I. Its liability to failure, from the use of improper materials, or from the want of knowledge and proper care, or from the wilful misuse of good materials; II. The limits which the material and method of construction impose on architectural design and decoration.

1903r. J. Tall advertises concrete construction for cottages; door and window frames. Drake and Co., concrete building apparatus ; dovetailed self-fixing building slabs; marble and granite facing bricks; fireproof floors, doors, staircases, wall tiles, &c.; window heads, copings, terminals, steps; marble concrete baths. W. H. Lascelles has, panelled slabs and concrete backings screwed to stud work; walls built of Potter's patent cement slabs; plain and moulded concrete forms of all varieties in building and ornamentation, as window sills, door jambs, gables; concrete ceilings; and chimneypieces. The Eureka Concrete Company has steps, sills, strings, balusters, fireproof floors, mantelpieces, thresholds; copings; a concrete door of four panels, hung in position and fitted with lock. Faija's concrete, hardened by his new patent process. J. Wright and Co. have made an "improved concrete lintel," having a curved upper surface and a T iron passing through it lengthways; with their fixing block inserted to receive the sash or door frame. See also par. 1864i.; and ARTIFICIAL STONE.

1903y. In 1887 Mr. W. Simpson read a paper before the Royal Institute of British Architects entitled Mud Architecture, relating many methods of construction of similar materials in various countries; further interesting references were made in the discussion and correspondence of that year.

1903aa. CONCRETE AND CEMENT BLOCKS. Blocks formed of Roman cement, puzzuolana, lime, and sand, were soon suggested for such a purpose. Those made without the cement were found to be longer in setting, but eventually became the strongest. To these combinations potsherds were added, as Pliny relates was in use in the time of the Romans; increased toughness resulted. The late Mr. Walker, engineer, possessed specimens of Dutch terras, which had been used in Woolwich dockyard in the reign of George III. These were of very great hardness; in fact, gunpowder had to be used in breaking up the dock where it had been employed. For concrete and mortar for the river wall of the Houses of Parliament he used two measures of sand, 1 of puzzuolana, and 1 of lime. Mr. Lee used Portland cement, Portland stone chippings, sand, and shingle, in blocks in cubes of 16 feet and upwards, made in moulds, for the breakwater at Dover. Mr. Blashfield had made experiments for that work with Lancashire terras mixed with broken tiles and sand; but it was not deemed equal in hardness to the Portland cement concrete blocks. 1903bb. Atkinson's or Mulgrave cement was used by its patentee for concrete blocks of shingle, sand, and cement, used as ashlar stone in the case of a house at the corner of Mount Street, Grosvenor Square, still standing in a substantial condition. Concrete in small blocks, known as Ranger's patent artificial stone, has been used to a limited extent in the construction of domestic buildings. It was employed in the additions to the College of Surgeons, Lincoln's Inn Fields, 1835-6; a guard-house in St. James's Park; the Imperial Assurance Office, in Pall Mall; and in a row of houses in the Western Road, at Brighton, partly in blocks and partly in moulds as pisé work. This process is not continued, probably from the mortar not being properly mixed in the first instance, and the concrete being exposed too soon to the action of the weather, for it dries unevenly, and cracks in all directions.

1903cc. Buckw U's Granitic Breccia stone was patented about 1858 to compete with brickwork in price, its strength and durability being greater, and its bulk and weight considerably less. It was impermeable to wet and never vegetated, so that for pavements and linings for tanks it appears to have answered well; but for some reason, not ascertained, the manufacture of it was lately given up. It could have been manufactured in a single piece, of a weight varying from 1 cwt. to 60 tons or more; also in slabs from 5 feet to 100 feet superficial; and to any contour. Wheeble's Reading Abby patent concrete stone, formed with Bridgewater stone lime, when made into a brick, was found to be equal in strength to a common stock. Some specimens never attained the strength of concrete except in a case where large gravel or flint was the chief ingredient. Messrs. Bodmer's patent compressed stone bricks, compounded chiefly of 1 part of hydraulic lime and 7 of siliceous sand, well mixed, are subjected to great pressure in moulds. Upon removal, the bricks are piled up in the open air, when induration commences, and the material is converted into stone. They appear to be ready for use after six weeks' to two months' exposure, and experiments show a steady progressive increase in strength as they advance in age. When eleven days old they crushed at 377 tons; at twenty-two weeks from 54 to 6.95 tons; and at sixty-three weeks a pressure of upwards of 8 tons was reached without effect.

1903dd. Coignet's Béton Aggloméré has been employed in France in the construction of a church in the park of Vésinet, near St. Germain, from the designs of M. Boileau, and into the construction of which he has also introduced cast and wrought iron. The béton is formed with all the mouldings of Gothic architecture both externally and internally. It was built similar to pisé work, though it is also applicable for blocks, like stone, in which manner he has lately executed some bridges of 140 feet span. The very hard frosts of January, 1865, had not appeared to have had any effect on the béton at the church, which was being executed at the time, and is described in the Builder for November, 1864; views are also given in the volume for 1865. It is stated that such structures cost only about one-half or perhaps one-third of the expense of a stone building, with greater decoration.

1903ee. The system of building with concrete blocks at Sandown, Ventnor, and other places in the Isle of Wight, is weli adapted for constructing walls to ensure dryness. The blocks are about 18 inches wide by 12 inches high, and are of two thicknesses, those for the outer wall being 4 or 5 inches, and for the inner about 3 or 3 inches thick. These are tied together by pieces of iron, leaving a space of about 3 inches between them. This forms what looks, to those accustomed to the 2 feet thick solid walls of Scotch houses, a flimsy wall, but it appears to be sufficiently strong for carrying another story over the ground floor; and with a few openings above and below for the admission of air into the space between the walls, forms a structure which, in a sanitary point of view, may be considered perfect. Some would prefer to have the inner wall of brickwork.

1903. TABLE OF THE RESISTANCE TO THRUSTING STRESS OF NINE 2-INCH CUBES OF CONCRETE, BEDDED BETWEEN PINE THREE-EIGHTHS OF AN INCH THICK. By D. Kirkaldy, for W. H. Lascelles, May, 1881.

[blocks in formation]

1903gg. The use of concrete has extended from the foundations of buildings, backings of wharfs, retaining walls, and abutments of arches, to the employment of it for the backing of vaults to produce a level surface; for the substance of fireproof floors; for the base of floors, pavements, and roads; for the walls, floors, &c. of houses, bridges, and moles; and various other purposes.

1904. Many ornamental brick cornices may be formed by but little cutting, and changing the position of the bricks employed, and several, indeed, without cutting, by chamfering only. Of late years the machines for making bricks have permitted the extensive use of moulded bricks of different forms, which have entirely superseded the more artistic advantages of cut brickwork to required outlines or ornamental details.

1905. Niches may be formed in brickwork. They constitute the most difficult part of the bricklayer's practice. The centre will be described under the section CARPENTRY. The difficulty in forming them arises from the thinness to which the bricks must be reduced at the inner circle, as they cannot extend beyond the thickness of one brick at the crown or top, it being the usual as well as much the neatest method to make all the courses standing.

1905a. Flues. It has been an established rule to build flues 14 inches by 9 inches, 14 inches square, or larger, for kitchen fireplaces, because it suited the size of the bricks and bonding, contained a sufficient amount of superficial area, and afforded a space for a boy sweeper to ascend them. Since then circular pipe flues, 8, 9, 10, 12 inches diameter, or oblong pipes with rounded corners, have been adopted by many, the inside being smooth. These are easily swept, and no lodgments of soot and brick rubbish take place. An objection has been made, if the pipes be glazed, that during a storm, or other concussion, the soot falls down into the room if the register flap be not shut. These pipes make good work at the gatherings. It is almost an invariable rule to make the flue the same size throughout; there is also the theory that the flue should be made larger at the top, and also smaller at the top, similar to a factory shaft. Also that a tall-boy is useless, for the top should only be finished by a terminal of a few inches, just sufficient to divide the rushing currents and allow them to pass between each pot. The fireplace should be covered over at the usual springing line by a slab of stone, or concrete, or iron plate, with an aperture in the centre of the size of the intended flue. On this the brickwork is carried up. Above it, in the breast, has been formed a chamber with sloping sides, to counteract any down draught.

19056. A brick flue is pargeted inside to render it smoke proof, that the velocity of the draught should be assisted or improved, and to prevent as far as possible the lodgment and accumulation of soot. The parget, which is a mortar made of a mixture of lime and cow-dung, should be sparingly applied, but sufficient to fill up open joints and all irregularities in the brickwork. If applied thick, it shrinks and cracks, and falls off, and assists in making a chimney smoke. It is now recommended to use the ordinary mortar for this purpose, the brickwork being kept as smooth inside as possible, by careful pointing, as it has been found more successful for a number of years.

1905c. PAVING. When neither slate, granite, Yorkshire or other stone, flint, nor shells, are used for paving, recourse is had to bricks, tiles, and asphalte. A yard superficial of brick paving requires 32 to 36 stocks laid flat; 48 to 52 laid on edge; 36 paving bricks laid flat, 82 on edge; 140 Dutch clinkers on edge; 9 twelve-inch tiles; and 13 ten-inch tiles. Brick paving is laid flat in sand; jointed in mortar; jointed in cement; and laid on edge, in the same manner. Tile paving is generally laid in sand or mortar (par. 2282h). Besides the ordinary brick, some others have been introduced, especially for stables and yards, such as the Terro-metallic grooved bricks, and Towers and Williamson's Adamantine clinker paving bricks for stables and yards; it is stated to be superior to the old Dutch clinker in shape, colour, density, and wear (par. 1829). Tebbutt's patent safety brick for stables and yards, &c., is considered to ensure perfect foothold, drainage, easy cleaning, saving in labour and straw, to form a durable floor, and to have a good appearance, Each brick is 5 inches by 10 inches by 24 inches; and the gutter brick is of the same size. Homan's Quartz, Granite and Ferrolithic stone paving, for streets, public buildings, breweries, warehouses, stables, schools, &c. Bennett's improved Granitic stone, for pavements, &c. (1887), is said to be fire, damp, and vermin proof; the surface, though hard and indestructible, is not slippery, it does not absorb moisture, it is laid from 1 to 3 inches in thickness, is unaffected by the weather, and hardens by time. Macleod's Metallic concrete is proof against fire, vermin, damp and frost, not slippery, and can be used for paving, wall linings, roofing, &c. It is very hard, and has been used in stabling, breweries, workshops, &c., from before 1870. Stuart's Granolithic and impenetrable pavement (1869), is very largely employed in this country and abroad. Wilkes' patent metallic paving and Eureka concrete is used at the war office, the firebrigade stations, and police stations. W. B. Wilkinson & Co. patent a specular granitic concrete pavement, which is formed in 15-inch squares of 1 inch thickness, ground perfectly flat, presenting a spotted appearance of red and different shades of grey colours. It may be laid on ordinary mortar, can be used for outside purposes, and is

stated to cost less than tiles.

1905d Ordinary tile paving is made of about 8, 9, 10, 11, or 12 inch tiles, of a hard and well burnt clay. The 11-inch tiles used in the footpaths, which are each 14 feet 6 inches wide, of new Westminster bridge, were made by Blashfield, and were laid diagon

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