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The Pamphlet Collection of Sir Robert Stout: Volume 73
Concrete
Concrete.
Unlike brickwork and masonary it is not necessary to employ skilled labour, any intelligent man can mix and lay concrete; at the same time the more skill and thought exercised in the manipulation, the more satisfactory will be the result.
We should be glad to see in architects specifications a clearer definition of the method to be used in the manipulation and laying—especially providing "that the water shall be supplied through a fine rose," not thrown upon the heap from a bucket as may be frequently seen.
The following hints may be found useful, and if followed should ensure satisfactory results:—
The "aggregate" must be clean and sharp, if it contain clay, earthy substances, ashes or grease, it should be thoroughly washed.
When sand is used it should be as coarse and rough as is obtainable; fine, silty or micaceous sand seriously weakens the mass. Large stones may be profitably employed in "packing" concrete, but should be placed far enough apart to admit of the interstices being completely filled up. The proportion of cement to "aggregate" will depend entirely upon the purpose of the work. To resist pressure of water the maximum quantity of cement should be used, and the work allowed to stand as long as possible before admitting the water.
page 16
Mr. William Smith, M. Inst., C. E. Aberdeen, found from [unclear: dis] experiments as to the permeability of concrete, that three [unclear: months] required to set the work thoroughly before submitting it to [unclear: press] clue to head of twenty-four feet.
- 1 part cement.
- 2 parts sharp clean sand.
- 8 parts screenings.
- 6 parts 2½inch metal.
It must be remembered the less cement used, the longer the [unclear: w] will take to harden.
A quick and accurate method of determining the voids in [unclear: broke] stones is to fill a box or other receptacle with the stones, [unclear: measure] cubical contents, then pour in the water until full—the measure [unclear: of] the water will represent the voids hence the proportion of mortar to stone.
In putting concrete into position it should never be thrown [unclear: fr] a height or sent down a shoot, the aggregate and matrix get [unclear: separate] and the value of the mass as an even and solid concrete destroyed.
After depositing, the concrete should be well rammed until [unclear: the] moisture comes to the surface. In using concrete under water, [unclear: can] must be taken that the water is still; a current whether [unclear: natural] caused by pumping will carry away the cement and leave only [unclear: cle] stone. Always provide a mixing board or platform which enables [unclear: th] workmen to freely work their shovels under the materials [unclear: to] operated upon, and prevents the addition of foreign matter. [unclear: Havi] measured the materials and the cement, turn the whole over ([unclear: with] spreading motion) twice dry, and in turning over the third time add the necessary quantity of water with a rose; turn this over once more [unclear: and] the concrete is ready to be deposited where required.
| (1) | That the aggregate be clean, sharp, free from clay or [unclear: dir] and thoroughly mixed with the cement before adding the water. |
| (2) | That such quantity only as will be used before setting commences be mixed at one time. Cement that has [unclear: partially] if mixed up again, never hardens properly. |
| (3) | When concrete or cement is used in conjunction with [unclear: sand] wood, or brick work, or such materials, the latter should [unclear: be] well saturated with water to prevent absorbing it from [unclear: the] cement. |
| (4) | Especially for plaster work, or in testing, cement should [unclear: be] properly cooled by being spread on a dry floor for at [unclear: least] hours before using. |
Note—Occasionally a suggestion is made that it would be advisable to pack our cement in casks instead of bags We beg to point out that the custom is in vogue in England where sacks are universally used, except for shipment abroad. We are always prepared to buy empties returned in good condition. Moreover, bags are much more economical than casks, as they are more easily handled and emptied, the saving of time on a large job being very considerable
| 7 days | 28 days | |
|---|---|---|
| February, 1894 | 426 | 546 |
| March, 1894 | 496 | 684 |
| April, 1894 | 480 | 566 |
| May, 1894 | 528 | 645 |
| June, 1894 | 474 | 670 |
| July, 1894 | 436 | 536 |
| Average | 473 | 608 |
Briquettes: 1" Section, and were broken by Adie's machine. The Government specification is 300 lbs. per square inch at 7 days, and 450 lbs. at 28 days.
Specific gravity: Mean, 12 tests, 3.125.
Average residue: 2.500 per square inch, less than 6 per cent.
page 18
One Hundred References where "Maori" Portlan Cement has been used.
- Allandale Coal Company
- Art Gallery N.Z. & S.S. Exhibition
- Anderson & Co.'s mill, stores & stables Apron, &c., Water of Leith
- Dr. Burn's Monument, Dunedin
- Benevolent Institution (Old Men's Home)
- Catlin's River Tunnel, Otago
- Canterbury Railway Department,
- Culverts, Buttresses, &c.
- Castle Hill Coal Company
- Convent Buildings, Dunedin
- Christchurch City Corporation
- Dairy Floors N.Z. & S.S. Exhibition
- Dairy Factory, Moray Place
- D.I.C., Floors & Buildings, Dunedin
- D.I.C., Premises, Christchurch
- Dunedin Salvation Army Barracks
- Dunedin City Corporation Works
- for past five years
- Dunedin Hospital Pavilion
- Dunedin Roman Catholic Cathedral
- Exhibition Buildings
- Engineering and Electrical Co.
- Residence, E. B. Cargill, Esq.
- Flour Mill, Mosgiel
- Freezing Works, Burnside
- Flour Mill, South Dunedin
- Gas Works, Retort House, P. Chal'rs
- Gas Works, Dunedin
- Gas Works, Caversham
- Granity Creek Westport Coal Co.
- Horse Sale Yards, Wright, Stephen-son & Co.
- Kaitangata Coal Co.
- Linwood Town Council, Canterbury
- Lambert's Pottery Works
- Leith Street Bridge
- Mornington Borough Council
- Mornington Public School
- Mataura Paper Mills, Dam, &c.
- Manse, Burnside
- Manse. High Street
- Maori Hill Borough Council
- McLeod Bros., Ltd., Additions to
- Soap Works
- N.Z. Drug Co.'s Works, Burnside
- Nurses Home, Dunedin Hospital
- N.Z. Midland Railway Co.
- Oamaru Breakwater
- Office & Warehouse, Mr. Henry Rose
- Otago Central Railway
- Otago Heads Battery
- Provincial Hotel Buildings
- Public Works Dept., Wellington
- Public Works Dept., Christchurch
- Public Works Dept., Dunedin
- Public Works Dept., Invercargill
- Phœnix Jam Factory
- Paper Mills, Woodhaugh
- Port Chalmers Sewerage Works
- Police Station, Dunedin
- Post Office Tower, Invercargill
- Police Station, Naseby
- Porirua Asylum, Wellington
- Queen's Theatre, Alterations
- Rangiora Borough Council, Canterbury
- Residence, St. Clair
- Rope Works, M. Donaghy & Co.
- Roslyn Borough Council [unclear: Car]
- Reservoir, Ross Creek
- Roxburgh G.M. Co.'s Reservoir
- Roman Catholic Church, S. [unclear: Dunedin]
- Roman Catholic Church, N.E. [unclear: Valley]
- Roman Catholic Church, Oamaru
- Roman Catholic Church, Hyde
- Residence, Littlebourne (J. [unclear: Robe] Esq.)
- Shacklock's Foundry Chimney [unclear: St]
- Seacliff Asylum Waterworks, &c.
- Sunnyside Asylum, New Laundry
- Sheer Legs (80 tons) [unclear: Foundatio]
- Port Chalmers
- Sydenham Borough Council [unclear: Public]
- Swimming Baths
- Sydenham Borough Council
- Supreme Court Additions, Christchurch
- St. Albans Borough Council
- Speight & Co.'s Brewery
- Taieri County Council, Bridges, [unclear: Cverts], &c.
- Theological College, Dunedin
- Universal Bond, six Strong Rooms
- Victoria Hot Salt Water Swimming Baths
- Workshop, A. & T. Burt
- Wool stores, Wright, [unclear: Stephens] & Co.
- Wool Stores, Mutual Agency Co.
- Wool Stores, Stronach Bros. & Co.
- Wesleyan Church, South Dunedin
- J. Wilkie & Co.'s Printing Works
- Walton Park Coal Co.
- Ways and Works Department, N.R Railways
- Wellington City [unclear: Corporation,] pavement flags
- Warehouse, Mr. Sew Hoy
- Waimate County Council
- House of Representatives, Wellington
- N.Z Government Life Insurance Building, Wellington