Typical Example of Specifications

"Bridge, Staging, Scaffolding, etc.—Side walk bridges are to be built of proper materials, for the three fronts; steps are to be provided at each end of the bridges and wherever required, and necessary railings are to be put up. Shed roofs are to be built, extending the full width of the sidewalk and the full front of the building, covered with roofing felt, constructed of proper materials, to have cant-boards, posts, braces, etc.

"The Contractor is to provide, put up, and maintain all necessary electric lights, wiring, connections, etc., to supply electric lighting for the space under the shed roof, as required by law.

"Cemen.

All cements are to be of the very best quality, approved by the Architect; all are to be properly stored, housed, and protected.

"The following kinds of cement are to be used: La Farge Cement, . . . Portland Ce ment, and Rosendale Cement." Since the cements are to be tested and must be up to a certain standard, to specify the brand in addition, when there is a large cement market, seems unnecessary. A com mon clause is: "of . . . brand, or quality equal thereto." "The cements, when tested, must give a mini mum tensile strength per square inch as follows: Portland Cement 24 hours after mixing, 120 lbs.; 6 days, 300 lbs. Rosendale Cement 24 hours after mixing, 60 lbs.; 6 days, 120 lbs." The tensile strengths required by this specification are very low. For a 24-hour test, at least 150 pounds should be required. The ordinary time test is 7 days, and should show a strength of 350-400 lbs. Just why 6 days is specified in this case, and the strength of only 300 pounds required, does not seem clear.

"The cements will be tested by the Architect from time to time; and if the same prove to be of inferior quality, the cement of such brands will be rejected, and all work built of such cement will have to be removed and rebuilt.

sand is to be of the very best quality, clean, sharp, grit sand, entirely free from loam, to be properly screened." "The very best quality" of sand is well standardized; but a better specification of sand, which is more comprehensive, espe cially in regard to loam, would be as follows: "All sand shall be clean, sharp, grit, or fresh-water sand of uniform texture and free from all impurities. It shall show no loam and not more than 5 per cent by volume of silt, after being shaken in water and allowed to settle." A sand specification can easily be so strict as to add a great deal to the cost of the work, without corresponding advantage.

"Cement

mortar is to be made in the following manner: The parts of ce ment and sand are to be mixed dry, carefully and thoroughly; to this a sufficient quantity of water only to make it of good working consist ency is to be added. Mortar is to be made in

no greater quantity than is required for the work on hand; and no excess that !lay have been left over night, or that has been mixed more than two hours, is to be retempered or used in any way.

"Cement

mortars are to be mixed as follows: "Rosendale cement mortar—one barrel of ce ment and two barrels of sand.

"Portland cement mortar—one barrel of ce ment and three barrels of sand." Literally, under this, no lots requiring less than one barrel of cement can be mixed.

In the last two clauses, no statement is made as to the size of barrel, whether the cement is to be measured packed or loose, or how to be measured. It is a common speci fication at the present day to state that a barrel of Portland cement shall be consid ered as 380 pounds net.

"In all cases the sand used for cement mor tar is to be measured in barrels; this must be strictly carried out, and no deviation will be allowed.

"Any work built with cement mortar not properly mixed, or in whole or in part retem pered, will be rejected.

"La Farge cement mortar is to be made of one part of La Farge cement, and three parts of clean sharp white sand, to which one part of lime putty, properly slaked and run, is to be added.

"Concret.

The concrete is to be made of one part of cement and three parts of sand, mixed as before specified for cement mortar, to which add four parts of clear broken stone, broken so as to pass in any way through a 2-inch ring. Concrete is to be mixed in no greater quantity than can be used immediately; and no excess that has been left over night, or that may have been mixed more than two hours, is to be retempered or used in any way." With all the wealth of literature upon the mixing of concrete, and with all the excellent examples of specifications for such work that are in existence, it is indeed surprising to find such a clause as this in supposedly up-to-date specifications. In the first place, the mortar specification is in itself incomplete, but is re ferred to in the concrete specification; and no specification is made as to how or when the stone shall be added, or how it shall be mixed. According to the letter of this spe cification, as the mortar is mixed the required quantity of stone might be dumped in the midst of it and immediately shoveled into place or into some vehicle for transportation, without becoming in any sense of the term a true mixture of concrete. Perhaps the archi tect intends the very word "concrete" to im ply what the mixture shall be like; but here again there is such a variety of interpreta tions that a crafty contractor might want to make almost anything go.