118

D.—l

Basis of Payment. —Tho cost of all material and the furnishing of all labour, tools, implements, equipment, and supplies, and the doing of all. work incidental to placing the side forms, shall be considered as included in the price paid for pavement, and no additional allowance will be made therefor. Water-supply. Description. —Before placing surfacing or paving the contractor must develop a good and sufficient supply of water, and have it available along the line of his work in a pipe-line. The supply should be adequate to supply sufficient water for all purposes for which water is needed, including the sprinkling or flooding of the earth grade, for use in making subgrade, for sprinkling surfacing, for use in mixing concrete, and for use in watering the checks used to cure concrete pavement, which shall bo kept flooded for two weeks after they are built. Pipe-line. —In constructing concrete pavement where a mixer is used the capacity of which is four sacks of cement or over per batch, it is recommended that the pipe supplying water to the mixer have the following dimensions : 60 per cent, of the lino have a minimum diameter of 3in., this part of the line connecting with the pump or source of the water-supply ; the remaining 40 per cent, of the line have a minimum diameter of 2 in. A pipe-line having a minimum diameter of less than 2 in. will not be considered as satisfactory or as complying with the intent of these specifications. Faucets and other connections shall be provided at suitable intervals. Force-pumps shall bo installed where necessary in order to provide ample pressure of water at all points along the line. A deficiency of water-supply will be considered at any and all times a sufficient cause for the delay or shutting down of the concrete mixer, In the case of a deficiency of water-supply the water available shall be devoted to curing the concrete already placed. Placing Concrete Pavement. Welting Subgrade. —lmmediately before placing the concrete, the earth subgrade and the side forms shall be thoroughly watered by a hose with a spray nozzle to the extent that the subgrade will not absorb moisture from the concrete that is placed thereon. There shall be no pools on the subgrade caused by using too much water. Nail Templet. —The contractor shall use a nail templet behind tho mixer and in front of the placing of concrete, and all high portions of the subgrade shall be made to conform to it. The filling in of low spots in the subgrade with loose material will not be permitted. Placing.— Upon the subgrade as hereinbefore specified, and while it is thoroughly damp and firm, there shall be placed a concrete pavement of the thickness, width, and cross-section shown on the plans. Concrete for pavement shall be Class A concrete, consisting of the ingredients and mixed as provided in these specifications under the heading " Portland Cement Concrete." The concrete shall be deposited to the required depth for the, entire width between headers in successive batches, and in a continuous operation. Unsatisfactory Concrete.— All concrete shall be used while fresh and before it has taken an initial sot. The retempering with additional water of any concrete that has partially hardened will not be permitted. Any batch showing improper proportions of materials or a surplus cr deficiency of water, and which does not have the proper consistency when it comes from the mixer, -shall not bo used in the pavement. Cross-header. —Whenever necessary to stop the mixer the work shall be finished square across the pavement by use of a special header 4 in. in width conforming to the shape of the pavement. This header shall be set fin. below tho surface of tho pavement, in order to ensure the construction of a smooth-riding joint. Protecting Concrete Pavement. —ln all. work done under this contract the contractor shall adequately protect the surface of tho concrete pavement against all damage and markings both from foot and other traffic. At all places where it is necessary to maintain public or private crossings over the pavement the contractor shall, at his own expense, provide and maintain bridges or other devices such as will prevent the damage or marking of the concrete pavement. Finishing Concrete Pavement. Tamping. —The tamping and finishing of the concrete pavement shall be accomplished by the use of an approved automatic tamping and finishing machine, operated by a man experienced in the handling of the particular make of machine in. use. The. operation of tamping shall produce a satisfactory and high-grade quality of concrete, with the surface of the pavement smooth and uniform, true to grade and cross-section, and free from all hollows and inequalities. During the process of tamping and finishing concrete, if any yielding takes place in the headerboards they shall be immediately stiffened by additional stakes until they stand the weight of the tamper without yielding. After the concrete has been struck off and tamped it shall not be disturbed by walking upon it or by any other cause. Grades over 5 per Cent. —On grades in excess of 5 per cent, a light strike-board shall follow from 25 ft. to 50 ft. back of the heavy strike-board or tamper, and shall be used in the same way, so as to remove waves caused by the flow of the concrete. Testing Templet. —The templet and tamper boards shall at frequent intervals of time be tested for shape. In making these tests the templet and tamper boards shall be placed in the same relative position that they occupy when in use, and in no case shall they be tested when turned upside down.