The concrete to be used for masonry walls or other special structures as ordered shall be of the class designated and shall conform to the respective specifications therefor under the head of "Concrete" Items 30, 31, 32.

Proportioning and Mixing. - Proportioning and mixing shall conform to the respective specifications therefor under head of "Concrete" Items 30, 31, 32.

Consistency. - The material shall, in all cases, unless otherwise ordered, be mixed wet enough to produce a concrete that will flow readily which can be handled without causing a separation of the coarse aggregates from the mortar.

Placing. - After mixing, the concrete shall be deposited in place immediately. No retempering will be allowed, and concrete which has not been placed within 30 minutes after mixing shall be rejected and removed from the work. Concrete shall be deposited as nearly as possible in its final position. Rehandling of concrete after it has been deposited within the forms shall not be permitted. The concrete shall in no case be dumped or dropped from any great height. Each batch of concrete shall be spread in layers not exceeding four (4) inches in thickness. 'As Boon as one layer is completed the next layer above must be started at once, and the work continued without interruption. As far as possible, the work shall be monolithic Concrete shall be placed as continuous work between such planes and elevations as the Engineer may direct. When another layer of concrete is placed on one that has already set, the surface of the old concrete must be cleaned of all loose material, then roughened, wetted, and slushed with neat cement, before placing the new layer; or the bond shall be made by the acid or other approved process, if so directed by the Engineer. When it is necessary to make a joint in monolithic concrete, it shall be made by means of a stop-board placed in a vertical position and containing a key on the side next the concrete first placed. When the stop-boards are removed, the bond shall be made as above described. No tapered or wedge-shaped slope shall be used. Care must be taken to avoid getting dirt or other foreign matter on concrete surfaces on which other concrete is to be placed, or which has not set. At all stages of the work concrete and mortar must be kept entirely free from dirt of all kind, and if unavoidably mixed with dirt, shall be removed and replaced to the entire satisfaction of the Engineer.

Ramming. - Rammers for use with wet concrete shall be composed of thin blades of steel or iron, about four (4) inches wide. With these the concrete shall be thoroughly spaded and churned to remove all entrained air, and the concrete shall be pushed in forms and into all small openings. Ramming drier mixtures shall be thoroughly done with rammers of such shape and weight as directed, but in no case shall the concrete be mixed dry enough to require very heavy rammers.

Finish. - This shall be done by careful spading and puddling the plastic concrete for which special tools shall be provided. This must be done with great care that subsequent amount of pointing necessary will be a minimum. Immediately after the forms have been removed, chip off any ridges due to cracks and joints in the lumber, and point the surface with mortar of same proportions as that used for concrete until it is even and smooth*. All surfaces must present a neat, even and smooth appearance, satisfactory to the Engineer, such appearance to be obtained by rubbing with a carborundum brick if deemed necessary by the Engineer.

Forms. - All forms for moulded concrete work shall be constructed of sufficient strength to obtain the necessary rigidity to prevent any motion of the forms while concrete is being placed, and must be strong enough to carry any load which may come upon the concrete within thirty (30) days from the date of placing the concrete. Before work is commenced the Contractor shall submit detail plans of the method of constructing forms to the Engineer, but the submitting of such plans will not relieve the Contractor of any responsibility should any fault appear during the construction.

Forms shall, in general, be composed of tongue and grooved sheeting if 7/8 - inch sheetings is used, or carefully matched stuff if heavier sheeting is used. Each plank must be of uniform width, fastened to the studding in true horizontal lines, ends and edges being carefully butted together. They must be as nearly as possible water-tight, and must be surfaced on the side next the concrete for all surfaces which will be exposed in the finished work.

Planking once used in forms shall be cleaned before using again. Deformed, broken or defective forms shall be removed from the work. Forms shall be constructed by experienced and capable workmen only, and must be true to line and grade. They shall be substantial and unyielding, of exact dimensions for the structure to be built, and of first-class workmanship throughout. The frame or studding must be properly braced or tied together by means of wire or rods.

The surfaces next the concrete will be oiled just after being built and oiled again just previous to placing the concrete. Forms used a second time must be carefully cleaned and oiled again. The oil to be used shall be paraffine oil, thick and heavy enough to act as a filler.

Forms must be kept moist to prevent shrinkage, as directed by the Engineer. All forms shall be so constructed as to be readily cleaned. Great care must be taken to clean sawdust, dirt or debris from the forms just before placing the concrete, and whenever necessary forms must be cleaned out with steam-jet or equally effective means satisfactory to the Engineer. Forms shall not be removed from the concrete in less than --------- (------) days. No forme whatever will be removed at any time without first notifying the Engineer, and he may increase the time for forms to remain in place if deemed necessary. The notification given the Engineer shall not be considered to relieve the Contractor of full responsibility for the construction and removal of forms.

All forms must be so designed so that they may be removed without damage to the concrete.

All projecting wires and bolts, or other devices that may be used for holding the forms in place and that pass through the concrete, must be cut off at least one inch beneath the finished surface and the ends covered with cement mortar of same mix as used in the body of the work.

The Contractor shall furnish a sufficient number of forms so that the work can be prosecuted rapidly, and if at any time the work is not proceeding at a rate sufficient, in the opinion of the Engineer, to complete the work in a reasonable time, a greater number of forms shall be constructed if required. If the Contractor desires, he may use steel forms in place of wood forms. Steel forms must meet the approval of the Engineer.

Weep holes and expansion joints shall be provided as ordered. All walls or other special structures shall be constructed as shown on the plans or ordered.

Payment. - The concrete masonry will be paid for by the cubic yard, as provided for under "Concrete," Items 30, 31 and 32, except that in measuring the volume no deduction will be made for weep holes.