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Final Consolidation and Finishing
Transcript of Final Consolidation and Finishing
1. Addition of water to the surface of concrete in order to assist in finishing operations should not be permitted.
2. The concrete placed adjacent to joints shall be compacted and firmly set without voids or segregation under and around the load transfer devices, joint assembly units, and other features designed to extend into the pavement.
4. If the uninterrupted operation of finishing machine over beyond the joints causes segregation of concrete, and misalignment of the joints, the finishing machine should be stopped when the front screed is approximately 20 centimeters from the joint.
1. After the final finished, but before the concrete has taken its initial set, the pavement edges along its side of the slab and all joints, transverse construction joints, and emergency construction joints, should be worked with an approved tool and rounded to the radius required.
2. Any tool marks appearing on the slab, adjacent to the joints should be eliminated by brooming the surface. But in doing so, the rounded slab corner should not be disturb. All concrte on top of the joint feelers should be removed completely.
3. All joints are tested with a straight edge and corrected if one edge of the joint is higher than the other before the concrete be set.
5. The front screed should be lifted and set directly on top of the joint and the forward motion of the finishing machine is resumed.
6. Thereafter, the finishing machine may be run over the joint without lifting the screeds, if there is no segregated concrete immediately between the joint and the screed or on top of the joint.
4. If the surface texture is belt finished, after straight edging and the water sheen has practically disappeared, and just before the concrete becomes non plastic, the surface is belted with 2-ply canvas belt not less than 20cm. Wide and at least 100cm. Longer than the pavement width.
5. Hand belt must have suitable handles to permit a controlled uniform manipulation. The belt is operated with short strokes transverse to the centreline with a rapid advance parallel to the centreline.
the concrete is distributed and spread as soon as placed. It is struck off and screened by an approved finishing machine. The machine goes over each area of pavement as many times and at such intervals as necessary to give the proper compaction and leave a uniform texture surface.
1. Excessive machine operation over a given area should be avoided. The top of the forms should be kept clean by an effective device attached to the machine and the travel of the machines on forms should be maintained true to grade without wobbling or other vibration tending to affect the precision finish.
2. During the first past of the finishing machine, a uniform ridge of concrete should be maintained ahead of the front screed in its entire length.
3. If uniform and satisfactory density of the concrete is not obtained by the vibratory method at joints along the forms of structures, and through out the pavement, the contractor will be required to furnish the equipment and method that will produce pavement conforming to the specifications.
Hand finishing methods may be used under the following conditions:
1. In the event of mechanical equipment breakdown hand methods may be used to finish the concrete already deposited on the grade or form.
2. In a narrow width or areas of irregular dimensions where operations of the mechanical equipment are impractical, hand methods may be used.
3. Concrete as soon as placed is struck off and screeded by an approved portable screeder.
4. Consolidation should be attained by the used of suitable vibrator or other approved equipment.
5. On finishing operations, the screed is moved forward on the forms with a combined longitudinal and transversal shearing motion.
6. Movement is always in the direction where the work is progressing and manipulated that neither end is raised from the side forms during the striking off process.
1. After the concrete has been struck off and consolidated, it is further smoothen, trued and consolidated by means of longitudinal float, either by hand or by mechanical method.
2. The hand operated longitudinal float should not be less than 3.6 meter long and 15cm wide properly stiffened to prevent flexibility and warping.
3. The longitudinal float is operated from a footbridge resting on the side forms and spanning but not touching the concrete.
Straight Edge Testing
1. After the floating work and excess water removed, while the concrete is still in plastic condition, the surface of the concrete is tested for correctness by 3.0m long straight edge bar.
2. The straight edge bar is held in contact with the surface in successive positions parallel to the road centerline and the whole area gone over from one side of the slab to the other as necessary.
3. Advances along the road should be in successive stages of not more than one half the length of the straight edge bar.
4. The surface across the joints must strictly meet the requirements for smoothness. The straight edge testing should continue until the entire surface is found to be free from humps and noticeable departures from the straight edge bars.
4. The movement ahead along the centerline of the pavement should be in successive advances of not more than one half length of the float. Any excess water or soupy materials is wasted over the side forms on each pass.
5. The float from where the mechanical float operates should be accurately adjusted to the required crown and float also accurately adjusted and coordinated with the transverse finishing machine so that small amount of mortar is carried ahead of the float at all times.
6. The float should pass over each are pavement at least 2 times. Excessive operations over certain area should not be permitted. Any excess water or soupy material should be wasted over the side forms on each pass.
1. If the surface texture is broom-finished, it should be applied when the water sheen has practically disappeared. The broom should be drawn from the center to the edge of the pavement with adjacent strokes slightly overlapping.
2. The brooming operation is executed by producing uniform appearance of corrugations produced in the surface not more than 1.5 mm depth.
3. Brooming should be completed before the concrete is in such condition that the surface will be unduly roughened by the operations.
6. If the surface texture is drag finished, use a drag, which consists of a seamless strip of damp burlap, or cotton fabric, which will produce a uniform gritty texture after dragging it longitudinally along the full width pavement.
7. For pavement 5 meters or more in width, the drag is mounted on a bridge, which travel on the forms.
8. The drag shall consist of not less than 2 layers of burlap with the bottom layer approximately 15 centimeter wider than the layer.
Edging at Forms and Joints
1. The pavement surface is tested with a 3m straight edge or other specified device. Areas showing high spots of more than 3mm but not exceeding 12mm in a 3m span is marked and immediately ground down with an approved grinding tool to an elevation where the area or spot will not show surface deviations in excess of 3mm when tested with a 3m straight edge.
2. Where the departure from correct cross section exceeds 12mm, the pavement should be removed and replaced by the contractor at his expense.
3. Any area or section that was removed should not be less than 1.5m in length and not less than the full width of the lane involve.
4. When it is necessary to removed and replaced a section of the pavement, any remaining portion of the slab adjacent to the joints that is less than 15m in length should be removed and replaced.