SECTION 06100 - CONCRETE AND CONCRETE STRUCTURES

r water shall be such as to keep as much as possible of the concrete being placed out of direct contact with the water so as to avoid any rapid movement or agitation of the exposed surface.
The work shall, where possible, be carried out in one operation. Where this is impracticable, laitance, washed-out aggregate or foreign matter, which may have accumulated on the previously placed concrete, shall be completely removed prior to additional concrete being placed. This concrete shall then be placed directly on the cleaned surface.
Tremie pipes shall be smooth bored watertight fitted with quick release joints and have an adequate cross section for the size of aggregate to be used. Aluminum pipes shall not be used.
Bottom opening skips shall be straight sided, perfectly smooth and fitted with externally operated bottom opening double doors and overlapping canvas flaps.
The Contractor shall submit and obtain the approval of the Engineer for his detailed proposals for concreting under water. 
Where concrete is to be placed in or under water, the actual mix proportions and selection of aggregates shall be such as to ensure a resulting concrete with good flow and cohesion characteristics.
The cement content shall be 25 percent greater than for a comparable mix for use in dry conditions. The minimum works cylinder strength for all concrete shall be approved by the Engineer for the comparable mixes for use in dry conditions.
Waterstops
Waterstops shall be furnished and installed in accordance with the details indicated on the Drawings, the provisions in this General Specification and as directed by the Engineer.
Waterstops shall conform to the cross section and to the minimum dimensions indicated on the Drawings.
Waterstops shall be manufactured either from neoprene or from polyvinylchloride (PVC), at the option of the Contractor.
No splices will be permitted in straight strips. Strips and special connection pieces shall be well cured in a manner such that any cross section shall be dense, homogeneous and free from all porosity. All junctions in the special connection pieces shall be full molded. During the vulcanising period the joint shall be securely held by suitable clasps. The material at the splices shall be dense and homogeneous throughout the cross sections.
If after placing concrete, waterstops are materially out of position or shape, the surrounding concrete shall be removed, the waterstop reset, and the concrete replaced, all at the Contractor’s expense.
Field splices for neoprene waterstops shall be either vulcanized, mechanical, using stainless steel parts; or made with a splicing union of the same stock as the waterstop, at the option of the Contractor.
Field splices for polyvinylchloride waterstops shall be performed by heat sealing the adjacent surfaces in accordance with the manufacturer’s recommendations. A thermostatically controlled electric source of heat shall be used to make all splices. The heat shall be sufficient to weld but not char the plastic.
Waterstops when being installed shall be cut and spliced at changes in direction as may be necessary to avoid buckling or distortion of the web or flange.
Field splices shall develop watertightness equal to that of the unspliced material and have a tensile strength of not less than 50 percent of the unspliced material.
Tolerances
General
The tolerances listed in Tables A and B are the allowable deviations from the dimensions shown on the drawings. These tolerances will be a basis for acceptance of the work.
Soffits
The soffits of arches, box girders, beams and deck edges shall be continuous curves or straight lines as shown on the drawings, free form all visible irregularities.
Table A
General Tolerances
Item
Tolerances (mm)
Placing of reinforcement
 controlled by cover; half bar diameter otherwise
Placing of post-tensioning sheathing
5
Concrete cover
0 to +5
Table B
Item
Tolerance (mm unless shown otherwise)
Footings
Plan dimensions
Formed footings and pile caps
-15 to +50
Unformed footings (when approved by the Superintendent)
0 to +150
Thickness
< 300 mm
-5 to +25
> 300 mm
-10 to +50
Top of footing or pile cap reduced level
-25 to +25
Departure from the plan position in any direction
50
Cylinders
Variation from the vertical
25 mm in 3m
Departure from the plan position in any direction
75
Variation in Cross Section of Columns, Piers, Crossheads, Slabs, Walls, Beams and Similar Parts (excluding deck slabs and end posts)
< 3 m
-5 to +15
> 3 m
-10 to +25
Variation of Cross Section of End Posts
-5 to +5
Deck
Thickness of Deck Slabs (excluding allowance for correction of camber or hog)
0 to +10
Deck surface reduced level
-10 to +10
Deck Joints
Width of slot
-3 to +3
Variation from Vertical or Specified Batter of Columns, Piers, Walls, Handrail Posts and Arrises
Unexposed concrete
10mm in 2.5 (1/250)
Exposed concrete
5mm in 2.5m (1/500)
Variation from Grades Indicated on Drawings for Railings, Kerbs and Arrises
2.5 mm in 2.5 m (1/1000)
Reduced Level of Tops of Crossheads and Piers
With pedestals
-10 to +10
Without pedestals
-5 to +5
Difference in Level across width of crosshead
5
Bearing pedestals
Reduced level
-2.5 to +2.5
Variation from grade across the width of individual pedestals shall not exceed
1 in 200
Deviation from flat surface
+1.0 to –1.0
Departure from Plan Position at any Level
Columns, Piers, Walls, Crossheads, Beams, Slabs, Kerbs, Railing and other similar parts
25
Relative displacement of adjoining components shall not exceed
10
Departure from Alignment
Rows of columns, faces of piers or walls
10
Handrails, Faces of hand rail posts, Kerbs
5
Maximum Allowance for Irregularities in Exposed Concrete Surfaces
Sections less than 1m in dimension when measured with a straightedge across the dimension of the section
2.5
Sections greater than 1m in dimension when measured with a straightedge across the dimension of the section, except that when sections are greater than 2.5 m in dimension, a 2.5 m straightedge shall be used
5
Irregularities in Railings
2.5 mm in 2.5m
Slab Surface Finish
5mm in 2.5m
Precast Concrete Elements
General 
The contractor shall provide and install the precast constituents and components, complete, furnishing all materials, labor and equipment and performing all required work as required by Drawings, as specified herein, other applicable Specification sections and as directed by the Engineer.
The precast constituents and component work shall include, but not by way of limitation, the furnishing and installing of the precast constituents and components, necessary grout and grouting and all appurtenances required for their proper installation.
Materials
Concrete materials incorporated in the fabrication of precast constituents and components shall comply with the applicable requirements of this Subsection section as well as other applicable Specification sections and shall be Class of concrete as noted on the drawings or as directed by the Engineer. 
Grout shall be an approved, flowable, non-shrink, non-metallic grout containing sulfate resistant cement. The grout shall have a minimum compressive strength of 210 kg/cm2 at an age of 24 hours when tested using applicable portions of ASTM C109. The grout shall show no expansion after final set takes place when tested in accordance with ASTM C827. The grout shall have as initial setting time of not less than 45 minutes. 
Fabrication
Precast items shall be lifted and otherwise handled to prevent damage. Any damage to precast items that occurs during transportation or placement shall be inspected by the Engineer. The Engineer may be rejected damaged precast items if (in the opinion of the Engineer) such damage will adversely effect the strength and/or the appearance.
Measurement and Payment
General 
Measurement and payment for the items of concrete construction will be as described herein and as included in the Bills of Quantities. The work included under the respective items enumerated in the Bills of Quantities shall include all labor, materials, tools, equipment and appurtenances to complete the respective Items.
The formwork, curing, joints, concrete finishing, placing concrete, testing and waterstop, shall be considered a subsidiary obligation to applicable items of the Bill of Quantities and no separate measurements and payment will be made to these items.
For precast concrete items, including those that are addressed in other specification sections measurement and payment will be by the number and type furnished, erected and accepted in accordance with specification requirements and requirements of the Drawings. All work required for the manufacture and erection shall be included in the rates as indicated in the Bill of Quantities.
Measurement 
Measurement for the various Classes of concrete and in the various locations will be by the cubic meter in place as indicated on the Drawings and as described in the Bill of Quantities. Measurement will be made to the neat lines of the structures as indicated on the Drawings. No deduction will be made for the volume occupied by reinforcement steel bars, structural items or other items embedded in concrete.
Payment
Payment for the items of concrete (of the various Classes of concrete and the various locations as indicated on the Drawings, as described in the Bill of Quantities) shall be paid for in accordance with applicable Unit Prices as indicated on the Bid Price Schedule. Payment shall be considered as full compensation for all labor, materials, tools, equipment, formwork and appurtenances to complete the concrete items.
Pay Item
Description
Unit
06100-1
Class A Concrete
m3
06100-2
Class B Concrete
m3
06100-3
Class C Concrete
m3
06100-4
Class D Concrete
m3
06100-5
Class E Concrete
m3
06100-6
Class F Concrete
m3
06100-7
Class G Concrete
m3
06100-8
Class H Concrete
m3