PART 1 - GENERAL
1.01 SECTION INCLUDES
Structural Portland cement concrete and reinforcing for manholes and intakes for sanitary and storm sewer systems, and other structures such as concrete thrust blocks and sewage air release pits as designated by the Jurisdictional Engineer.
1.02 DESCRIPTION OF WORK
A. Construct Portland cement concrete structures for sanitary and storm sewers.
B. Reference is made to the Iowa Department of Transportation
Specifications for Highway and Bridge Construction, Series 2001, and all
current General Supplemental Specifications and
Materials Instructional Memerandum by the term "Iowa DOT Specification Number
Specifications" and/or " I.M. Number
Iowa DOT I.M.".
A. Submit under provisions of Division 1.
B. Shop drawings of steel reinforcement, showing sizes, lengths, bends, and counts, if required.
C. Concrete mix design, if required by Jurisdictional Engineer.
D. Sample test results and certifications.
E. Certification that materials being provided meet the requirements of these specifications or that alternate materials or substitutions have received written approval of the Jurisdictional Engineer.
F. Project Record Documents.
G. Upon requests the Contractor will provide Material Certifications to the Jurisdictional Engineer.
A. Use only materials conforming to these specifications unless permitted otherwise by Jurisdictional Engineer.
B. Obtain written approval of Jurisdictional Engineer for all substitutions prior to use.
1.05 DELIVERY, STORAGE, AND HANDLING
A. Deliver only materials that fully conform to these specifications and for which submittals have been provided to Jurisdictional Engineer and approved for use.
B. Store and handle materials to avoid damage. Store reinforcing steel only on pallets or lagging. Replace any damaged materials. Remove damaged materials from the site.
C. Aggregate storage and concrete transport shall follow Section 7010, 1.05.
A. Construction Sequence:
Schedule concrete placement to coordinate with other work, such that trenching, backfilling and other work can proceed in an orderly manner and to provide the greatest protection for new work.
B. Conflict Avoidance:
1. Expose potential conflicts such as utility lines and drainage structures in advance of construction. Verify elevations and locations and verify clearance for proposed construction.
2. Complete elements of work which can affect line and grade in advance of pipe construction unless noted on plans.
3. Notify Jurisdictional Engineer of conflicts discovered or changes needed to accommodate unknown conditions.
1.07 SPECIAL REQUIREMENTS
A. Stop Work: Stop work and notify Jurisdictional Engineer immediately if contaminated soils, historical artifacts or other environmental or historic items are encountered.B. Conform to local, state and federal requirements.
C. Restrictions: Restriction on operations shall follow Section 7010, 1.07.
1.08 MEASUREMENT FOR PAYMENT
The cost for concrete and reinforcing in the construction of manholes, lift stations, and sewage air release pits for sanitary sewer systems, and manholes and intakes for storm sewer systems, or other special structures, will not be measured separately but will be considered incidental to intakes and manholes or other concrete structures as described in this specification document, including sampling and testing as specified in Section 6010, 3.08.
PART 2 - PRODUCTS
2.01 CONCRETE MATERIALS
A. Portland Cement:
1. ASTM C 150, Type I or Type III when specified.
2. Air entrained per ASTM C 260.
3. Iowa DOT Class C concrete unless otherwise specified in the contract documents.
1. Per ASTM C 33.
2. Coarse and fine aggregate shall follow Section 7010, 2.02.
C. Water: Follow Section 7010 2.02, E
D. Liquid Admixtures for Portland Cement Concrete:
a. Meet requirements of AASHTO M 154 for air entraining mixtures.
b. Meet requirements of AASHTO M 194 for other liquid admixtures.
c. Submit tests by a recognized laboratory for Jurisdictional Engineer approval.
d. Admixtures containing more than 1% chloride ions shall not be allowed unless approved by Jurisdictional Engineer.
e. Inspection and acceptance of liquid admixtures will be in accordance with Iowa DOT Materials I.M. 403
2. Air Entraining Admixtures: Provisions shall be made to stir, agitate, or circulate air entraining admixtures prior to use to insure a uniform and homogeneous mixture.
3. Retarding and Water Reducing Admixtures
a. Shall be compatible with air entraining agent.
b. Shall be introduced into the mixer after all other ingredients
c. Agitate prior to and during use in accordance with Iowa DOT Materials I.M. 403
d. Dosage rate shall be applied to both cement and fly ash when used.
4. Other Admixtures: Other admixtures may be used with the approval of the Jurisdictional Engineer in accordance with the manufacturer's recommendations.
2.02 CONCRETE QUALITY
A. Compressive Strength: Minimum 4,000 psi at 28 days.
B. Water-Cement Ratio: Follow Section 7010, 2.03.
C. Air Content: The intended air entrainment is 6.0%. To allow for loss during placement, the air content of fresh, unvibrated structural concrete shall be 6.5%, as a target value, with a maximum variation of plus or minus 1.0%.
D. Slump: Structural concrete shall be placed with a slump between 1 inch and 3 inches as a target range, allowing a maximum of 4 inches unless specifically modified by the Jurisdictional Engineer.
E. Admixtures: Per manufacturer’s recommendations.
A. Reinforcing Steel:
1. Use deformed bars.
2. Epoxy coated deformed bars apply only when specified.
3. Billet steel; ASTM A 615, Grade 60.
4. Fabricate and bend, per approved submittals or Plans.
5. Fabricate all bars prior to delivery to site unless field bends are required.
B. Wire Fabric:
1. Per ASTM A 185.
2. Size and mesh; as shown on Detailed Drawings or on Plans.
3. Placement; as shown on Detailed Drawings or on Plans.
4. Joints; lap not less than 6 inches.
2.04 CEMENT MORTAR: Mix in the following portions:
A. Portland Cement: Type I; 10 Parts
B. Mortar Sand: 20 Parts
C. Lime, Hydrated: 3/4 to 1 Part
PART 3 - EXECUTION
A. All cast in place manholes and structures shall be formed on both the inside and the outside face above the base. No earth excavation next to the proposed manhole shall be used as forming.
B. Use metal or plywood-lined forms for exposed surfaces.
C. Erect and secure forms to true line and grade.
D. Coat forms with non-staining mineral oil before placing reinforcing. Do not apply oil to surfaces to which concrete must be bonded.
E. Use 3/4 inch bevel for exposed corners, unless otherwise required.
3.02 REINFORCING STEEL
A. Remove dirt, scale and other materials that might impair concrete bond.
B. Place reinforcement where shown. Space bars properly and secure in position.
C. Reinforcement for slabs; support with chairs or bolsters. Do not use wood, bricks, stones or other foreign materials.
D. Lap bars 36 diameters, except as otherwise shown.
A. Provide accurate control for measuring materials.
B. Concrete, as discharged from the mixer, shall be uniform in composition and consistency. Each batch of concrete shall be thoroughly discharged from the mixer before the next batch is introduced. Upon cessation of mixing for any considerable length of tie, the mixer shall be thoroughly cleaned and flushed with water.
C. Ready-Mixed Concrete: conform to ASTM C 94.
A. Clean and dampen forms, reinforcing steel and embedded items.
B. Prevent segregation during placement. Do not allow concrete to fall more than 4 feet from placement chute to final position.
C. Place concrete continuously in each section until complete. Do not allow more than 30 minutes between depositing adjacent layers of concrete within each section.
D. Thoroughly compact, puddle and vibrate concrete into corners and around reinforcing and embedded items. Vibrate sufficiently to work concrete into crevices and around steel. Refer to Iowa DOT 2403.09.
E. Place sections of concrete in a sequence which eliminates the effect of shrinkage to the greatest extent practicable.
F. Concrete shall not be placed when the air temperature is less than 40 degrees Fahrenheit without the approval of the Jurisdictional Engineer. Refer to Iowa DOT 2403.11.
A. Refer to Iowa DOT 2403.21.
B. Use rough form finish to areas not visible to the public.
C. Use smooth form finish for areas visible to the public.
D. Use broomed finish for slabs, except as noted on Plans or Detailed Drawings.
3.06 STRIPPING AND CLEANING
A. Remove forms for manhole and intake walls and tops according to Iowa DOT 2403.18.
2. When allowed by the Jurisdictional Engineer, compressive strengths as six times the stated flexural strengths may be used in determining concrete strength of structure roofs.
AB. Chip out and repair any honeycomb areas per direction of Jurisdictional Engineer. BC. Break back form ties and fill holes with portland cement mortar. CD. Remove flashing and thin webs.
A. Refer to Iowa DOT 2403.10.
B. Apply curing system immediately after finishing or stripping of forms, as applicable.
C. Slabs on grade, visible to the public; use only curing compounds meeting ASTM C 309, Type 1-D or Type 2.
3.08 Exterior Loading
A. Restrict loads on concrete, other than the load caused by the weight of the concrete itself, according to Iowa DOT Section 2403.19.
B. When allowed by the Jurisdictional Engineer, compressive strengths at six times the stated flexural strengths may be used.
A. Provide required testing by a testing service approved by Jurisdictional Engineer, unless such services are provided by Jurisdiction.
B. Review and
check‑test proposed mix design when required by Jurisdictional Engineer.
C. Obtain production samples of job‑delivered concrete mix after any needed water has been added and the concrete remixed.
D. Mold and cure three specimens per ASTM C 31.
E. Strength Testing: Unless otherwise specified in the contract documents strength testing will be the responsibility of the Contractor by a certified testing service.
1. Test specimens in accordance with ASTM C 39. Test one sample at 7 days for information. Test two samples at 28 days. The acceptance test results shall be the average of the compressive strength of the two specimens tested at 28 days. If one of the 28 day samples manifests evidence of improper sampling, molding or testing, it shall be discarded and the strength of the remaining sample shall be considered the test result.
2. Make at least one strength test for each 100 cubic yards or fraction thereof, and at least one test for each structure. When the total quantity is less than 50 cubic yards the strength tests may be waived by the Jurisdictional Engineer.
F. Slump Testing: Unless otherwise specified in the contract documents testing will be by the Jurisdictional Engineer. Determine slump of concrete sample for each strength test and whenever consistency of concrete mix appears to vary, using ASTM C 143.
G. Air Testing: Unless otherwise specified in the contract documents testing will be by the Jurisdictional Engineer. Determine air content of concrete sample for each strength test in accordance with either ASTM C 231, ASTM C 173, or ASTM C 138.
END OF SECTION