101 SECTION 207 DESCRIPTION
207.01.01 General. This work consists of placing and compacting backfill or granular backfill material in
excavations for bridges, retaining walls, headwalls, culverts, and other structures. This work also consists of furnishing and placing slurry cement backfill as shown on the plans, or as an alternative to backfill or granular backfill. Applications include use as structural fill, pipe encasement, or pipe and trench backfill as approved. For placement adjacent to bri dge structures, prior approval by the Bridge Engineer is required. MATERIALS
207.02.01 General. Material shall conform to the following Subsections:
Backfill ................................ ................................ ................................ ................................ ................................ .... Subsection 704.03.10 Granular Backfill ................................ ................................ ................................ ................................ ...................... Subsection 704.03.11
207.02.02 Slurry Cement Backfi ll. Slurry cement backfill shall consist of a workable mixture of various
combinations of aggregate, cement, mineral admixtures, liquid admixtures, and water. Aggregate shall consist of a concrete, grout, or mortar aggregate as specified in Section 706. Cement shall meet the requirements of Section 701. All approved cement types and blended cements or combination thereof may be used. Mineral admixtures shall meet the requirements of Section 702. For ap proval, submit a mix design stamped by a Professional Engineer registered in the State of Nevada to ensure accordance with performance specifications listed herein. The mix design shall include a list of all ingredients, the source of materials, gradations of aggregates, types of admixtures, dosage rates, and batch weights. A change in the source of materials, gradation, or addition or deletion of admixtures may necessitate a new mix design and trial batch. Provide test data from a n accredited laborator y showing that the proposed mix design meets the performance specifications herein. Accreditation shall be obtained from the American Association of State Highway and Transportation Officials (AASHTO) or the American Association for Laboratory Accreditation (A2LA). A mix design having prior acceptance by the Department, local municipalities, or utility companies may be approved if documentation of test results and past field performance is provided. Submit slurry cement mix designs conforming to one of the following classes of flowable fill, A or B, de pending on the application. The type of application shall be shown on the plans or be as determined by the Contractor and approved. Determine proportioning as shown on the approved mix design. The trial batch and subsequent placements shall produce a mix c onsistency that will result in a flowable self -leveling product at the time of placement. Excavatable Non-Excavatable Class A B 28 Day Strength .......................... 340-1,400 kPa (50 -200 psi) ............. 1,400 -6,900 kPa (200 -1,000 psi) Air Content ................................ ............. 5% Min. ................................ ............... 5% Min. Subsidence ................................ ............ 1% Max. ................................ ............. 1% Max. The use of air entrainment, air generators, or foaming agents may be needed to meet the performance specifications. The 28 day compressive strength testing and sampling will follow the procedure set forth in Test Method Numbers Nev. T 428 and ASTM C39, except cylinders shall not be rodded during sampling. The air content will be determined by Test Method No. Nev. T431 or T432 . Subsidence will be tested according to ASTM C940, except a standard 152 mm by 305 mm (6 in. by 12 in.) cylinder may be used for measurement purposes. Subsidence is defined as settlement or bleeding and shall not exceed 1%. Mixtures that require placement by use of a concrete or grout pump will be allowed a maximum subsidence of 2%. Slump tests may be performed on a random basis using Test Method No. Nev. T438 for the purpose of controlling consistency at the job site. 207 BACKFILL 102 CONSTRUCTION
207.03.01 General. Compact with mechanical tamping units.
Compact foundations for culvert pipe to not less than 90% of the maximum density and for reinforced concrete boxes to not less than 95% of the maximum density as determined by Test Method No. Nev. T10 8. The in -place density will be determined by Test Metho d No. Nev. T102 or T103. Place backfill material in uniform horizontal layers not exceeding 200 mm (8 in.) in loose thickness before compaction. Bring up uniformly on all sides of the structure or improvement. Moisten each layer of backfill as necessary a nd compact thoroughly until 90% of the maximum density is achieved. Compact each layer of backfill placed for abutments, piers, retaining walls, and wingwalls for bridges until 95% of the maximum density is achieved as determined by Test Method No. Nev. T1 08. The in-place density will be determined by Test Method No. Nev. T102 or T103. Do not compact backfill material by ponding or jetting. Deposit material resulting from structure excavation, not used as backfill, in roadway embankments according to Sect ion 203 or otherwise dispose of along the roadway in an approved manner. Do not place backfill material until the structure or facilities have been inspected and approved for backfilling. Do not deposit backfill material against the back of concrete abutm ents, concrete retaining walls or the outside walls of concrete box culverts until the concrete has reached an age of 14 days or the concrete has developed a compressive strength of 17 MPa (2,500 psi) as determined by ASTM C39. Where backfill is placed ag ainst waterproofed surfaces, take care not to damage the waterproofing material.
207.03.02 Placing and Compacting at Abutments, Piers, and Walls. Where backfill is to be placed on one
side of an abutment, wingwall, pier, retaining wall, or headwall, exerc ise care during placement and compaction of backfill material to prevent over compacting to the point of displacing line or batter or both. Step-cut or bench existing slopes which are shaped so as to cause a wedge action in the backfill, before backfillin g.
207.03.03 Placing and Compacting at Culverts. Place backfill along both sides of the culvert equally in
uniform layers not exceeding 200 mm (8 in.) in loose thickness before compaction. Take care in placing and compacting the material under the haunch es of pipe. Continue backfilling as described to the level of the ground or to an elevation 150 mm (6 in.) above the structure in the case of a pipe culvert in projection, or even with the top of the structure in the case of a RCB culvert in projection. Do not allow construction equipment or other traffic to cross any culvert until a safe minimum depth of fill above the culvert has been placed and compacted. Protect the structure from superimposed loading created by construction equipment. Repair any dama ge done to the structure or replace the structure without extra compensation. Take care in backfilling arches. Cover arches in layers conforming to the shape of the arch and tamp thoroughly.
207.03.04 Slurry Cement Backfill Placement. Manufacture slurry cement backfill at plants that qualify as
approved sources for re ady-mix concrete suppliers and deliver to the site in transit -mix trucks. After delivery and immediately before discharge, agitate the mix at mixing speed for a minimum of 70 revolutions. Discharge or pump the mix from the transit -mix truck into the space to be backfilled. When backfilling pipe culverts, distribute the mix evenly to prevent movement of the pipe. Placement may be required in stages to prevent uplifting of the pipe. Take a ppropriate measures such as installing straps or soil anchors to secure pipes from movement during fill placement. BACKFILL 207 103 Do not place slurry cement backfill on frozen ground. Protect slurry cement backfill from rapid surface moisture loss and from freezing for 3 6 hours after placement. Do not allow vehicle traffic or placing of pavement surfaces thereon until a penetration resistance of 4.1 MPa (600 psi) has been achieved using a hand held penetrometer according to ASTM C403. This penetration will be considered achieved when a person weighing at least 68 kg (150 lb), by use of their body mass as an axial load, cannot penetrate the slurry cement backfill with the square cut end of a No. 13 (#4) steel rei nforcing bar. METHOD OF MEASUREMENT
207.04.01 Measurement. Backfill, granular backfill, and slurry cement backfill will be measured by the cubic
meter (cubic yard). The estimated quantities shown on the plans, plus or minus authorized quantity changes, w ill be the quantity used for payment. The Engineer or the Contractor may, however, request recalculation of quantities. Submit request for recalculation of quantities in writing. When quantities are recalculated, the recalculated quantities will be used f or payment. BASIS OF PAYMENT
207.05.01 Payment. The accepted quantities, measured as provided above, will be paid for at the contract
price per unit of measurement for the pay items listed below that are shown in the proposal. Payment will be full compen sation for the work prescribed in this Section. The limits of backfill, granular backfill or slurry cement backfill shown in the plans shall be used for the method of measurement and payment only. There will be no additional compensation for any additiona l backfill materials required for excavations required to meet the OSHA regulations or for the elimination of shoring. When material from structure excavation is unacceptable as backfill and backfill material is obtained from roadway excavation, borrow or from base materials, it will be paid for both as backfill and the respective bid item from which it is obtained. When granular backfill is called for, it will be paid as granular backfill only. When an item for backfill does not appear in the proposal, backfill will be considered as incidental to the installation of the structure and compensation shall be considered as being included in the contract prices for other items of the work. Payment will be made under: Pay Item Pay Unit Backfill ................................ ................................ ................................ ................................ .............................. Cubic Mete r (Cubic Yard) Granular Backfill ................................ ................................ ................................ ................................ ................ Cubic Meter (Cubic Yard) Slurry Cement Backfill ................................ ................................ ................................ ................................ ....... Cubic Meter (Cubic Yard) 105 SECTION 209 DRAIN BACKFILL DESCRIPTION
209.01.01 General. This work consists of furnishing, hauling, placing, and compacting drain backfill material
around structures or perforated underdrains. MATERIALS
209.02.01 General. Material shall conform to the following Subsection:
Drain Backfill ................................ ................................ ................................ ................................ ........................... Subsection 704.03.01 CONSTRUCTION
209.03.01 General. Compact drain backfill to the satisfaction of the Engineer.
Do not compact by ponding or jetting.
209.03.02 Underdrains. Excavate and place drain backfill according to Section 607.
METHOD OF MEASUREMENT
209.04.01 Measurement. Drain backfill will be measured by the cubic meter (cubic yard).
BASIS OF PAYMENT
209.05.01 Payment. The accepted quantities, measured as provided above, will be paid for at the contract
price per unit of measurement for the pay item listed below that is shown in the proposal. Payment will be full compensation for the work prescribed in this Section. Payment will be made under: Pay Item Pay Unit (type) Drain Backfill ................................ ................................ ................................ ................................ ........... Cubic Met er (Cubic Yard)