SECTION 516: FLOWABLE FILL
516.1 Description
This Work consists of providi ng and placing flowable fill.
516.2 Materials
516.2.1 General
Flowable fill is a flowable mixture of Portland cement, fly ash , aggregates, admixtures and water.
516.2.2 Mix Design
The State Materials Bureau is responsible for approving the mix design for flowable fill. Approval of a flowable fill mix design by the State Materials B ureau will be valid for a period of five (5) years unless revoked due to performance problems.
516.2.3 Cement
See Section 509, “Portland Cement Concrete Mix Designs.”
516.2.4 Aggregate
The Contractor shall provide a uniform mixture of fine aggregat e or coarse and fine aggregate. The Contractor shall provide coarse and fine aggreg ate with a gradation in accordance with Table 516.2.4:1, “Aggregate Mixture Gradation R equirements.” Table 516.2.4:1 Aggregate Mixture Gradation Requirements Sieve size % passing One (1) inch 100 3/8 inch 95 – 100 No. 4 80 – 100 No. 8 60 – 95 No. 16 45 – 80 No. 30 25 – 60 No. 50 5 – 45 No. 100 5 – 35 No. 200 0 – 30
516.2.5 Water
The Contractor shall provide concrete mix water in accordance w ith Section 509, “Portland Cement Concre te Mix Designs.”
516.2.6 Air-Entraining Admixture
The Contractor may use an air-entraining admixture to provide a ir entrainment no greater than 35% in the flowable fill. The Contractor shall provide approved Class F, Class C, or Clas s C/F blended fly ash in accordance with Section 509, “Port land Cement Concrete Mix Desi gns.”
516.2.8 Water-Reducing Admixture
The Contractor may use a water-reducing admixture.
516.2.9 Proportioning and Physical Property Requirements in the Laboratory
The Contractor shall provide a flowable fill mix design in acco rdance with the following limits: 1. Cement, maximum 50 lbs/yd³. 2. Fly Ash, from 150 lbs/yd³ to 300 lbs/yd³. 3. Air Content, optional. 4. Slump, from eight (8) inch to 11 inch. 5. Water/cement ratio, proportioned by weight to produce a slum p within the prescribed limits. 6. Consistent aggregate throughout the concrete mixture. 7. Compressive strength will not exceed 150 psi at 28 Days. 8. Cast the test specimens in f our (4) inch × eight (8) inch te st cylinders, perforated on the bottom with four (4) 1/4 inch diameter holes for free drain ing. 9. Keep the test cylinders in a moist environment, but do not c ure in a curing tank. 10. Cast six (6) compressive strength test cylinders in the Lab oratory. Test two (2) cylinders at seven (7) Days, two (2) at 28 Days, and two (2) at 56 Days.
516.3 Construction Requirements
516.3.1 Batching, Mixing, and Transporting
The Contractor shall perform batching, mixing, and transporting in accordance with Section 510, “Portland Cement Concrete.”
516.3.2 Testing Flowable Fill in the Field
The Contractor shall obtain the State Materials Bureau’s appro val of the flowable fill mix properties before using the mix in the field. For field testing, the Contractor shall use a standard (15 lb) T-post fence driver to drive a #6 reinforcing bar with a flat end into the flowable fill Mater ial 24 h after placement. The Contractor shall lift the driver until the bottom of the driver is even with a mark located six
6.inches below the top of the rebar, and then allow it to fal l under its own weight. The Contractor shall remove and replace the flowable fill if fewer than six (6) blows or more than 25 blows are required to drive the rebar 12 inches into the fil l. The Contractor shall not use compressive strength test cylinder s for field-testing purposes.
516.3.3 Pre-Placement Requirements
Before placing flowable fill, the Contractor shall remove any loose or uncompacted soils from the area to be filled. The Contractor shall ensure that a ll areas in which soils or Section 516 Flowable Fill Page 390 construction Materials have sl oughed off or collected are compl etely cleared. The Contractor shall not place flowable fill against loose or uncompacted surf aces/materials. The Contractor shall ensure that all pipes or other embedded i tems which would otherwise float to the top of the flowable fill are adequately secured to prevent their floating out of position.
516.3.4 Placing
The Contractor shall place flowable fill uniformly to prevent v oids in or segregation of the bedding and filling Material. The Contractor shall secure the C ulvert or pipe from movement. The Contractor shall place the flowable fill by direct discharg e from a ready mix truck, pumping, or other method approved by the Project Manager. The Contractor shall place the flowable fill in layers no more than 12 ft high. The Contracto r shall place the flowable fill in layers no more than four (4) ft high for areas that require for ming. The Contractor shall not place the individual layers until flowable fill in a previously placed layer has been in place at least two (2) h. The Contractor shall submit a written request and obtain writte n approval from the Assistant District Engineer – Con struction before placing the f lowable fill in a full depth layer. The Contractor shall not place the flowable fill on frozen grou nd or while it is raining. The Contractor shall protect flowabl e fill from flooding for at lea st 24 h after placement. If necessary, the Contractor may place flowable fill in standin g water that is positioned to keep the outside water from contaminating or mixing with the fl owable fill. The Contractor shall not allow any embedded items to float or o therwise dislodge. The Contractor shall secure pi pe to compensate for buoyancy. The Contractor shall fill the areas between the walls of the ex isting CBC and an inserted CMP thoroughly. The Contractor shall not disturb the flowable fill Material for at least 24 h after placement. The Contractor may reduce this 24-hour period, if the penetrati on resistance of the Material justifies, as tested in accordance with Section 516.3.2, “Testi ng Flowable Fill in the Field.”
516.3.5 Application of Load
The Contractor may cover the flo wable fill within 24 h after pl acement, if a person weighing at least 150 lb does not sink into the Material more t han one (1) inch, if standing on a four (4) inch × four (4) inch wooden block.
516.3.6 Temperature and Weather Limitations
The Contractor shall not place flowable fill when the air tempe rature is lower than 35 °F. The Contractor may begin placement only when weather conditions are favorable and the air temperature is a least 35 °F and rising. If the air temperatur e at the time of placement is less than 40 °F, the Contractor shall place flowable fill that has a temperature of at least 50 °F.
516.4 Method of Measurement
The Department will measure flowable fill using the dimensions shown in the Contract or as approved by the Project Manager. The Department will consid er flowable fill used at the Section 516 Flowable Fill Page 391 Contractor's option to be Incidental to the associated Bid Item .
516.5 Basis of Payment
PAY ITEM PAY UNIT Flowable Fill Cubic Yard
516.5.1 Work Included In Payment
The following Work will be consi dered as included in the paymen t for the main item and will not be measured or paid for separately: 1. When called for in the Contract, or the Contractor proposes its use and is approved by the Project Manager, flowable fill can be used for backfill in Culvert installations; and 2. No measurement or payment will be made for Work and Material s associated with backfilling pipes with flowable fill. This will be included in the Contract unit price per linear foot of Culvert pipe. Section 517: Precast Concrete Structures Page 392
Source: New Mexico Standard Specifications for Highway and Bridge Construction, 2019 Edition. Pages 0–0 of 974.