SECTION 424: WARM MIX ASPHALT (WMA) (MAJOR PAVING)
424.1 Description
This Work consists of construc ting one (1) or more pavement co urses of Warm Mix Asphalt (WMA) on a prepared base milled surface. WMA shall be produced in a mixing plant and stored, hauled, pl aced and compacted in accordance with the requirement s of this Section and as shown i n the Contract. Section 423, “Hot Mix Asphalt – Superpave (Major Paving)” shal l be complied with except as modified herein.
424.1.1 Definition
Warm Mix Asphalt (WMA) is a g eneric term used to describe the reduction in production paving and compaction temperatures achieved through the use of one (1) of the approved WMA Technologies. Some modification to WMA plants may be necessary to accommodat e the WMA Technologies as noted in Section 424.3, “Construction Requireme nts.”
424.2 Materials
424.2.1 General
WMA may be produced by one (1) or a combination of several tec hnologies which may include WMA plant foaming processes and Equipment, mineral addi tives or chemicals that allow the reduction of the production temperatures. WMA is a mixture of asphalt binder, Warm Mix Additive (or tech nologies), aggregate, blending sand, mineral filler, and mineral admixture Material. The warm mix additive, or technology, shall be approved by the Department and included in the most current Approved Products List (APL). Unless otherwise prohibited in the Contra ct, the Department will allow Recycled Asphalt Pavement (RAP) in WMA mixes as long as the res ulting mixture conforms to all Specification requirements. A technical representative of W arm Mix Additive Supplier, incl uding contact information shall be designated in writing vi a the mix design submittal pro cess. The representative is expected to ensure that the Warm Mix Additive is handled proper ly. The representative does not have the authority to allow any deviation from the Departme nt Specifications and Project requirements.
424.2.2 Aggregate
Refer to Section 423.2.2, “Aggregate.” Note: HMA will be replaced with WMA.
424.2.3 Asphalt Binder
Refer to Section 423.2.3, “Asphalt Binder.”
424.2.3 1 Warm Mix Additive or Technology
Section 424: Warm Mix Asphalt (WMA) (Major Paving) Page 231 Only Warm Mix Additives or Technologies approved by the Produc t Evaluation Program and listed on the NMDOT Approved Products List (APL) can be use d on Department Projects. To be placed on the APL, the WMA additive Supplier shall verif y that the binder with the additive meets the PG grade of the specified binder. The poten tial additive Supplier shall demonstrate this to the Department by evaluating the Asphalt Bi nder containing the WMA additive at the expected additive dosage rates for compliance w ith the specified PG grade in accordance with AASHTO M320, Table 1 and Section 402.2.2.1.1, “ Performance Graded Asphalt Binder.” The type and dosage rate of Warm Mix Additives shall comply wi th the recommendations of the Warm Mix Additive Supplie r. Warm Mix Additive dosage ra tes shall not deviate from those recommended by the Warm Mix Additive Supplier. If a term inal blend Warm Mix Additive is used, the dosage rate shall be shown on the Materia ls Certificate of Compliance. After the Warm Mix Additive is introduced, the PG grade of the binder shall comply with the PG grade as specified in the Contract. For foamed asphalt systems, only foam systems that approved by the State Asphalt Engineer shall be used. Foamed as phalt systems, are not part o f the NMDOT APL.
424.2.4 Mineral Admixtures
Refer to Section 423.2.4, “Mineral Admixture.”
424.2.5 Blending Sand
Refer to Section 423.2.5, “Blending Sand.”
424.2.6 Mineral Filler
Refer to Section 423.6, “Mineral Filler.” Note: HMA will be replaced with WMA.
424.2.7 Reclaimed Asphalt Pavement
Refer to Section 423.2.7, “Re claimed Asphalt Pavement.” Note: HMA will be replaced with WMA.
424.2.8 Mix Design
Refer to Section 423.2.8, “Mix Design.” Note: HMA will be replaced with WMA. In addition to the above reference, the Contactor shall provid e documentation confirming the WMA additive or technolog y blended with the asphalt binder results in asphalt cement that meets the specified PG Grade Asphalt Binder. The WMA Additive or Technolog y Supplier and the Asphalt Binder Supplier will recommend mixing, compaction, and maximum allowable temperature s to be used for the development of the mix design.
424.2.9 Job Mix Formula
Refer to Section 423.2.9, “Job Mix Formula.”
424.3 Construction Requirements
424.3.1 General
Refer to Section 423.3.1, “General.” Note: HMA will be replaced with WMA.
424.3.2 Mix Temperature Requirements
The Contractor shall not allow the temperature of the WMA to b e less than 215 degrees F or greater than 275 degrees F behind the laydown machine. WMA delivered to the Project with mix temperatures outside the Acceptable range shall, at th e sole discretion of the Project Manager, be removed and replaced at no cost to the Department.
424.3.3 Addition of Mineral Admixtures
Refer to Section 423.3.3, “Addi tion of Mineral Admixture.”
424.3.4 Equipment
Refer to Section 423.3.4, “Equipment.” Note: HMA will be replaced with WMA. The Contractor shall use Equipment and WMA technologies capabl e of producing an asphalt mixture that meets Specif ication requirements and is wo rkable at the minimum placement and compaction temperatures desired, regardless of st orage or haul distance considerations.
424.3.4 1 Mixing Plants
The Contractor shall modify t he asphalt mixing plant as requir ed by the manufacturer to introduce the WMA technology.
424.3.4 1.1 Plant Scales
Refer to Section 423.3.4.1.1, “Plant Scales.” In addition to the above reference, the Contractor shall modif y the asphalt mixing plant as required by the manufacture to introduce the WMA additive or te chnology.
424.3.5 Placement Operations
Refer to Section 423.3.5, “Placement Operations” except the fo llowing subsections as modified herein. Note: HMA will be replaced with WMA.
424.3.5 1 Weather Limitations
The Contractor shall not place WMA on wet or frozen surfaces o r if weather conditions prevent proper handling, finishing, and compacting. The Contra ctor shall place WMA when the Chill Factor is at least 35 °F and rising. If the air temp erature is 55 °F or warmer, the Contractor shall not cons ider the Chill Factor.
424.3.6 Sampling and Testing
Refer to Section 423.3.6, “Sampling and Testing.” Note: HMA will be replaced with WMA. In addition to the above referenc ed section the following shal l be complied: If the WMA additive Supplier indicates that the additive makes mix properties time defendant; the Plan must include how all of the required testin g will be completed in the designated time frame. This Plan will include how the Contract or will comply with the required testing within the Supplier’s specified time frames. It will a lso include how the Department will be supported, if necessary, to complete their tests within the time frame required if the testing cannot be performed at Department established facilities. This Plan must be reviewed and approved by the Project Manager and by the District Laboratory Supervisor prior to the placed of any WMA on the Project. If the Job Mix Formula changes, it shall be addressed in conformance with Section 423.2.9. 1, “Job Mix Formula Adjustment s.”
424.3.7 Dispute Resolution
Refer to Section 423.3.7, “Dispute Resolution.” Note: HMA will be replaced with WMA.
424.4 Method of Measurement
If the Department measures WMA by the square yard, the Departm ent will use the average width of the WMA in place and the length from station t o station along the centerline of the Roadway when calculating quantities.
424.5 Basis of Payment
Pay Item Pay Unit WMA Complete Ton or Square Yard WMA Ton or Square Yard The Department will pay for Accepted quantities at the Bid Ite m Unit Price, adjusted in accordance with Section 424.5.1, “Price Adjustments.” Providin g and transporting all cores, samples and storage containers shall be Incidental to the Pay I tems above.
424.5.1 Price Adjustments
Refer to Section 423.5.1, “Price Adjustments.” Note: HMA will be replaced with WMA.
424.5 2 Work Included in Payment
Refer to Section 423.5.2, “Work Included in Payment.” Section 450: Portland Cement Concrete Pavement (PCCP) (QLA) Page 235