State of California	 Business, Transportation and Housing Agency 

DEPARTMENT OF TRANSPORTATION 

Memorandum Flex your power! 

Be energy efficient! 

To:	 DEPUTY DISTRICT DIRECTORS, Construction Date: June 7, 2012 

DEPUTY DIVISION CHIEF, Structure Construction 

CONSTRUCTION MANAGERS File: Division of Construction 

SENIOR CONTRUCTION ENGINEERS CPD 12-2 

RESIDENT ENGINEERS 

From: MARK LEJA 

Chief 

Division of Construction 

Subject:	 Contractor Option for Use of Warm Mix Asphalt Technologies in Hot Mix Asphalt 

This directive provides guidance for implementing a contractor-requested option to use an approved 

Warm Mix Asphalt (WMA) technology during Hot Mix Asphalt (HMA) production for ongoing projects 

that contain HMA Type A, Type B, or RHMA-G specifications. Caltrans has developed a new standard 

special provision, Warm Mix Asphalt Technology Option, to encourage the use of warm mix asphalt by 

contractors. The Caltrans approved WMA technologies are available at the website: 

http://www.dot.ca.gov/hq/esc/approved_products_list/ 

WMA is defined as HMA produced at temperatures no greater than 275°F. When WMA technologies are 

used to aid mixing and compaction of HMA produced at temperatures greater than 275 °F, it is defined as 

HMA with WMA technology. The contractor-option specification allows a contractor to use either WMA 

technology to produce HMA at lower temperatures which reduces HMA plant fuel consumption and 

plant emissions during HMA production, or HMA with WMA technologies to aid in HMA mixing in the 

plant and HMA compaction in the field. 

Some contracts currently require a contractor to produce HMA with approved WMA additive technology. 

This directive does not apply to projects where the required use of a warm mix technology is included in 

the contract special provisions. A contractor’s request to substitute WMA foaming technology for a 

WMA additive technology on contracts using HMA with required use of WMA technology must not be 

authorized by the resident engineer. 

Procedure for Implementing New Specification on Ongoing Projects 

If the contractor requests to use WMA technology for HMA Type A, Type B, or RHMA-G, issue a 

change order to allow the use of WMA following the requirements of the new specification (see 

attached). 

•	 For ongoing projects that do not have an approved Job Mix Formula (JMF), the contractor must 

meet all of the requirements in the WMA specification. 

•	 For ongoing projects that have an approved JMF the following applies: 

o	 Contractor must submit a new JMF with the submittals as detailed in the specification. 

o	 For WMA water injection foam technology, the contractor is not required to do a new mix 

design using the WMA foaming technology. 

o	 For WMA additive technology, in lieu of performing a new mix design, the contractor may 

produce quality characteristics test results for the submitted JMF, as specified in Section 

39-1.03B of the Standard Specifications, except that the tests are performed at the mix design 

“Caltrans improves mobility across California” 
 

 

DEPUTY DISTRICT DIRECTORS, Construction, et al. 

June 7, 2012 

Page 2 

Optimum Bitumen Content as shown on form CEM-3512, “Contractor Hot Mix Asphalt 

Design Data.” 

o	 JMF verification is required prior to use of WMA on the project. 

o	 A production start-up evaluation is not required when a new JMF with WMA is used on the 

project. For Standard and QC/QA construction process projects with compaction 

requirements, verify compaction on the first day of production of WMA on the project to 

ensure that the contractor is meeting compaction requirements with the chosen WMA 

technology. 

For quality control during production, ensure the contractor performs the following additional required 

tests: 

•	 AASHTO T 324 (Modified) Hamburg wheel track test. Ensure the contractor submits the test 

results and tested sample set within 7 days of sampling. 

•	 California Test 371 tests for dry strength and tensile strength ration are required at a frequency 

of every 10,000 tons of HMA production. 

For HMA with WMA technology placed under the method construction process or when method 

compaction is required for HMA placed under the Standard or QC/QA construction process, WMA 

production, transporting, spreading, and compacting temperatures must comply with the requirements of 

Section 39, “Hot Mix Asphalt,” of the Standard Specifications. 

For HMA with WMA technology placed under the Standard or QC/QA construction process, WMA must 

be produced at a temperature between 240°F and 325°F. For WMA placed under the Standard or QC/QA 

process when method compaction is not required, the contractor determines transporting, spreading, and 

compacting temperatures. 

There should be no cost or credit to the state for implementing the contractor-initiated change order. No 

extension of contract time should be included in the change order. A sample change order memorandum, 

sample change order, change order attachment—WMA specification, and a Federal Highway 

Administration blanket prior approval for using warm mix asphalt technology are attached. This directive 

serves as delegation of authority from the Division of Construction and the Federal Highway 

Administration for change orders, when implemented under its requirements. 

If you have questions about warm mix asphalt, please contact Kee Foo, Division of Maintenance, at 

(916) 274-6077 or kee_foo@dot.ca.gov, or Chuck Suszko, Division of Construction, at (916) 227-7314 

or chuck_suszko@dot.ca.gov. 

Attachments: 1. Contractor Option for Use of WMA Technologies in HMA—Sample Contract 

Change Order Memorandum 

2. Contractor Option for Use of WMA Technologies in HMA—Sample Contract 

Change Order 

3. Contractor Option for Use of WMA Technologies in HMA—Change Order 

Specification Attachment 

4. FHWA Form CA-358 (c), “Record of Blanket Prior Approval for Major Contract 

Change Order” 

“Caltrans improves mobility across California”