Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

Long-Term Pavement Performance 

Warm-Mix Asphalt Study Final Report, 

Volume V: SPS-10 Performance 

Monitoring Guide

PUBLICATION NO. FHWA-HRT-22-022 FEBRUARY 2023 
FOREWORD

Warm-mix asphalt (WMA), an innovative material that is part of the Federal Highway 

Administration Every Day Counts program, has been implemented by State highway agencies 

throughout the United States. WMA covers a variety of categories, each designed to allow for 

the production and compaction of asphalt concrete at temperatures lower than conventional 

hot-mix asphalt (HMA).

Recognizing that a knowledge gap exists in the comparison of WMA and HMA over the 

performance life of each type of pavement, the Long-Term Pavement Performance (LTPP) 

program initiated this research to design a national experiment to study the performance of 

WMA relative to HMA. New test sections will be recruited into the LTPP program under the 

designation of the specific pavement studies (SPS)-10 experiment called “Warm Mix Asphalt 

Overlay of Asphalt Pavement Study.” 

The purpose of this volume of the report series is to document the guidelines for the development 

and implementation of the performance monitoring for the SPS-10 experiment for the LTPP 

program. This experiment is designed to capture information on the short- and long-term 

performance of WMA relative to HMA. This experiment has been structured to ensure 

consistency and compatibility with the existing LTPP program objectives and database while 

addressing information gaps regarding WMA performance. The intent of the SPS-10 experiment 

is to capture not only field performance but also laboratory test data that will provide both useragencies and researchers a better understanding of the potential benefits of WMA. Collectively, 

this information could be used for performance prediction.

Mark Swanlund 

Acting Director, Office of Infrastructure

Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 

(USDOT) in the interest of information exchange. The U.S. Government assumes no liability for 

the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers’ names appear in this report only because they are considered essential to the 

objective of the document. 

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve 

Government, industry, and the public in a manner that promotes public understanding. Standards 

and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality issues and adjusts its programs and processes to 

ensure continuous quality improvement. 
TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.

FHWA-HRT-22-022

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Long-Term Pavement Performance Warm-Mix Asphalt 

Study Final Report, Volume V: SPS-10 Performance 

Monitoring Guide

5. Report Date

February 2023

6. Performing Organization Code:

7. Author(s)

J. Puccinelli, P. Schmalzer, K. Senn (ORCID: 0000-0002-

9645-5370), L. McDonald

8. Performing Organization Report No.

9. Performing Organization Name and Address

NCE

1885 S Arlington Avenue, Suite 111

Reno, NV 89509

10. Work Unit No.

11. Contract or Grant No.

DTFH61-12-C-00017

12. Sponsoring Agency Name and Address

Office of Infrastructure Research and Development

Federal Highway Administration

6300 Georgetown Pike

McLean, VA 22101-2296

13. Type of Report and Period Covered

Final Report; September 2012–December 2014

14. Sponsoring Agency Code

HRDI-30

15. Supplementary Notes

Jack Springer (HRDI-30) served as the Contracting Officer’s Representative.

16. Abstract

This report presents guidelines for developing and implementing the performance monitoring program for 

Specific Pavement Studies-10 Warm-Mix Asphalt Study experiment test sections. Federal Highway 

Administration Long-Term Pavement Performance regional support contractors must follow these guidelines to 

develop performance monitoring plans tailored to the conditions encountered on each project.

17. Key Words

Asphalt concrete, LTPP, material properties, 

pavement, Specific Pavement Studies, warm-mix 

asphalt, performance monitoring, construction, 

SPS-10, hot-mix asphalt

18. Distribution Statement

No restrictions. This document is available to the public 

through the National Technical Information Service, 

Springfield, VA 22161.

https://www.ntis.gov

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

13

22. Price

N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized.
ii
iii

LONG-TERM PAVEMENT PERFORMANCE WARM-MIX ASPHALT STUDY 

PROJECT REPORT SERIES

This volume is the fifth of six volumes in this research report series. Volume I is the final report, 

and volume II through volume VI contain detailed information about the design and operations 

of the experiment. The following list contains the volumes of this series:

Volume Title Report Number

I Long-Term Pavement Performance Warm-Mix Asphalt 

Study, Volume I: Final Report

FHWA-HRT-22-018 

II Long-Term Pavement Performance Warm-Mix Asphalt 

Study Final Report, Volume II: SPS-10 Experimental 

Matrix and Research Plan

FHWA-HRT-22-019 

III Long-Term Pavement Performance Warm-Mix Asphalt 

Study Final Report, Volume III: SPS-10 Nomination 

Guidelines 

FHWA-HRT-22-020 

IV Long-Term Pavement Performance Warm-Mix Asphalt 

Study Final Report, Volume IV: SPS-10 Materials 

Sampling and Testing Requirements 

FHWA-HRT-22-021 

V Long-Term Pavement Performance Warm-Mix Asphalt 

Study Final Report, Volume V: SPS-10 Performance 

Monitoring Guide 

FHWA-HRT-22-022 

VI Long-Term Pavement Performance Warm-Mix Asphalt 

Study Final Report, Volume VI: SPS-10 Construction 

Documentation Guide 

FHWA-HRT-22-023 
iv

TABLE OF CONTENTS

CHAPTER 1. PERFORMANCE MONITORING OF SPS-10 TEST SECTIONS ................ 1

Objective .................................................................................................................................. 3

Pre-Overlay Monitoring ......................................................................................................... 3

Short-Term Performance Monitoring .................................................................................. 4

Long-Term Performance Monitoring ................................................................................... 4

REFERENCES .............................................................................................................................. 7
v 

LIST OF FIGURES

Figure 1. Diagram. Typical SPS-10 site layout. ............................................................................. 2

LIST OF TABLES

Table 1. Summary of short-term LTPP performance monitoring intervals. ................................... 4

Table 2. Summary of LTPP performance monitoring intervals. .................................................... 5

LIST OF ABBREVIATIONS

AC asphalt concrete 

FHWA Federal Highway Administration

FWD falling weight deflectometer

HMA hot-mix asphalt

LTPP Long-Term Pavement Performance

RSC regional support contractor 

SPS Specific Pavement Studies

WMA warm-mix asphalt 

1 

CHAPTER 1. PERFORMANCE MONITORING OF SPS-10 TEST SECTIONS

This report provides guidelines for the development and implementation of the performance 

monitoring program for the Federal Highway Administration’s (FHWA’s) Long-Term Pavement 

Performance (LTPP) Specific Pavement Studies (SPS)-10 experiment test sections. FHWALTPP regional support contractors (RSCs) must follow these guidelines when developing 

performance monitoring plans tailored to the conditions encountered on each project. 

The SPS-10 experiment is designed to capture information on the performance of warm-mix 

asphalt (WMA) compared to hot-mix asphalt (HMA), in both the short and long term. The 

experiment was designed to compare the performance of WMA to HMA. Field performance will 

be captured over the long term, and data from laboratory testing of WMA materials will be 

provided to researchers looking to evaluate various features of WMA. Collectively, this 

information can be used to understand the potential benefits of WMA and generate more 

accurate performance predictions.

The SPS-10 experiment described in this report is intended for test sections not previously 

included in the LTPP program. Projects nominated for the SPS-10 experiment will be 

constructed specifically to satisfy cells within the experimental matrix. They will adhere to the 

guidelines developed by the project team and approved by FHWA. Because these sections will 

be nominated for the program before rehabilitation, all construction activities, material 

properties, and sampling will be documented to ensure a complete dataset. Each SPS experiment 

in the LTPP program is designed to have limited goals, construction needs, and experimental 

approaches. The experiments are generally designed to be intensive studies of a few independent 

variables. This document defines the goals and objectives of the SPS-10 experiment and the 

independent variables to be studied. 

The SPS-10 experiment requires the construction of a minimum of three test sections at each 

project site. Figure 1 demonstrates a sample test section layout, including stationing, transition 

areas, and pavement layers. Construction will be limited to overlays of asphalt concrete (AC) 

pavements only. The minimum three test sections are as follows: 

• Highway agencies’ standard mix (control section). 

• Mix with WMA foaming process category. 

• Mix with WMA chemical additive category. 
2 

Source: FHWA. 

Figure 1. Diagram. Typical SPS-10 site layout. 
3 

WMA technologies currently available can be grouped into the following four categories (some 

technologies are a combination of these):

• Foaming additive. 

• Chemical additive. 

• Organic additive. 

• Foaming process.

The LTPP SPS-10 experiment focuses on the chemical additive and foaming process categories. 

To compare the materials in the study, the pavement structure and thicknesses of the layers 

containing the experimental mixtures must be the same on all test sections. Agencies are 

encouraged to take the opportunity afforded by the construction of these experimental test 

sections—whose performance will be uniformly monitored over the long term—to construct 

supplemental sections investigating experimental factors of specific agency interest.

OBJECTIVE

The objectives of the SPS-10 experiment are to: 

• Evaluate and improve the practical aspects of implementing a WMA system through a 

hands-on field trial by interested highway agencies. 

• Compare the performance of the selected WMA technologies against mixes designed 

using current highway agencies’ HMA specifications, asphalt-aggregate specifications, 

and mix design procedures. 

• Provide long-term performance data for evaluation and refinement of the WMA 

technologies, design procedures, and models. 

• Test the sensitivity of a WMA technology relative to low-temperature cracking, fatigue, 

or permanent deformation distress factors.

• Provide highway agencies the opportunity to evaluate the performance of other 

experimental features by constructing supplemental sections.

A key component to achieving the objectives of the SPS-10 experiment is to develop and execute 

a performance monitoring plan capable of tracking and collecting the long-term WMA data. The 

guidelines for the periodic collection of monitoring data are described within this report.

PRE-OVERLAY MONITORING

Because the SPS-10 experiment is based on the overlay of existing AC pavements, it is crucial to 

capture the condition of the existing pavement before the overlay. As such, the performance 

monitoring plan will include pre- and post-overlay testing. Current LTPP practice is to capture 

the condition within 6 mo before and 6 mo after completion of the overlay. This timing may need 

to be shifted to account for late-season paving, where the 4-mo window would be in the middle 

of winter in cold-weather locations. For the SPS-10 experiment, pre-overlay testing will consist 
4 

of manual distress surveys, falling weight deflectometer (FWD) testing, transverse profile, 

longitudinal profile, and texture measurements. Manual distress surveys are performed using the 

Distress Identification Manual for the Long-Term Pavement Performance Program (Miller and 

Bellinger 2014). Likewise, the LTPP Manual for Collecting and Processing Longitudinal 

Profile, Macrotexture, and Transverse Profile Data is used without modification (Perera and 

Elkins [forthcoming]). The FWD testing plans (i.e., lane designations, drop sequences, 

stationing) for the SPS-1 in the LTPP Manual for Falling Weight Deflectometer Measurements, 

version 4.1, are used for SPS-10 WMA projects (Schmalzer 2006). 

SHORT-TERM PERFORMANCE MONITORING

The SPS-10 experiment will have a modified monitoring frequency to collect early-life 

performance. This increased frequency will capture early rutting concerns (if the WMA was

paved early in the summer) and moisture susceptibility issues (for late-season paving). The 

increased frequency monitoring includes distress, FWD, texture, transverse profile, and 

longitudinal profiles. The proposed data collection would occur at an interval of t = 0, 3–6, 12, 

and 18 mo. This interval will be commensurate with the coring intervals identified in the 

project’s materials sampling and testing plan (Puccinelli et al. 2022). For the time interval t = 0, 

the data collection will be done within 30 d of the finished construction. The next data collection 

will fall within 3–6 mo after construction. For the 12- and 18-mo intervals, the data collection 

will be done either 30 d before or 30 d after the interval. Table 1 summarizes the desired shortterm monitoring levels for the SPS-10 experiment. Complete details on time series coring can be 

found in volume IV of this report series.

Table 1. Summary of short-term LTPP performance monitoring intervals.

Time After 

Construction (mo)

Longitudinal 

Profile/Texture

Distress/Transverse 

Profile FWD

0    

3–6    

12    

18    

LONG-TERM PERFORMANCE MONITORING

Monitoring data are collected periodically throughout the life of each test section to monitor the 

structural and functional condition of the pavement section over time. These data provide a 

historical database for developing relationships between performance, traffic counts and axle 

loads, age, maintenance, and other significant variables. 

Directive GO-68 established the current performance monitoring guidelines (Nehme 2019). 

Table 2 summarizes the desired and minimum monitoring levels by experiment, including the 

SPS-10 experiment. 
5 

Table 2. Summary of LTPP performance monitoring intervals. 

Performance Measure Desired Level Maximum Allowable 

Interval Period

Longitudinal profile/texture Annual Every 2 yr 

Distress/transverse profile Annual Every 2 yr 

FWD Every 3 yr Every 5 yr 

After the first 18 mo of short-term monitoring, the monitoring frequency of the WMA 

experiments is the same as that of the other SPS-10 experiments listed in table 2. The SPS-1 test 

plan will adequately capture the necessary data for WMA experiments. This monitoring data 

should be obtained and reported for each test section. 

The performance monitoring plan set forth in this document will be used in all SPS-10 

experiments for LTPP unless otherwise noted in the most current LTPP directives. In the event 

of resource constraints, the RSCs will work with FHWA to establish a reduced monitoring plan. 

It is in the interest of the LTPP that the core sections receive priority for performance 

monitoring.

7 

REFERENCES

Miller, J., and W. Bellinger. 2014. Distress Identification Manual for the Long-Term Pavement 

Performance Program (Fifth Revised Edition). Report No. FHWA-HRT-13-092. 

Washington, DC: Federal Highway Administration. 

Nehme, J. 2019. LTPP Directive GO-68, Pavement Performance Monitoring Guidelines. 

Washington, DC: Federal Highway Administration. 

Perera, R., and G. Elkins. [forthcoming]. LTPP Manual for Collecting and Processing

Longitudinal Profile, Macrotexture, and Transverse Profile Data. Report No. 

FHWA-HRT-21-096. Washington, DC: Federal Highway Administration. 

Puccinelli, J., P. Schmalzer, K. Senn, and L. McDonald. 2022. Long-Term Pavement 

Performance Warm-Mix Asphalt Study Final Report, Volume IV: SPS-10 Materials 

Sampling and Testing Requirements. Report No. FHWA-HRT-22-021. Washington, DC: 

Federal Highway Administration.

Schmalzer, P. 2006. LTPP Manual for Falling Weight Deflectometer Measurements, Version 

4.1. Report No. FHWA-HRT-06-132. Washington, DC: Federal Highway 

Administration.

HRDI-30/02-23(WEB)E Recycled

Recyclable

Recommended citation: Federal Highway Administration, Long-Term Pavement Performance 

Warm-Mix Asphalt Study Final Report, Volume V: SPS-10 Performance Monitoring Guide

(Washington, DC: 2023) https://doi.org/10.21949/1521718