Use of Alternative Pozzolanic Materials Towards Reducing Cement Content in Concrete Pavements

Status: Active
MnDOT Contract Number: 1048190
Project End Date: April 30, 2026

Objectives

In pozzolanic substitution, replacement of cement in concrete translates to a significant reduction of carbon footprint. This substitution must be done without compromising the strength and durability of the concrete. If the simple use of higher percentages of limestone substitution do not compromise durability, it defines a sustainable practice. Moreover, if natural pozzolanic materials result in long term mechanical strength and durability, they too contribute toward increased sustainability.

Due to the renewed interest seen nowadays in using natural and recycled materials-based pozzolans as a replacement for Portland cement, this project seeks to investigate the sustainability and resiliency of such a practice within pavements. Although much research has gone into pozzolanic substitution, there is a lack in the knowledge base regarding the sustainable limits in the use or inclusion of limestone in cementitious blends. Additionally, there is a missing link between limestone content and actual influence of the porosity of limestone that may have influence on absorption and possible desorption within the matrix.

Member states are seeking increased confidence in the usage of ternary or quaternary blends. One aspect of this study will be to provide the limits for limestone inclusion, which will also serve as guidance to the industry and agencies. The other interest is understanding the feasibility of using alternative natural pozzolans and substandard fly-ash materials (i.e. reclaimed ash). Implementation would involve dissemination of the information in the form of a tech brief and final report posted on the NRRA Team webpage(s), as well as presentations at NRRA and other pavement related conferences.

Data will be collected on an estimated six to eight 250-foot-long pavement test sections and provided to the research team by MnROAD staff. This data will include (but not be limited to) results from routine FWD testing, seasonal ride quality measurements, distress surveys, load testing of embedded dynamic strain sensors, faultmeter and MIRA measurements, joint opening measurements (automated and manually collected), measurement of warping and curling, and extracted cores.

The goal of this research proposal is to investigate the factors impacting production and placement of concrete pavement utilizing alternative pozzolanic materials, as well as determine the field performance when exposed to heavy traffic loading and extreme climatic conditions.

The following topics should be addressed with this investigation:

Determine what characteristics need to be considered when selecting these materials.
What factors need to be considered when designing concrete mixtures containing these materials.
Develop guidelines for successfully producing and placing these types of concrete in the field.
Determine what testing needs to be performed during paving and acceptance after hardening.
Impact of alternative pozzolanic materials on structural pavement performance and durability.

Tasks

Task 1: Literature review

Due to extensive previous research on this topic, Contractor’s team has an extensive library of literature related to the use of Alternative Supplementary Cementitious Materials (ASCMs), including those planned for inclusion in State’s test sections. This task will compile those documents, search common databases (e.g., Transportation Research Board (TRB) Transportation Research International Documentation [TRID] Database, state Department of Transportation (DOT) publication sites, Google Scholar) for newly published studies and information, and extract relevant information. Each reference will be summarized, cited, and catalogued in a spreadsheet for easy access during report preparation. A technical memorandum will be prepared that summarizes the findings of the literature and identifies gaps in current knowledge. A summary presentation will be provided to the TAP and any comments will be integrated into the task deliverable.

Deliverable: A technical memorandum and presentation to the TAP, 2/28/2023
Date due: February 28, 2023

Task 2: Prepare materials

Contractor will visit the MnROAD project site to observe production, delivery, paving, and testing of one or more concrete mixtures made with ASCMs. Construction testing data will be collected by State and provided to the research team. The Anticipated Tests list, below, provides a list of anticipated testing data that will be produced for this task, although additional testing may be conducted (e.g., alkali-silica reactivity, restrained shrinkage, rapid chloride penetrability, etc.). These data will be entered into a Microsoft Access database and crosslinked with test section information (e.g., number, type of mix, date of paving). Data will be compiled, and descriptive statistics calculated for comparison with control section (typical State concrete mixture). The results of the petrographic analysis and air-void system analysis (by others) will be reviewed, and key findings compared to construction test data. A report will be prepared to summarize test results and task findings and will be submitted to the TAP for review. A summary presentation will be provided to the TAP and comments will be integrated into the task deliverable.

Anticipated Tests

Tests on Fresh Concrete

American Association of State and Highway Transportation Officials (AASHTO) T 119 (Slump)
AASHTO TP 129 (V-Kelly)
AASHTO T 121 (Unit Weight)
AASHTO T 152/TP 118 (Air Content / SAM Number)
AASHTO T 318 (Water Content)
AASHTO T 365 (Chemical Deicer Damage of Paste)

Tests on Hardened Concrete

AASHTO TP 119 with PP 84 (Resistivity/Formation Factor)
AASHTO T 97/T 22 (Flexural Strength)
AASHTO T 22 (Compressive Strength)
MnDOT Specification 2461.3G.6 (Maturity)
AASHTO T 160 (Unrestrained Volume Change)
AASHTO T 161 (Freeze-Thaw Durability)
American Society for Testing and Materials (ASTM) C457 (Air Voids in Hardened Concrete)
ASTM C856 (Petrographic Analysis)

Deliverable:Summary report and presentation to the TAP and progress update during
a NRRA monthly meeting.
Date due: June 30, 2023

Task 3: Constructability evaluation

Several factors impact the ability to produce consistent quality concrete paving mixtures in large volumes. Mixture variability, particular with regards to workability and set time, can result in poor consolidation and finishing, less durable concrete, and detrimentally impact pavement performance. Under this task, Contractor will evaluate construction records to assess the feasibility of large-scale construction of the concrete mixtures used at MnROAD. The following elements will be evaluated to assess the constructability of concrete mixtures made with ASCMs: material availability, material handling considerations, issues related to mixing, transporting, placing, and curing, impact of admixtures, and ease of making field adjustments. In addition to the information gathered as part of the literature review conducted under Task 1, the comprehensive report documenting the construction of the test cells at MnROAD (provided by State) is expected to provide key insights related to any issues encountered during construction. Contractor will prepare a report to summarize findings regarding feasibility of large-scale construction and submitted to the TAP for review. A summary presentation will be provided to the TAP and any comments will be integrated into the task deliverable.

Deliverable:Summary report and presentation to the TAP.
Date due: October 31, 2023

Task 4: 1st year performance update

The 1st-year performance data collected by State will be obtained and entered in the project database. The following data are expected: FWD data, seasonal ride-quality measurements, distress survey information, load test data from embedded dynamic strain sensors, MIRA and fault meter measurements, joint opening measurements, warping and curling measurements, information from extracted cores, traffic data, and winter deicing activities. Additional data may be desirable (e.g., abrasion/surface wear). These data will be compiled, descriptive statistics calculated (where possible), and comparisons drawn between the performance of test sections and control section (typical State concrete mixture). Based on findings, any recommendations for data collection adjustments (i.e., type, frequency) will be communicated to the TAP. A 1st year performance summary report will be provided to the TAP and key findings will be presented. TAP comments will be integrated into the task deliverable.

Deliverable: Summary report and presentation to the TAP. Progress update during a NRRA monthly meeting or NRRA Research Pays Off.
Date due: November 30, 2023

Task 5: 2nd year performance update

The 2nd-year performance data collected by State will be obtained and entered in the project database and the work will mirror that described in Task 4. Comparisons and findings will include data from the 1st and 2nd years of performance monitoring. A 2nd year performance summary report will be provided to the TAP and key findings will be presented. TAP comments will be integrated into the task deliverable.

Deliverable: Summary report and presentation to the TAP. Progress update during a NRRA monthly meeting or NRRA Research Pays Off.
Date due: September 30, 2024

Task 6: 3rd year performance update

Contractor will visit the project site to observe 3rd-year test section performance with State personnel. The 3rd-year performance data collected by State will be obtained and entered in the project database and the work will mirror that described in Task 4. Comparisons and findings will include data from the 1st, 2nd, and 3rd years of performance monitoring. A final performance summary report will be provided to the TAP and key findings will be presented to the TAP and/or NRRA Research Pays Off. TAP comments will be integrated into the task deliverable.

Deliverable: Summary report and presentation to the TAP. Progress update during a NRRA monthly meeting.
Date due: October 31, 2025

Task 7: Sustainability and resiliency comparison of materials

The primary goal of this task is to compile the environmental data available on each material being evaluated in this study and perform a comparative analysis. A preliminary assessment of the environmental impacts of each mixture used in the construction of the test cells at the MnROAD facility is being conducted under a separate contract. The environmental impacts of conventional concrete paving materials (such as portland cement, portland limestone cement, fly ash, etc.) are available from existing material databases from publicly available sources; however, little to no environmental data may be available on specialty materials, and therefore the project team will have to rely on data from the material suppliers. One potential data source could be Environmental Product Declarations (EPDs) or other environmental data that are published by the material producers. The environmental impact assessment is expected to cover phases from material acquisition through construction for each material based on the data provided. The analysis will focus on the reductions in environmental impacts (based on impact indicators such as global warming potential, ozone layer depletion potential, etc.) that can be realized using concrete mixtures with ASCMs and/or limestone over conventional paving concrete.

Related statistics (e.g., equivalent miles driven, gallons of gasoline saved, etc.) will also be developed to convey information in a non-technical fashion.

The evaluation of the resiliency with regards to a concrete mixture is incomplete without the assessment of the impacts on the entire pavement system. However, other concrete properties, such as reduced shrinkage, reduced permeability, reduction in oxychloride formation potential when exposed to deicing salts, and effective freeze-thaw resistance, may be considered as surrogate indicators of improved resiliency. A comparative analysis of these properties for concrete containing ASCMs and/or limestone and conventional paving concrete will be performed based on the information available from the ongoing study.

Deliverable: Summary report and presentation to the TAP.
Date due: October 31, 2025

Task 8: Final report and tech brief

Contractor will prepare and deliver a draft research report and technical brief document (to aid in implementation) that provides a project overview, data, findings, and conclusions to the TAP. The following chapters are envisioned:

Chapter 1. Introduction, Purpose, and Scope
Chapter 2. Construction Test Results Summary
Chapter 3. Performance Comparison and Findings
Chapter 4. Assessment of Constructability, Sustainability, and Resiliency
Chapter 5. Findings and Conclusions
Appendices: Literature Review Summary, Project Data Summaries, etc.

After addressing TAP comments on the draft documents, a final report and technical brief document will be provided.

Deliverable: Final report and technical brief document for editorial review.
Date due: January 31, 2026

Task 9: Editorial review of final report for publication

Contractor will conduct a comprehensive editorial review to ensure the Final Report and Tech Brief meets State’s publication requirements, aligns with State’s “Plain Language” requirements, and meet provisions of the State of Minnesota’s Accessibility Standards, including those specific to electronic documents. In parallel, Contractor will present the project findings at an annual NRRA meeting.

Deliverable: Final report and technical brief finalized for publication, NRRA annual meeting presentation.
Date due: June 30, 2026

Project team

Email the Project Team
Principal Investigator: Nick Weitzel, Nichols Consulting Engineers, Chtd, NWeitzel@ncenet.com
Technical Liaison: Maria Masten, MnDOT, maria.masten@state.mn.us
Project Technical Advisory Panel (TAP): Contact us to join this TAP

Fatih Bektas, Minnesota State University-Mankato
Dan Gancarz, Illinois Tollway
Alf Gardiner, Braun Intertec
Lieska Halsey, Nebraska DOT
Rita Lederle, University of St. Thomas
Maria Masten, MnDOT (TL)
Somayeh Nassiri, Washington State University
Xijun Shi, Texas State University
Jake Sumeraj, Illinois Tollway
Anthony Torres, Texas State University
Hao Yin, Horizon Engineering Consulting

Related materials

Initial Project proposal (doc), 4/21/2021