STUDENT SPOTLIGHT: Each month, or every other month, a student will provide a 1-page illustrated abstract of the research they are currently conducting. This is a wonderful opportunity for the student, for our International Society for Concrete Pavements (ISCP) Members, and for the transferring and sharing technology/research through our concrete paving industry.
The ISCP “STUDENT RESEARCH SPOTLIGHT” for April 2025 is Makorogo Barugahare, a PhD candidate in Civil Engineering at the University of Alabama (Tuscaloosa, USA).
BIO:
Makorogo Barugahare is a PhD candidate in Civil Engineering (Structural Engineering and Materials) at the University of Alabama, under the supervision of ISCP Treasurer Dr. Armen Amirkhanian. His research focuses on developing performance-based strategies for safely incorporating non-compliant aggregates into concrete. These materials—often excluded due to issues such as ASTM C33 gradation non-conformance, chemical contamination (chlorides and sulfates), or alkali-silica reactivity (ASR)—represent an underutilized resource in regions where compliant aggregates are increasingly scarce. By addressing the deterioration mechanisms that limit their use, his work advances materials sustainability and broadens the range of viable aggregates for durable, resilient infrastructure.
TITLE:
Silane-Based Mitigation of ASR in Concrete: Aggregate and Surface Treatment Approaches
Overview
Alkali–silica reaction (ASR) remains a critical durability concern in concrete infrastructure, with no definitive mitigation strategy. This study evaluates two silane-based strategies to enable the use of ASR-susceptible aggregates: (1) pre-treatment of reactive aggregates to suppress silica–alkali interaction at the particle interface, and (2) surface sealing to limit moisture ingress and maintain internal relative humidity below the ASR activation threshold.
Methodology
Specimens incorporating ASR-reactive aggregates were prepared under three treatment conditions: untreated, aggregates pre-coated with silane (30–90 mL/kg), and surface-sealed concrete (100–200 g/m²). Mitigation performance was evaluated using ASTM C1260 (14-day mortar bar test), AASHTO T380 (56-day miniature prism test), ASTM C1293 (1-year prism test), and an autoclave acceleration protocol (5–28 days). Multiple aggregate sources enabled assessment across varying reactivity levels, while different test methods evaluated performance under diverse environmental conditions.
Results
Aggregate Pre-Treatment
Pre-coating reactive aggregates with silane (30–90 mL/kg) generally yielded modest expansion reductions in short-term tests (AASHTO T380, autoclave; data not shown; see Figure 1). Sample labels (e.g., D-60, M-60) denote aggregate type and dosage; MS and MD indicate single (100 g/m²) and double (200 g/m²) surface treatments. In the long-term ASTM C1293 test, expansion remained well above acceptable limits, suggesting silane degradation and limited long-term efficacy of aggregate treatment alone.
Surface Treatment
Silane surface treatment markedly reduced expansion in ASTM C1293: one specimen remained below the reactivity threshold, two marginally exceeded it, and one exhibited moderate expansion—though substantially lower than untreated and aggregate treated samples (Figure 2; other specimens not shown for brevity). Note: Treatments in Figure 2 were applied after 4 h of air-drying at room temperature with internal humidity likely sufficient to sustain ASR despite surface sealing.
In short-term tests, surface-treated specimens remained non-reactive when treatments were applied after oven-drying (4 h or 5 days at 38 °C) to reduce internal humidity below the ASR activation threshold (about 80% as reported in most studies). Sample labels (e.g., M-D 4h, M-D 5d) denote oven-drying durations. Similar long-term reductions are anticipated, consistent with trends observed in Figure 1.
Conclusion
Silane surface treatments, when applied under controlled internal humidity, significantly reduce ASR-induced expansion. Aggregate pre-treatment showed limited durability. These findings confirm internal relative humidity as critical in ASR kinetics and position surface treatments as a practical, scalable strategy for performance-based ASR mitigation in concrete infrastructure.
ISCP would like to feature a “STUDENT RESEARCH SPOTLIGHT” each month, or every other month. If you would like to nominate a student, or if you are a student and would like to nominate yourself or a colleague, please send ISCP an email to: newsletter@concretepavements.org
ALL SPOTLIGHTS:
DECEMBER 2021—Inaugural: Katelyn Kosar, PhD Student-Department of Civil and Environmental Engineering, University of Pittsburgh (Pitt): www.concretepavements.org/2021/12/14/new-at-iscp-student-research-spotlight/
JANUARY 2022: Aniruddha Baral, Ph.D. Candidate-Department of Civil and Environmental Engineering, University of Illinois-Urbana-Champaign: www.concretepavements.org/2022/01/15/student-research-spotlight-jan-2022/
FEBRUARY 2022: Jordan Ouellet, Tech, BEng, MASc, PhD Candidate, Teaching and Research Assistant, University of Illinois at Urbana-Champaign: www.concretepavements.org/2022/02/26/student-research-spotlight-february-2022/
MARCH 2022: Sampath Kumar Pasupunuri, Ph.D. candidate, Pavement Engineering-School of Civil Engineering, University of Nottingham, UK: https://www.concretepavements.org/2022/03/31/student-research-spotlight-march-2022/
APRIL 2022: Anupam B R, Pursuing his doctorate-Indian Institute of Technology Bhubaneswar, India: https://www.concretepavements.org/2022/04/15/student-research-spotlight-april-2022
MAY 2022: Andréia Posser Cargnin, Ph.D. Candidate, Polytechnic School, University of São Paulo (São Paulo, Brazil): https://www.concretepavements.org/2022/05/09/student-research-spotlight-may-2022/
JUNE 2022: Charles Donnelly, Ph.D. Candidate, Department of Civil and Environmental Engineering, University of Pittsburgh (Pittsburgh, USA): https://www.concretepavements.org/2022/06/24/student-research-spotlight-june-2022/
JULY 2022: Amir Malakooti, Ph.D. Candidate, Department of Civil and Environmental Engineering, Iowa State University (Ames, Iowa, USA): https://www.concretepavements.org/2022/07/30/student-research-spotlight-july-2022/
AUGUST 2022: Haoran Li, Ph.D. Candidate, Department of Civil and Environmental Engineering, University of Pittsburgh (Pittsburgh, USA): https://www.concretepavements.org/2022/08/24/student-research-spotlight-august-2022/
SEPTEMBER 2022: Sumit Nandi, Ph.D. Candidate, Department of Civil Engineering, Indian Institute of Technology Roorkee (Roorkee, India): https://www.concretepavements.org/2022/09/18/student-research-spotlight-september-2022/
OCTOBER 2022: Eric Ribeiro da Silva, Ph.D. Candidate, Department of Civil Engineering, Polytechnic School of the University of São Paulo (São Paulo, Brazil): https://www.concretepavements.org/2022/10/20/student-research-spotlight-october-2022/
NOVEMBER 2022: Zachary Brody, Ph.D. Candidate, Department of Civil and Environmental Engineering, University of Pittsburgh (Pittsburgh, USA): https://www.concretepavements.org/2022/11/18/student-research-spotlight-november-2022/
DECEMBER 2022: Jesús Castro Pérez, Ph.D. Candidate, Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign (Urbana, USA): https://www.concretepavements.org/2022/12/17/student-research-spotlight-december-2022/
JANUARY 2023: Dan King, Ph.D. Candidate, Department of Civil and Environmental Engineering, Iowa State University (Ames, USA): https://www.concretepavements.org/2023/01/26/student-research-spotlight-january-2023/
FEBRUARY 2023: Kathryn Kennebeck, Ph.D. Candidate, Department of Civil and Environmental Engineering, University of Pittsburgh (Pittsburgh, USA): https://www.concretepavements.org/2023/02/28/student-research-spotlight-february-2023/
MARCH 2023: Sinan Kefeli, Ph.D. Candidate, Department of Civil and Environmental Engineering, Iowa State University (Ames, USA): https://www.concretepavements.org/2023/03/13/student-research-spotlight-march-2023/
APRIL 2023: Niwesh Koirala, Ph.D. Candidate, Department of Civil and Environmental Engineering, Texas Tech University (Lubbock, USA): https://www.concretepavements.org/2023/04/07/student-research-spotlight-april-2023/
MAY 2023: Christian A. Sabillon, Ph.D. Candidate, The University of Texas at Austin (Austin, Texas, USA): https://www.concretepavements.org/2023/05/05/student-research-spotlight-may-2023/
JUNE 2023: Saima Yaqoob, Ph.D. Candidate, KTH (the Royal Institutes of Technology) (Stockholm, Sweden): https://www.concretepavements.org/2023/06/15/student-research-spotlight-june-2023/
JULY 2023: Ricardo Hungria, Ph.D. Candidate, Louisiana State University (Baton Rouge, USA): https://www.concretepavements.org/2023/07/11/student-research-spotlight-july-2023/
AUGUST 2023: Megan Darnell, Ph.D. Candidate, University of Pittsburgh (Pittsburgh, USA): https://www.concretepavements.org/2023/08/07/student-research-spotlight-august-2023/
SEPTEMBER 2023: Jitendra Patel, Ph.D. Candidate, Alma Mater Studiorum – Università di Bologna (Italy): https://www.concretepavements.org/2023/09/05/student-research-spotlight-september-2023/
OCTOBER 2023: Omar K. Omar, Ph.D. Candidate, Louisiana State University (Baton Rouge, USA): https://www.concretepavements.org/2023/10/05/student-research-spotlight-october-2023/
NOVEMBER 2023: Mason Smetana, Ph.D. Candidate, University of Pittsburgh (Pittsburgh, USA): https://www.concretepavements.org/2023/11/07/student-research-spotlight-november-2023/
DECEMBER 2023: Avinash Jha, M.Tech Student, Indian Institute of Technology Gandhinagar (India): https://www.concretepavements.org/2023/12/10/student-research-spotlight-december-2023/
JANUARY 2024: Matthew Sheffield, Ph.D candidate, University of North Carolina at Charlotte (Charlotte, USA): https://www.concretepavements.org/2024/01/13/student-research-spotlight-january-2024/
FEBRUARY 2024: Chintada Chandrasekhar, Ph.D candidate, Indian Institute of Technology Roorkee (Roorkee, India): https://www.concretepavements.org/2024/02/08/student-research-spotlight-february-2024/
MARCH 2024: Subham Jain, Ph.D candidate, Indian Institute of Technology Kanpur (Kanpur, India): https://www.concretepavements.org/2024/03/08/student-research-spotlight-march-2024/
APRIL 2024: Etienne Beya Nkongolo, Ph.D candidate, University of Missouri Kansas-City (Kansas City, USA): https://www.concretepavements.org/2024/04/11/student-research-spotlight-april-2024/
MAY 2024: Shivani Sharma, Ph.D candidate, Indian Institute of Technology Gandhinagar (Gandhinagar, India): https://www.concretepavements.org/2024/05/14/student-research-spotlight-may-2024/
JUNE 2024: Isaac Oyawoye, Ph.D candidate, University of North Carolina at Charlotte (Charlotte, USA): https://www.concretepavements.org/2024/06/16/student-research-spotlight-june-2024/
JULY 2024: Tianzhen Li, Ph.D candidate, Xi’an Jiaotong-Liverpool University and the University of Liverpool (Suzhou, China): https://www.concretepavements.org/2024/07/04/student-research-spotlight-july-2024/
AUGUST 2024: Andrés Gabriel César Torres, Ph.D candidate, Polytechnic School of the University of São Paulo (São Paulo, Brazil): https://www.concretepavements.org/2024/08/06/student-research-spotlight-august-2024/
SEPTEMBER 2024: Bhabya Thakur, Masters student, Indian Institute of Technology Gandhinagar (Gandhinagar, India): https://www.concretepavements.org/2024/09/21/student-research-spotlight-september-2024/
OCTOBER 2024: Alberto Castillo, PhD student, Purdue University (West Lafayette, USA): https://www.concretepavements.org/2024/10/22/student-research-spotlight-october-2024/
NOVEMBER 2024: Salman Amin, MSE student, Youngstown State University (Youngstown, USA): https://www.concretepavements.org/2024/11/07/student-research-spotlight-november-2024/
DECEMBER 2024: Lara Guizi Anoni, PhD student, University of São Paulo (São Paulo, Brazil): https://www.concretepavements.org/2024/12/05/student-research-spotlight-december-2024/
JANUARY 2025: Nischal Pokhrel, MSE student, Youngstown State University (Youngstown, USA): https://www.concretepavements.org/2025/01/11/student-research-spotlight-january-2025/
FEBRUARY 2025: Saranga Premarathna, PhD candidate, Technical University of Delft (Delft, The Netherlands): https://www.concretepavements.org/2025/02/13/student-research-spotlight-february-2025/
MARCH 2025: Anushka Khachi, Masters student, Indian Institute of Technology Gandhinagar (Gandhinagar, India): https://www.concretepavements.org/2025/03/18/student-research-spotlight-march-2025/