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 February 2026 is Souvik Roy, a recent doctoral graduate and current Postdoctoral Scholar PhD student at University of California, Davis (California, USA).
BIO:
Souvik Roy graduated from the University of California, Davis, in September 2025 with a Ph.D. in Civil and Environmental Engineering. He is currently a Postdoctoral Scholar at the UC Pavement Research Center, where he works on low-carbon concrete and pavement materials, focusing on biomass-based cement replacement through a combination of laboratory research, field trials, and collaboration with industry partners.
TITLE: Towards Lower-Carbon Concrete Pavements with Biochar as Supplementary Cementitious Materials
Performance of concrete pavements relies heavily on Portland cement as the binder; however, cement production is responsible for 7-10% of the global carbon dioxide emissions. Parallelly, large quantities of agricultural and forestry residues, such as rice hulls and wood waste, are generated each year, particularly in regions like the Western United States, where these materials are often underutilized and can create wildfire hazards and/or disposal challenges. Biochar, a carbon-rich material produced from the thermochemical conversion of these residues, has the potential to reduce cement demand in concrete while acting as a long-term carbon sink. However, biochar properties vary widely depending on feedstock and production method, and it is not well established how different biochars perform when used as partial cement replacement in concrete pavement applications.
The objective of this research is to evaluate how biochar source and chemistry influence its suitability as a partial cement replacement in concrete pavements and interlocking concrete pavers (ICP). In particular, the study distinguishes between reactive biochars that can contribute to cement hydration and inert biochars that function primarily as fillers.
To address this objective, biochars produced from rice hulls and wood residues were evaluated at laboratory and production scales. Rice-hull biochars were found to contain reactive silica and exhibited pozzolanic behavior, allowing them to function as supplementary cementitious materials in pavement-grade concrete without compromising early-age performance. In contrast, wood-derived biochars consisted primarily of stable carbon (often exceeding 90% by weight) and behaved as inert materials. Despite this, concrete pavers with up to 10% cement replacement using wood biochar demonstrated acceptable early-age performance due to filler and particle-packing effects. These results indicate that while reactive biochars are better suited for structural pavement concrete, inert biochars may still be viable for ICPs and other applications with lower performance demands.
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(b)
Figure 1: Freshly produced interlocking concrete pavers in the factory (a) 100% cement pavers, (b) 90% cement-10%wood biochar pavers.
Figure 2: Factory-produced interlocking concrete pavers after 1.5 years: left-100% cement pavers and right-90% cement-10% wood biochar pavers.
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