Monday, March 30, 2026 10:00 AM - 11:00 AM, International B
This mini-session, hosted by ACI Committee 240 – Pozzolans, will highlight current student research on the use of natural pozzolans as supplementary cementitious materials. Researchers will present short talks featuring new findings on pozzolanic materials characterization methods, processing strategies, and performance outcomes. The session aims to connect emerging researchers with industry and academic professionals while showcasing the most recent advances and ongoing challenges in developing sustainable pozzolanic materials for concrete.
Learning Objectives:
(1) Identify recent advances in the characterization, activation, and performance evaluation of natural pozzolans used as supplementary cementitious materials (SCMs);
(2) Discuss the influence of mineralogical composition and/or processing methods on the pozzolanic reactivity and performance of natural pozzolans in concrete;
(3) Learn about current research approaches and testing methods for assessing the reactivity, strength contribution, and long-term stability of natural pozzolans in blended cements;
(4) Recognize emerging challenges, research gaps, and opportunities for scaling the use of natural pozzolans to meet sustainability and performance goals in modern cementitious systems.
Wood Fly Ash as a Supplementary Cementitious Material: Laboratory-scale Experiements to Field Applications
Presented By: Shahria Alam
Affiliation: University of British Columbia
Description: With the closure of coal-fired power plants worldwide, the supply of coal fly ash (CFA) is declining significantly, raising the risk of future unavailability. CFA has been an essential addition to cementitious materials as a supplementary cementitious material (SCM) due to its pozzolanic activity and contribution to reducing the carbon footprint of cement. In search of an alternative to CFA, we have been conducting research on wood fly ash (WFA), a byproduct generated during the production of green biomass energy. With the closure of coal-fired power plants and the increase in biomass-fed energy production, WFA is abundant in North America, and its disposal has become a concern. WFA is derived from burning waste biomass feedstock; therefore, it is a sustainable addition to the cement industry. By conducting characterization tests on WFA and examining the properties of cementitious materials containing WFA as an SCM, we have observed its participation in pozzolanic activity in cementitious mixes. The promising performance of WFA-blended cement concrete in the lab led our research to field applications. The concrete was mixed at a batch plant, where three mixes with 0%, 15%, and 30% cement replacement were used to produce real-life slabs and lock blocks. The 15% cement-replacement mix performed comparably to the control. The specimens are being monitored to determine the effect of weather exposure on their properties. The results of this study can serve as a guide for updating current standards by including WFA as a pozzolanic material.
Lessons Learned From Fine Tuning Water Reducers for Improving Performance of Concrete with Natural Pozzolans
Presented By: Mark Niemuth
Affiliation: Cemex
Description: With the growing use of natural pozzolans in the U.S., there is an increasing need to identify water reducers specifically optimized for these materials. Water reducers are used in the vast majority of concrete mixtures and play a critical role in meeting ever-evolving performance demands. However, their efficiency and behavior can vary significantly depending on the binder system—especially when incorporating or switching between different sources of natural pozzolans. This presentation will explore key lessons learned in the search for more effective water-reducing admixtures tailored to natural pozzolans. It will highlight plastic concrete properties performance considerations beyond slump. Various evaluation techniques will be discussed to help better assess admixture performance in pozzolan-rich systems.
Performance Evaluation of CSA Blends for Fast-Track Repairs: CSA Cement Incorporated with Slag and Glass Powder
Presented By: Daniel Akerele
Affiliation: University Of Washington
Description: Recent efforts to achieve sustainability objectives in the concrete industry have necessitated the use of alternative cements, such as calcium sulfoaluminates (CSA), particularly in accelerated repair scenarios. However, these cements often struggle to balance early-age strength with other parameters such as later-age strength, rheology, long-term durability, and sustainability required for exposed structures. This macro-scale study examines the use of supplementary cementitious materials (slag and glass powder) to enhance sustainability initiatives and potentially mitigate the drawbacks associated with ordinary CSA. Fresh, mechanical, and durability properties were assessed through rigorous laboratory testing via relevant ASTM and AASHTO standards. Results show improved working time and fresh properties. CSA+30% slag+10% glass powder, although showing significantly lower shrinkage and a compressive strength of over 2500 psi at 4 hours, struggled to develop sufficient later-age strength (greater than 5000 psi). CSA+30% glass powder, however, showed better mechanical properties compared to the slag blend, albeit with slightly more shrinkage. CSA blends also showed comparable permeability and freeze-thaw performance to ordinary CSA. Additionally, incorporating SCM in CSA lowers the Coefficient of Thermal Expansion relevant to repair applications. Field-scale validation demonstrates that CSA blend can be successfully used in full-depth repair scenarios. These findings are important to exploring sustainable options for repair applications and helping engineers and DOTs to make informed decisions for fast-track infrastructure rehabilitation and construction. Additionally, it provides more insight into the properties of CSA cements, especially the nuanced behavior and trade-offs with different blends and systems.