Dr. Kalliontzis is an active member of the following Committees and Organizations:
Associate Member of American Concrete Institute (ACI) Committee 239: Ultra-High-Performance Concrete
Voting Member of ACI Subcommittee 239-C: Structural Design on UHPC
Associate Member of ACI Committee 357: Offshore and Marine Concrete Structures
Associate Member of ACI Committee 550: Precast Structures—Joint ACI-ASCE
Chair of ACI Subcommittee 550: PRESS FRAME
Voting Member of The Masonry Society (TMS) Research Committee
Voting Member of The Masonry Society (TMS) Reinforcement & Connectors (RC) Subcommittee
Chair of High-Strength Reinforcing Bar (HSRB) Task Group for The Masonry Society (TMS)
Member of the University Marine Energy Research Community (UMERC)
Member of the Texas Masonry Council (TMC) Industry Development and Education Alliance (IDEA) Committee
Member of StEER Network
Other Professional Service and Outreach Activities:
Chair of the Student Competition for the 2026 4th International Interactive Symposium on Ultra-High Performance Concrete (4IISUHPC).
Member of the Scientific Committee for the 2026 International Masonry Conference.
Gave several expert-opinion interviews for the 2024 Houston Derecho event.
Member of the Scientific Committee for the 2023 3rd International Interactive Symposium on Ultra-High Performance Concrete (3IISUHPC).
Invited External Examiner for the Final Thesis Defense of a PhD Candidate in the University of Alberta, Canada (2025).
Participated in the NICHE Workshop “Designing the World’s Largest Wind-Wave Research Facility” DesignSafe-CI (2024).
Organized UH Educational Masonry Days (2022-2023).
Participated in several reconnaissance (PVRR and EARR) reports of StEER for historic tropical storms and hurricanes (2022-2024).