Dr. Kalliontzis is an active member in 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 and Corresponding Member in the Reinforcement & Connectors (RC) Subcommittee

• Chair of High-Strength Reinforcing Bar (HSRB) Task Group for 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

Dr. Kalliontzis has served in the Scientific Committee for the 3rd International Interactive Symposium on Ultra-High Performance Concrete (UHPC).

He has organized the first and second UH Masonry Days for 2022 and 2023.

He has participated in several reconnaissance (PVRR and EARR) reports of StEER for historic tropical storms and hurricanes.