Framework for characterizing the time-dependent volumetric properties of aerated cementitious material

摘要

The expansion in cementitious materials can be generally caused by a generation of air bubbles by adding pore generation materials. Even though these materials are beneficial for forming porous structure, they can cause drastic changes in fresh and hardened properties due to their reactions with cementitious materials. To identify these relationships, an accurate measurement of volumetric properties of expansive cementitious materials in the fresh state is needed to be developed. This study proposes a non-contact testing framework for quantitative analysis of time-dependent volumetric properties of expansive cementitious materials using ultrasonic sensor and depth camera during a mixing process. To validate the proposed framework, two types of pore-generation materials-aluminum powder and air-entraining (AE) agent-were used to prepare the aerated cementitious materials as expansive materials. In the estimations of their volume changes, a depth camera-based scheme provided accurate results by scanning entire rough surfaces of testing samples. To suggest the relationship of volume changes with fresh and hardened properties, various tests for analyzing rheological properties, compressive strength, density, and porous microstructure were also performed. All tested results of the aerated cementitious series showed strong correlations with their volume changes, which were measured by a depth camera system. This experimental study indicated the importance and potential of the proposed framework as a practical and reliable means for characterizing time-dependent fresh properties of cementitious materials. (C) 2021 Elsevier Ltd. All rights reserved.