Experimental study on concrete expansion performance and cracking time under SCDA pressure using DOFS technology.

In order to study the distribution of strain in concrete at different times and positions under internal expansion pressure, experiments with a soundless chemical demolition agent (SCDA) were conducted on cubic concrete with one hole, and Distributed Optic Fiber Sensing (DOFS) technology, in comparison to a static strain tester, was used to measure the expansion strain of concrete, evaluate its cracking time, and theoretically calculate the expansion tensile stress at the cracking time. The test results show that there was a linear correlation between strain with time but a negative correlation with distance from the hole. Additionally, the strain-position peak shapes at different times aligned with classical mechanics principles. Under pressure from SCDA in the central hole (40 mm in diameter), the cracking time of a 150-mm C40 cubic concrete was evaluated as 73.3 min. DOFS technology exhibits higher accuracy and sensitivity than the static strain tester in evaluating the strain and cracking time of concrete.It can also reflect the spatial distribution information of strain, which can be applied to research on various expansion materials and structures.