Correlation between electrical resistivity and compressive strength of stabilized dredged sediment for early quality control

Quality control of stabilized dredged sediment (DS) presents significant challenges due to its high-water content. Nowadays, many in-situ and laboratory tests have been used to evaluate the quality of treated DS, and the dominant method is 28-day unconfined compressive strength that can be done on undisturbed samples from the field and the laboratory. Due to the waiting period to get results from the tests and the destructive nature of tests, it is desirable to use a non-destructive method to control the quality of stabilized DS at an early stage. This study suggests electrical resistivity measurement as a non-destructive and fast method for evaluating the quality of stabilized DS. Dredged sediment samples from Göta älv, Gothenburg, with different water contents, were stabilized with different water-binder ratios at the laboratory. The quality of treated sediments was evaluated by uniaxial compressive strength (UCS) after 28-day of stabilizing, while strength development during the curing period was checked with a free-free resonance test at 7, 14, and 28 days of curing, and the electrical resistivity (ER) measurement monitored on some samples during the curing period. The results indicate that a combination of UCS tests and ER measurements can be utilized early stage evaluation of the quality of stabilized DS already after 24, 48 or 72 h. According to the results, after 24 h of hydration, the electrical resistivity was less than 1 Ωm. After 72 h of hydration, the resistivity was between 1 to 2.5 Ωm, which shows the development of strength. The 28-day strength varied from 0.25 MPa to 2 MPa while the resistivity varied between 3 Ωm to 22 Ωm. The observed variations in resistivity and compressive strength can be attributed to differences in the water-to-binder ratio across the samples.

This approach offers a practical, non-destructive method for detecting early quality issues of stabilized DS, enabling quicker decision-making and potentially reducing project timelines and costs while maintaining the integrity and safety of construction projects involving stabilized dredged sediments.