Insights into delayed ettringite formation damage through acoustic nonlinearity

• Published in: Cement and concrete research Vol. 95; pp. 1 - 8
• Main Authors: Rashidi, Mehdi, Paul, Alvaro, Kim, Jin-Yeon, Jacobs, Laurence J., Kurtis, Kimberly E.
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01-05-2017; Elsevier BV
• Subjects: Acoustic resonance; Acoustics; Curing; Damage detection; Delayed ettringite formation (DEF) (C); Ettringite; Expansion (C); Microcracking (B); Mortars (material); Nonlinear acoustics; Nonlinearity; Thermal treatment (A); Microcracking (B); Expansion (C); Nonlinear acoustics; Delayed ettringite formation (DEF) (C); Thermal treatment (A)
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2017.02.004

A nonlinear acoustic approach for the detection and quantification of damage in mortars affected by delayed ettringite formation (DEF) is used to provide insights into the degradation mechanism at the microscale and its correlation with bulk expansion. The nonlinear acoustic technique, Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS) successfully differentiates among mortars experiencing various amounts of expansion and microstructurally-evident distress due to DEF. Results indicate that mortars are damaged both during the early-age high-temperature curing and subsequent 23°C-limewater curing. However, the time of initiation of expansion occurs earlier for samples showing higher damage level (as measured by average nonlinearity parameter) at the end of high-temperature curing. During the exposure period, the ratio of absolute maximum to the initial average nonlinearity parameter of DEF-affected mortars varies from 3 to 30, indicating that the DEF damage can increase more than an order of magnitude greater than that experienced during the high-temperature curing.