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.
Bibliographical noteFunding Information:
This material is based upon work supported by the National Science Foundation (NSF) under Grant No. CMMI-1234035 and Georgia Department of Transportation (GDOT) under Research Project No. FHWA-GA-15-1315. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF or GDOT.
© 2017 Elsevier Ltd
- Delayed ettringite formation (DEF) (C)
- Expansion (C)
- Microcracking (B)
- Nonlinear acoustics
- Thermal treatment (A)