Abstract
This paper presents an analysis of the damage propagation features of the pore structure of natural pumice lightweight aggregate concrete (LWC) under freeze-thaw cyclic action. After freeze-thaw cycling, we conducted nuclear magnetic resonance (NMR) tests on the concrete and acquired the porosity, distribution of transverse relaxation time T 2 , and magnetic resonance imaging (MRI) results. The results showed the following. The T 2 distribution of the LWC prior to freeze-thaw cycling presented four peaks representative of a preponderance of small pores. After 50, 100, 150, and 200 freeze-thaw cycles, the total area of the T 2 spectrum and the porosity increased significantly. The MRI presented the changing spatial distribution of pores within the LWC during freeze-thaw cycling. Ultrasonic testing technology was applied simultaneously to analyze the NMR results, which verified that the new NMR technology demonstrated high accuracy and practicability for research regarding freeze-thaw concrete damage.
Highlights
RESUMEN: Análisis por resonancia magnética nuclear del deterioro en hormigón con piedra pómez tras ciclos hielo-deshielo.En este trabajo se analiza la propagación de los daños que se producen en la estructura porosa de hormigón aligerado a base de piedra pómez natural sometido a la acción cíclica de hielo-deshielo
Due to seasonal changes and the diurnal cycle, the concrete materials of hydraulic structures sustain the physical weathering caused by freeze-thaw cycling, which results in extension and propagation in the internal micro-fractures of the concrete
To eliminate the effects of moisture evaporation on the test results, the moisture was wiped from the surface of the samples upon being removed, and each sample was wrapped in a preservative film for nuclear magnetic resonance (NMR) analysis
Summary
To eliminate the effects of uneven freeze-thawing at the ends, we removed a 100 mm × 100 mm × 170 mm section at both ends of the test piece. We further removed a 30 mm thick perimeter from the outer surface of the remaining section, leaving a residual core sample with dimensions of about 40 mm × 40 mm × 60 mm. This process was designed to eliminate uneven distributions of the effects of uneven freeze-thawing on the formed surface and underside aggregate. We conducted NMR analysis on the core samples after different numbers of freezethaw cycles. To eliminate the effects of moisture evaporation on the test results, the moisture was wiped from the surface of the samples upon being removed, and each sample was wrapped in a preservative film for NMR analysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
