Nuclear magnetic resonance analysis of concrete-lined channel freeze-thaw damage

The channel lining of Inner Mongolia hetao irrigation is set in the research background, which was used by natural pumice concrete as the raw material. In the present study, based on the existing research and analysis methods of air entraining natural pumice concrete freeze-thaw damage, a nuclear magnetic resonance detection technique was introduced. From the research of essence of freeze-thaw coupling-induced concrete damage in saline solution, natural pumice concrete porosity and transversal relaxation time T-2 spectral parameters were used as criteria. Nuclear magnetic resonance imaging (NMRI) technology, an intuitive method, was used to quantitatively determine the freeze-thaw damage. Furthermore, the nuclear magnetic resonance results were compared and demonstrated, combined with ultrasonic testing methods and the capillary water absorption test. Based on the study results, it may be concluded that four peaks were present in the T-2 distribution of air entraining natural lightweight aggregate concrete after 200 cycles of freezing and thawing, the porosity increased with the increase of the air-entraining agent, and T-2 spectrum area increased. The freeze-thaw cycle of frost resistance was improved by a moderate quantity of air entraining agent. An excess of the air-entraining agent caused large pores, which accelerated the freeze-thaw damage. NMRI was used to analyze the pore damage propagation characteristics of the air-entraining concrete, which provides information for freezing thawing damage analysis of concrete, and also represents the unique advantages of NMR techniques. (C) 2015 The Ceramic Society of Japan. All rights reserved.