A set of coupling experimental instrument was designed to study the transport properties of chloride ion in concrete under simultaneous coupling action of fatigue load and environmental factors. Firstly the water-satu...A set of coupling experimental instrument was designed to study the transport properties of chloride ion in concrete under simultaneous coupling action of fatigue load and environmental factors. Firstly the water-saturated performance of modem concrete was investigated, then diffusion performance of chloride ion under different stress levels and different temperature were studied respectively; meanwhile, the time- dependent behavior of the chloride ion diffusion in concrete was also researched. The results showed that the saturation degree of concrete can reach as high as 99%. Besides, diffusion coefficient of chloride ion increased with increasing of the stress level and temperature, and when the stress level and temperature are at 0.6 and 60 ℃ respectively, the diffusion coefficient is 6.3 ×10 -14 m2/s, moreover the diffusion coefficient of chloride ion in concrete decreased with time under the simultaneous coupling action of fatigue load and environment factors.展开更多
Nanoindentation technique was adopted to investigate the chemomechanical properties change of hardened cement paste before and after carbonation.It was found that the mean elastic modulus and mean hardness obviously i...Nanoindentation technique was adopted to investigate the chemomechanical properties change of hardened cement paste before and after carbonation.It was found that the mean elastic modulus and mean hardness obviously increase after the carbonation reaction.Specifically,the probability of the elastic modulus showed a sharp reduction for the elastic modulus at the range of 7-34 and 83-160 GPa,in comparison of a large increase for the elastic modulus between 34-83 GPa.For the same reason,the probability of the hardness showed a large decrease when the hardness fell within 0.15-1.75 and 4.15-8.20 GPa and a dramatic increase for the hardness at the range of 1.75-4.15 GPa.In addition,low density C-S-H was affected by the carbonation degradation more seriously than high density C-S-H.The carbonation reaction led to distinct decrease of the number and size of unhydrated cement paste particles.展开更多
The transport performance of chloride ion in slag cement mortar was investigated experimentally. In the self-designed experiment, fatigue loading was coupled simultaneously with ion transportation process, the diffusi...The transport performance of chloride ion in slag cement mortar was investigated experimentally. In the self-designed experiment, fatigue loading was coupled simultaneously with ion transportation process, the diffusion law of chloride ion was obtained by titration and the AE (acoustic emission) technique was employed to detect the real-time damage distribution in the mortar specimen. The results for fatigue stress levels of 0.3, 0.4 and 0.5 and slag contents of 0, 10%, 30% and 50% showed that fatigue loading accelerated the diffusion of chloride ion in mortar and the acceleration effect increased with the increase in stress levels. Slag addition was found to improve anti-chloride ion erosion performance effectively with the best substitution level at 30%, because the inhibition effect of slag on chloride ion diffusion diminished when the slag content exceeded 30%. The comparative experiments indicated that dynamic load has a significant effect on the transport performance of chloride ion in slag cement mortar.展开更多
基金Supported by the Scientif ic Research Foundation of Graduation School of Southeast University(No.YBjj1129)the National Natural Science Foundation of China(No. 51078081)Ph D Programs Foundation of Ministry of Education of China(No. 200802861080)
文摘A set of coupling experimental instrument was designed to study the transport properties of chloride ion in concrete under simultaneous coupling action of fatigue load and environmental factors. Firstly the water-saturated performance of modem concrete was investigated, then diffusion performance of chloride ion under different stress levels and different temperature were studied respectively; meanwhile, the time- dependent behavior of the chloride ion diffusion in concrete was also researched. The results showed that the saturation degree of concrete can reach as high as 99%. Besides, diffusion coefficient of chloride ion increased with increasing of the stress level and temperature, and when the stress level and temperature are at 0.6 and 60 ℃ respectively, the diffusion coefficient is 6.3 ×10 -14 m2/s, moreover the diffusion coefficient of chloride ion in concrete decreased with time under the simultaneous coupling action of fatigue load and environment factors.
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2009CB623200)the Scientific Research Foundation of the Graduate School of Southeast University (Grant No. YBJJ1113)
文摘Nanoindentation technique was adopted to investigate the chemomechanical properties change of hardened cement paste before and after carbonation.It was found that the mean elastic modulus and mean hardness obviously increase after the carbonation reaction.Specifically,the probability of the elastic modulus showed a sharp reduction for the elastic modulus at the range of 7-34 and 83-160 GPa,in comparison of a large increase for the elastic modulus between 34-83 GPa.For the same reason,the probability of the hardness showed a large decrease when the hardness fell within 0.15-1.75 and 4.15-8.20 GPa and a dramatic increase for the hardness at the range of 1.75-4.15 GPa.In addition,low density C-S-H was affected by the carbonation degradation more seriously than high density C-S-H.The carbonation reaction led to distinct decrease of the number and size of unhydrated cement paste particles.
基金supported by the Scientific Research Foundation of Graduate School Southeast University (Grant No. YBJJ1129)the National Natural Science Foundation of China (Grant No. 5107808)the National Basic Research Program of China ("973" Project) (Grant No. 2009CB326200)
文摘The transport performance of chloride ion in slag cement mortar was investigated experimentally. In the self-designed experiment, fatigue loading was coupled simultaneously with ion transportation process, the diffusion law of chloride ion was obtained by titration and the AE (acoustic emission) technique was employed to detect the real-time damage distribution in the mortar specimen. The results for fatigue stress levels of 0.3, 0.4 and 0.5 and slag contents of 0, 10%, 30% and 50% showed that fatigue loading accelerated the diffusion of chloride ion in mortar and the acceleration effect increased with the increase in stress levels. Slag addition was found to improve anti-chloride ion erosion performance effectively with the best substitution level at 30%, because the inhibition effect of slag on chloride ion diffusion diminished when the slag content exceeded 30%. The comparative experiments indicated that dynamic load has a significant effect on the transport performance of chloride ion in slag cement mortar.
