We prepared concretes（RC0, RC30, and RC100） with three different mixes. The poresize distribution parameters of RAC were examined by high-precision mercury intrusion method（MIM） and nuclear magnetic resonance（NMR...We prepared concretes（RC0, RC30, and RC100） with three different mixes. The poresize distribution parameters of RAC were examined by high-precision mercury intrusion method（MIM） and nuclear magnetic resonance（NMR） imaging. A capillary-bundle physical model with random-distribution pores（improved model, IM） was established according to the parameters, and dry-shrinkage strain values were calculated and verified. Results show that in all pore types, capillary pores, and gel pores have the greatest impacts on concrete shrinkage, especially for pores 2.5-50 and 50-100 nm in size. The median radii are 34.2, 31, and 34 nm for RC0, RC30, and RC100, respectively. Moreover, the internal micropore size distribution of RC0 differs from that of RC30 and RC100, and the pore descriptions of MIM and NMR are consistent both in theory and in practice. Compared with the traditional capillary-bundle model, the calculated results of IM have higher accuracy as demonstrated by experimental verifi cation.展开更多
This paper presents the results of an experimental survey on the potential application of DARC （dry asphalt rubber concrete） in rail superstructure, within sub-ballast layers by measuring its damping and mechanical ...This paper presents the results of an experimental survey on the potential application of DARC （dry asphalt rubber concrete） in rail superstructure, within sub-ballast layers by measuring its damping and mechanical properties. Based on the environmental friendly point of view the DARC has the significant advantage as the backfill material of sub-ballast layer because the rubber comes from the waste tires of truck and its usage can results a significant recycling of non-biodegradable wastes. After a preliminary mix-design of several DARCs, with different rubber content that confirmed by using the Marshall test, the stiffness modulus and damping ratio both of a standard bituminous mixture and of dry asphalt rubber concrete with a rubber content equal to 1.5% were determined using the four points bending device. The experimental results were compared and a numerical analysis by means of a 2D lumped mass model was developed in order to evaluate the different performance within the rail superstructure in terms both of the deflection and of the pressure on sub-grade. Both the results on the mechanical and dissipative properties of the DARC and the mechanical behavior of the correlate rail superstructure encourage the authors to continue the research on the application of such material for sub-ballast layers.展开更多
基金Funded by the National Natural Science Foundation of China(51202304)the China Postdoctoral Science Foundation(2014M552320)+1 种基金Scientific,the Technological Talents’Special Funds of Wanzhou District and Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJ1401016)the Youth Project of Chongqing Three Gorges College(13QN-20)
文摘We prepared concretes（RC0, RC30, and RC100） with three different mixes. The poresize distribution parameters of RAC were examined by high-precision mercury intrusion method（MIM） and nuclear magnetic resonance（NMR） imaging. A capillary-bundle physical model with random-distribution pores（improved model, IM） was established according to the parameters, and dry-shrinkage strain values were calculated and verified. Results show that in all pore types, capillary pores, and gel pores have the greatest impacts on concrete shrinkage, especially for pores 2.5-50 and 50-100 nm in size. The median radii are 34.2, 31, and 34 nm for RC0, RC30, and RC100, respectively. Moreover, the internal micropore size distribution of RC0 differs from that of RC30 and RC100, and the pore descriptions of MIM and NMR are consistent both in theory and in practice. Compared with the traditional capillary-bundle model, the calculated results of IM have higher accuracy as demonstrated by experimental verifi cation.
文摘This paper presents the results of an experimental survey on the potential application of DARC （dry asphalt rubber concrete） in rail superstructure, within sub-ballast layers by measuring its damping and mechanical properties. Based on the environmental friendly point of view the DARC has the significant advantage as the backfill material of sub-ballast layer because the rubber comes from the waste tires of truck and its usage can results a significant recycling of non-biodegradable wastes. After a preliminary mix-design of several DARCs, with different rubber content that confirmed by using the Marshall test, the stiffness modulus and damping ratio both of a standard bituminous mixture and of dry asphalt rubber concrete with a rubber content equal to 1.5% were determined using the four points bending device. The experimental results were compared and a numerical analysis by means of a 2D lumped mass model was developed in order to evaluate the different performance within the rail superstructure in terms both of the deflection and of the pressure on sub-grade. Both the results on the mechanical and dissipative properties of the DARC and the mechanical behavior of the correlate rail superstructure encourage the authors to continue the research on the application of such material for sub-ballast layers.
