Robotic-based technologies such as automated spraying or extrusion-based 3-dimensional(3D)concrete printing can be used to build tunnel linings,aiming at reducing labor and mitigating the associated safety issues,espe...Robotic-based technologies such as automated spraying or extrusion-based 3-dimensional(3D)concrete printing can be used to build tunnel linings,aiming at reducing labor and mitigating the associated safety issues,especially in the high-geothermal environment.Extrusion-based 3D concrete printing(3DCP)has additional advantages over automated sprayings,such as improved surface quality and no rebound.However,the effect of different temperatures on the adhesion performance of 3D-printed materials for tunnel linings has not been investigated.This study developed several alkali-activated slag mixtures with different activator modulus ratios to avoid the excessive use of Portland cement and enhance sustainability of 3D printable materials.The thermal responses of the mixtures at different temperatures of 20 and 40℃ were studied.The adhesion strength of the alkali-activated material was evaluated for both early and later ages.Furthermore,the structural evolution of the material exposed to different temperatures was measured.This was followed by microstructure characterization.Results indicate that elevated temperatures accelerate material reactions,resulting in improved early-age adhesion performance.Moreover,higher temperatures contribute to the development of a denser microstructure and enhanced mechanical strength in the hardened stage,particularly in mixtures with higher silicate content.展开更多
Three-dimensional concrete printing(3DCP)is increasingly being applied in harsh environments and isolated regions.However,the effective utilization of aeolian sand(AS)resources and by-products derived from arid zones ...Three-dimensional concrete printing(3DCP)is increasingly being applied in harsh environments and isolated regions.However,the effective utilization of aeolian sand(AS)resources and by-products derived from arid zones for 3DCP is yet to be fully realized.This study developed a three-dimensional(3D)printing composite using AS and magnesium oxychloride cement(MOC)from local materials.The effects of the mole ratio of MgO/MgCl_(2)and sand/binder(S/B)ratio on the mechanical properties such as water resistance,drying shrinkage strain,rheology,and printability,were investigated systematically.The results indicated that the optimal mole ratio of MgO/MgCl_(2),was 8,which yielded the desired mechanical performance and water resistance.Furthermore,the S/B ratio can be increased to three within the desired printability to increase the AS utilization rate.The rheological recovery and buildability of the 3D-printed MOC with AS were verified.These findings provide a promising strategy for construction in remote deserts.展开更多
基金the Industrial Research Fund(No.IOF.PRO.2022.0010.01).
文摘Robotic-based technologies such as automated spraying or extrusion-based 3-dimensional(3D)concrete printing can be used to build tunnel linings,aiming at reducing labor and mitigating the associated safety issues,especially in the high-geothermal environment.Extrusion-based 3D concrete printing(3DCP)has additional advantages over automated sprayings,such as improved surface quality and no rebound.However,the effect of different temperatures on the adhesion performance of 3D-printed materials for tunnel linings has not been investigated.This study developed several alkali-activated slag mixtures with different activator modulus ratios to avoid the excessive use of Portland cement and enhance sustainability of 3D printable materials.The thermal responses of the mixtures at different temperatures of 20 and 40℃ were studied.The adhesion strength of the alkali-activated material was evaluated for both early and later ages.Furthermore,the structural evolution of the material exposed to different temperatures was measured.This was followed by microstructure characterization.Results indicate that elevated temperatures accelerate material reactions,resulting in improved early-age adhesion performance.Moreover,higher temperatures contribute to the development of a denser microstructure and enhanced mechanical strength in the hardened stage,particularly in mixtures with higher silicate content.
基金the National Natural Science Foundation of China(Grant Nos.52178198,52208239,and U20A20313)the Natural Science Foundation of Hebei(Nos.E2022202203,E2021202039,and E2022202041)the Natural Science Foundation of Tianjin(Nos.20JCYBJC00710 and 22JCQNJC00240).
文摘Three-dimensional concrete printing(3DCP)is increasingly being applied in harsh environments and isolated regions.However,the effective utilization of aeolian sand(AS)resources and by-products derived from arid zones for 3DCP is yet to be fully realized.This study developed a three-dimensional(3D)printing composite using AS and magnesium oxychloride cement(MOC)from local materials.The effects of the mole ratio of MgO/MgCl_(2)and sand/binder(S/B)ratio on the mechanical properties such as water resistance,drying shrinkage strain,rheology,and printability,were investigated systematically.The results indicated that the optimal mole ratio of MgO/MgCl_(2),was 8,which yielded the desired mechanical performance and water resistance.Furthermore,the S/B ratio can be increased to three within the desired printability to increase the AS utilization rate.The rheological recovery and buildability of the 3D-printed MOC with AS were verified.These findings provide a promising strategy for construction in remote deserts.
