Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix propo...Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix proportion design method for RHPC using 100 % CRA and natural sand. Five groups of RHPC mixes with five strength grades（40, 50, 60, 70 and 80 MPa） were produced using CRA with four quality classes, and their workability, 28 d compressive strengths and frost resistances（measured by the compressive strength loss ratio and the relative dynamic modulus of elasticity） were tested. Relationships between the 28 d compressive strength, the frost resistance and the CRA quality characteristic parameter, water absorption, were then developed. The criterion of a CRA maximum water absorption limit value for RHPC was suggested, independent of its source and quality class. The results show that all RHPC mixes achieve the expected target workability, strength, and frost durability. The research results demonstrate that the application of the proposed method does not require trial testing prior to use.展开更多
To explore mix proportion design of RAC with aggregates tightly packed,the dry and wet packing density of recycled coarse aggregates mixture system and recycled coarse and fine aggregates were tested,then the influenc...To explore mix proportion design of RAC with aggregates tightly packed,the dry and wet packing density of recycled coarse aggregates mixture system and recycled coarse and fine aggregates were tested,then the influence of replacement rate and particle size ratio on the packing density of particle system was explored,the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed,and the mix proportion optimization for recycled aggregate concrete with dry-wet packing model was carried out.The experimental results show that,with the increasing of recycled aggregate replacement rate or fine-grained volume ratio,the dry packing density of recycled coarse aggregates decreases gradually.With the increasing of replacement rate,the particle gradation can be optimized by increasing coarsegrained volume ratio.There is a significant effect for particle morphology parameter K and the particle size ratio on the packing density of the binary mixed system,and the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed.The maximum increase in compressive strength and tensile strength of RAC with mix proportion optimized by the dry-wet packing model are 12.94%and 11.09%,and the cementitious materials is reduced by 21.83%,then the superiority of the mix proportion optimization of RAC with the dry-wet close packing model is confirmed.The results of this paper can provide a theoretical basis for the mix proportion design of RAC.展开更多
With the resource shortage in coastal areas,the construction of concrete structures using freshwater and river sand has brought great economic and environmental costs.The use of seawater,sea sand,and coral aggregates ...With the resource shortage in coastal areas,the construction of concrete structures using freshwater and river sand has brought great economic and environmental costs.The use of seawater,sea sand,and coral aggregates in concrete mixes has become an alternative solution for coastal and marine structures,especially for offshore structures and artificial islands.In this study,378 seawater,sea sand,and coral aggregate concrete(Coral-SWSSC)specimens were prepared,and their mechanical properties were investigated comprehensively through compressive tests to explore the optimized mix design at different grades.Results showed that the mechanical properties of Coral-SWSSC were strongly correlated with the water-to-binder ratios,coastal particle gradings,and pretreatment method of coastal particles.Based on the experimental results,mix proportion designs of CoralSWSSC were proposed for concrete from C20 to C50 grades,and the failure mechanism of Coral-SWSSC at different grades was discussed according to their respective failure modes.The findings of the current study provide knowledge on the optimized design of Coral-SWSSC,which can be used to promote the application of Coral-SWSSC in offshore,marine,and ocean engineering.展开更多
ARHM asphalt rubber has been applied in pavement engineering research for more than 20 years in our country. It has been applied and popularized in Beijing-Qinhuangdao Expressway, Jinshi Expressway and other projects ...ARHM asphalt rubber has been applied in pavement engineering research for more than 20 years in our country. It has been applied and popularized in Beijing-Qinhuangdao Expressway, Jinshi Expressway and other projects successively, but its content is relatively low. According to the characteristics that rubber powder can greatly improve the durability of asphalt concrete, the research on the mix proportion of high content (30%) rubber powder asphalt concrete was carried out. It has been verified that it has significantly improved the dynamic stability, low-temperature bending, freeze-thaw splitting and water seepage performance, and has been put into use in the bid section ZT2 of Jingde Expressway, meeting the use requirements of "no minor repair for 15 years and no major repair for 40 years" for the permanent pavement of Jingde Expressway.展开更多
基金Funded by the National Natural Science Foundation of China(No.51278073)Prospective Joint Research Project of Jiangsu Province(No.BY2015027-23)State Key Laboratory for Geo Mechanics and Deep Underground Engineering,China University of Mining&Technology(No.SKLGDUEK1704)
文摘Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix proportion design method for RHPC using 100 % CRA and natural sand. Five groups of RHPC mixes with five strength grades（40, 50, 60, 70 and 80 MPa） were produced using CRA with four quality classes, and their workability, 28 d compressive strengths and frost resistances（measured by the compressive strength loss ratio and the relative dynamic modulus of elasticity） were tested. Relationships between the 28 d compressive strength, the frost resistance and the CRA quality characteristic parameter, water absorption, were then developed. The criterion of a CRA maximum water absorption limit value for RHPC was suggested, independent of its source and quality class. The results show that all RHPC mixes achieve the expected target workability, strength, and frost durability. The research results demonstrate that the application of the proposed method does not require trial testing prior to use.
基金Funded by joint Funds of the National Natural Science Foundation of China(No.U1904188)the Key Research Project of Henan Province for Colleges and Universities(No.26A560009)+3 种基金the Jiaozuo City Science and Technology Planning Project(No.2025210099)the Henan Provincial Science and Technology Research Project(No.252102320305)the Natural Science Foundation of Henan Province(No.252300421917)the Project by Key Laboratory of Intelligent Construction and Safety Operation and Maintenance of Underground Engineering in Henan Province(No.KFKT2024-01)。
文摘To explore mix proportion design of RAC with aggregates tightly packed,the dry and wet packing density of recycled coarse aggregates mixture system and recycled coarse and fine aggregates were tested,then the influence of replacement rate and particle size ratio on the packing density of particle system was explored,the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed,and the mix proportion optimization for recycled aggregate concrete with dry-wet packing model was carried out.The experimental results show that,with the increasing of recycled aggregate replacement rate or fine-grained volume ratio,the dry packing density of recycled coarse aggregates decreases gradually.With the increasing of replacement rate,the particle gradation can be optimized by increasing coarsegrained volume ratio.There is a significant effect for particle morphology parameter K and the particle size ratio on the packing density of the binary mixed system,and the packing density prediction model of recycled coarse aggregates based on particle morphology was constructed.The maximum increase in compressive strength and tensile strength of RAC with mix proportion optimized by the dry-wet packing model are 12.94%and 11.09%,and the cementitious materials is reduced by 21.83%,then the superiority of the mix proportion optimization of RAC with the dry-wet close packing model is confirmed.The results of this paper can provide a theoretical basis for the mix proportion design of RAC.
基金supported by the National Natural Science Foundation of China (Grant Nos.52078310,51878420)the Ministry of Science and Technology of China (Grant Nos.2018YFC1504303,2017YFC1503103)Xingliao Talent Program of Liaoning Province (Grant No.XLYC1902038)。
文摘With the resource shortage in coastal areas,the construction of concrete structures using freshwater and river sand has brought great economic and environmental costs.The use of seawater,sea sand,and coral aggregates in concrete mixes has become an alternative solution for coastal and marine structures,especially for offshore structures and artificial islands.In this study,378 seawater,sea sand,and coral aggregate concrete(Coral-SWSSC)specimens were prepared,and their mechanical properties were investigated comprehensively through compressive tests to explore the optimized mix design at different grades.Results showed that the mechanical properties of Coral-SWSSC were strongly correlated with the water-to-binder ratios,coastal particle gradings,and pretreatment method of coastal particles.Based on the experimental results,mix proportion designs of CoralSWSSC were proposed for concrete from C20 to C50 grades,and the failure mechanism of Coral-SWSSC at different grades was discussed according to their respective failure modes.The findings of the current study provide knowledge on the optimized design of Coral-SWSSC,which can be used to promote the application of Coral-SWSSC in offshore,marine,and ocean engineering.
文摘ARHM asphalt rubber has been applied in pavement engineering research for more than 20 years in our country. It has been applied and popularized in Beijing-Qinhuangdao Expressway, Jinshi Expressway and other projects successively, but its content is relatively low. According to the characteristics that rubber powder can greatly improve the durability of asphalt concrete, the research on the mix proportion of high content (30%) rubber powder asphalt concrete was carried out. It has been verified that it has significantly improved the dynamic stability, low-temperature bending, freeze-thaw splitting and water seepage performance, and has been put into use in the bid section ZT2 of Jingde Expressway, meeting the use requirements of "no minor repair for 15 years and no major repair for 40 years" for the permanent pavement of Jingde Expressway.
