Hot mix asphalt is the cornerstone of road design serving the basis of road networks in the transportation infrastructure of a country.Traditional formulations of hot mix asphalt suffer from inherent limitations such ...Hot mix asphalt is the cornerstone of road design serving the basis of road networks in the transportation infrastructure of a country.Traditional formulations of hot mix asphalt suffer from inherent limitations such as susceptibility to rutting and cracking due to severity of temperature changes.Carbon nanomaterials(CNMs)feature superb properties such as mechanical strength,and thermal and electrical conductivity.Recently,adding CNMs into hot mix asphalt,as an alternative to conventional additives,proved to be effective in enhancing overall performance of asphalt concrete;for example,it enhances its Marshall stability,rutting resistance and low-temperature crack resistance leading to roads with high longevity and sustainability.In addition,CNMs can offer new functional properties into asphalt mixtures such as self-healing,and thermal and electrical conductivity.This review presents the recent advances in integrating CNMs,specifically graphene and carbon nanotubes(CNTs),into asphalt mixtures.Features of nanomaterials such as specific surface area,geometry,and their effect on the properties of hot mix asphalt are comprehensively discussed.The review also explores the processing and characterization methods for CNMs-modified asphalt binder and their impact on the mixture workability and rheological performance.Furthermore,the article elaborates the structure-property relations of CNMs-modified asphalt mixtures at the macroscale(mechanical properties),microscale(morphology and microstructure)and atomic scale(molecular dynamic simulations).Functional properties of CNMs-modified asphalt were also discussed.More importantly,the authors provided a roadmap and mathematical model to assess the economic feasibility and sustainability of incorporating CNMs into the asphalt industry.At the end,potential and research directions in adding CNMs into asphalt industry are outlined.展开更多
Reactive powder concrete(RPC)is a relatively new type of high-performance concrete,offering enhanced load-bearing capacity,mechanical strength,and durability.The enhanced microstructural density of RPC with the incorp...Reactive powder concrete(RPC)is a relatively new type of high-performance concrete,offering enhanced load-bearing capacity,mechanical strength,and durability.The enhanced microstructural density of RPC with the incorporation of reinforcing fibers significantly increases its resistance to durability challenges,particularly against external sulfate attack(ESA).However,conventional laboratory testing methods for evaluating the resistance of RPC to ESA are limited.Hence,a new performance-based approach was developed to evaluate the durability of RPC exposed to ESA.Expansion of nine RPC mixtures designed by Taguchi L9 orthogonal array method with four factors(steel fiber content,water-to-binder ratio(w/b),silica fume content,and sodium sulfate(Na_(2)SO_(4))concentration)at three different temperatures(20,40,and 60℃)was used to calculate the reaction rate constant based on the first order chemical reaction kinetics.This mathematical model was rearranged to determine the activation energy(E_(a)),minimal energy required to initiate the ESA reaction,of RPC mixtures that were used to evaluate the performance of RPC mixtures exposed to ESA.The threshold value of E_(a) was determined from the correlation between Na_(2)SO_(4) solution concentrations and the E_(a) values of RPC mixtures.It was concluded that the model-defined parameters provide valuable insights to characterize the ESA durability of RPC.展开更多
基金funded by Nazarbayev University,Kazakhstan,through Faculty Development Competitive Research Grant Program:Grant No.040225FD4725.
文摘Hot mix asphalt is the cornerstone of road design serving the basis of road networks in the transportation infrastructure of a country.Traditional formulations of hot mix asphalt suffer from inherent limitations such as susceptibility to rutting and cracking due to severity of temperature changes.Carbon nanomaterials(CNMs)feature superb properties such as mechanical strength,and thermal and electrical conductivity.Recently,adding CNMs into hot mix asphalt,as an alternative to conventional additives,proved to be effective in enhancing overall performance of asphalt concrete;for example,it enhances its Marshall stability,rutting resistance and low-temperature crack resistance leading to roads with high longevity and sustainability.In addition,CNMs can offer new functional properties into asphalt mixtures such as self-healing,and thermal and electrical conductivity.This review presents the recent advances in integrating CNMs,specifically graphene and carbon nanotubes(CNTs),into asphalt mixtures.Features of nanomaterials such as specific surface area,geometry,and their effect on the properties of hot mix asphalt are comprehensively discussed.The review also explores the processing and characterization methods for CNMs-modified asphalt binder and their impact on the mixture workability and rheological performance.Furthermore,the article elaborates the structure-property relations of CNMs-modified asphalt mixtures at the macroscale(mechanical properties),microscale(morphology and microstructure)and atomic scale(molecular dynamic simulations).Functional properties of CNMs-modified asphalt were also discussed.More importantly,the authors provided a roadmap and mathematical model to assess the economic feasibility and sustainability of incorporating CNMs into the asphalt industry.At the end,potential and research directions in adding CNMs into asphalt industry are outlined.
基金Nazarbayev University funded this research under Faculty Development Competitive Research No.201223FD8803。
文摘Reactive powder concrete(RPC)is a relatively new type of high-performance concrete,offering enhanced load-bearing capacity,mechanical strength,and durability.The enhanced microstructural density of RPC with the incorporation of reinforcing fibers significantly increases its resistance to durability challenges,particularly against external sulfate attack(ESA).However,conventional laboratory testing methods for evaluating the resistance of RPC to ESA are limited.Hence,a new performance-based approach was developed to evaluate the durability of RPC exposed to ESA.Expansion of nine RPC mixtures designed by Taguchi L9 orthogonal array method with four factors(steel fiber content,water-to-binder ratio(w/b),silica fume content,and sodium sulfate(Na_(2)SO_(4))concentration)at three different temperatures(20,40,and 60℃)was used to calculate the reaction rate constant based on the first order chemical reaction kinetics.This mathematical model was rearranged to determine the activation energy(E_(a)),minimal energy required to initiate the ESA reaction,of RPC mixtures that were used to evaluate the performance of RPC mixtures exposed to ESA.The threshold value of E_(a) was determined from the correlation between Na_(2)SO_(4) solution concentrations and the E_(a) values of RPC mixtures.It was concluded that the model-defined parameters provide valuable insights to characterize the ESA durability of RPC.
