The heavyweight ultra-high performance concrete(HUHPC)was prepared with barite sand partially replaced by titanium-rich heavy slag sand(THS)at replacement proportion of 0%,30%,50%,70%and 100%in this work.The results s...The heavyweight ultra-high performance concrete(HUHPC)was prepared with barite sand partially replaced by titanium-rich heavy slag sand(THS)at replacement proportion of 0%,30%,50%,70%and 100%in this work.The results show that THS incorporation can effectively improve the mechanical properties and reduce the volume shrinkage of HUHPC.The HUHPC with 50%THS replacement reaches an apparent density of 2890 kg/m^(3)(for fresh HUHPC),28 d compressive strength of 129 MPa,28 d flexural strength of 23 MPa,28 d flexural toughness of 28.4,56 d volume shrinkage of 359×10^(-4) and,as expected,excellent durability.Microstructural investigation demonstrates that the internal curing of pre-wetted THS promotes the hydration of the surrounding cement paste thereby strengthening the interfacial transition zone,resulting in the“hard shell”formation around aggregate to“protect”the aggregate.Additionally,the“pin structure”significantly improves the cement paste-aggregate interfacial connection.The combination of“hard shell protection”and“pin structure”remarkably improve the mechanical properties of HUHPC produced with porous THS aggregate.展开更多
In order to determine the theoretical minimum clamping pressure required in carton clamp handling of heavyweight corrugated package(HCP)such as large packages or unitized agricultural product packages,a numerical mode...In order to determine the theoretical minimum clamping pressure required in carton clamp handling of heavyweight corrugated package(HCP)such as large packages or unitized agricultural product packages,a numerical model of clamping pressure was developed.To develop the model,the dynamic load factor was measured at the handling test course which was designed on the basis of actual handling environment of the target HCP.Also,the static-frictional coefficients between the HCPs and between the HCP and a rubber contact pad of carton clamp arm were analyzed.The main factors in the developed numerical model of clamping pressure were the handling load weight and the effective contact area of the carton clamp arm.In addition,field tests were performed to validate the theoretical minimum clamping pressure calculated from the model.Averaged slip distance from the single package and two packages handling was estimated as a 3.2 mm through field test,and it is expected that the 3.2 mm slip distance will be acceptable for a safe operation in the handling environment.The suggested analytical approach with the numerical model can be a useful means for estimating the clamping pressure of the carton clamps used to handle the HCP.展开更多
基金Funded by National Natural Science Foundation of China(Nos.52008002,U2006224 and 51878003)Doctoral Scientific Research Startup Foundation of Anhui Jianzhu University(No.2019QDZ66)。
文摘The heavyweight ultra-high performance concrete(HUHPC)was prepared with barite sand partially replaced by titanium-rich heavy slag sand(THS)at replacement proportion of 0%,30%,50%,70%and 100%in this work.The results show that THS incorporation can effectively improve the mechanical properties and reduce the volume shrinkage of HUHPC.The HUHPC with 50%THS replacement reaches an apparent density of 2890 kg/m^(3)(for fresh HUHPC),28 d compressive strength of 129 MPa,28 d flexural strength of 23 MPa,28 d flexural toughness of 28.4,56 d volume shrinkage of 359×10^(-4) and,as expected,excellent durability.Microstructural investigation demonstrates that the internal curing of pre-wetted THS promotes the hydration of the surrounding cement paste thereby strengthening the interfacial transition zone,resulting in the“hard shell”formation around aggregate to“protect”the aggregate.Additionally,the“pin structure”significantly improves the cement paste-aggregate interfacial connection.The combination of“hard shell protection”and“pin structure”remarkably improve the mechanical properties of HUHPC produced with porous THS aggregate.
基金supported by the Financial Supporting Project of Long-term Overseas Dispatch of Pusan National University’s Tenure-track Faculty,2014.
文摘In order to determine the theoretical minimum clamping pressure required in carton clamp handling of heavyweight corrugated package(HCP)such as large packages or unitized agricultural product packages,a numerical model of clamping pressure was developed.To develop the model,the dynamic load factor was measured at the handling test course which was designed on the basis of actual handling environment of the target HCP.Also,the static-frictional coefficients between the HCPs and between the HCP and a rubber contact pad of carton clamp arm were analyzed.The main factors in the developed numerical model of clamping pressure were the handling load weight and the effective contact area of the carton clamp arm.In addition,field tests were performed to validate the theoretical minimum clamping pressure calculated from the model.Averaged slip distance from the single package and two packages handling was estimated as a 3.2 mm through field test,and it is expected that the 3.2 mm slip distance will be acceptable for a safe operation in the handling environment.The suggested analytical approach with the numerical model can be a useful means for estimating the clamping pressure of the carton clamps used to handle the HCP.
