Rutting is one of the most damages in the asphalt surfaces for the orthotropic steel bridge decks. With Hamburg wheel tracking device, the suitable test conditions for Gussasphalt in Germany are pointed out, the high ...Rutting is one of the most damages in the asphalt surfaces for the orthotropic steel bridge decks. With Hamburg wheel tracking device, the suitable test conditions for Gussasphalt in Germany are pointed out, the high temperature behaviour of Gussasphalt with different binders are tested and compared. The polymer modified binder has higher resistance stability to rutting. The retained time and mixed frequency have obvious effects on Gussasphalt behaviour during Gussasphalt retained period.展开更多
The paper presents examples of technological designs for concrete placement in road bridges constructed during the S5/S 10 expressway extension in Poland. The project included eight concrete or composite bridge struct...The paper presents examples of technological designs for concrete placement in road bridges constructed during the S5/S 10 expressway extension in Poland. The project included eight concrete or composite bridge structures with different numbers of decks. The concrete placement technology is presented for the following bridge decks： slabs cast-in-situ, composite with precast or VFT （prefabricated composite beam） beams and mixed with cast in situ slabs and VFT-WIB （filler beam） beams. Continuous concrete placement was adopted for almost all the bridge superstructures except the mixed-type decks where construction joints were necessary. To control shrinkage, formwork deformations and existing restraints, the concrete was poured in layers and in stages. The design pace of concrete placement was moderate to be regulated at site without compromising safety and quality. The placement methods enabled both efficient and safe concrete pours.展开更多
Mesoporous LaMnO3 perovskite catalysts with high surface area were synthesized by using the recently developed hard templating method designated as ＂nanocasting＂.Ordered mesoporous silica designated as SBA-15 was us...Mesoporous LaMnO3 perovskite catalysts with high surface area were synthesized by using the recently developed hard templating method designated as ＂nanocasting＂.Ordered mesoporous silica designated as SBA-15 was used as the hard template.It was found that the surface area of the nanocast perovskites can be tuned（80–190 m2/g）by varying the aging temperature of the SBA-15 template.Nanocast LaMnO3 catalysts showed high conversion efficiencies for the total oxidation of methanol under steady state conditions,the one with the highest value of surface area being the best catalysts,as expected.Kinetic studies were performed for all of the synthesized catalysts.Rate constants were found to vary in accordance with the specific surface area of the nanocast catalyst which depends on the aging temperature of the parent template.From the rate constants obtained from experimental conversions at various space velocities（19500 to 78200 h〈sup〉–1）,values of activation energy and pre-exponential factor for the three nanocast LaMnO3 catalysts were determined by the linear regression of the Arrhenius plot.It is observed that the activation energy for all the catalysts remain constant irrespective of the variation in specific surface area.Further,a linear relationship was found to exist between the pre-exponential factor and specific surface areas of the catalysts indicating that the rates per unit surface area remains the same for all the catalysts.展开更多
This paper discusses the technique of casting concrete ofmicropiles with pressures and the consequence of comparisons with normal way of casting concrete （casting with gravity）. Preliminary geotechnical studies have...This paper discusses the technique of casting concrete ofmicropiles with pressures and the consequence of comparisons with normal way of casting concrete （casting with gravity）. Preliminary geotechnical studies have been made in specific area in Sudan to predict the soil parameters and then an experimental work has been done for an estimated number ofmicropiles with different diameters and different techniques of placing concrete with various amount of pressure. This study was carried out to learn the usefulness of this technique in the field of structural foundations in Sudan. Capacities of micropiles were compared in cases of non-pressure casting （normal way of casting concrete） and pressure casting. Through the results, it was found that the entry of pressure factor in the operation of casting concrete increases the capacities of micropiles. The increased value of ultimate load depends on the amount of pressure applied.展开更多
文摘Rutting is one of the most damages in the asphalt surfaces for the orthotropic steel bridge decks. With Hamburg wheel tracking device, the suitable test conditions for Gussasphalt in Germany are pointed out, the high temperature behaviour of Gussasphalt with different binders are tested and compared. The polymer modified binder has higher resistance stability to rutting. The retained time and mixed frequency have obvious effects on Gussasphalt behaviour during Gussasphalt retained period.
文摘The paper presents examples of technological designs for concrete placement in road bridges constructed during the S5/S 10 expressway extension in Poland. The project included eight concrete or composite bridge structures with different numbers of decks. The concrete placement technology is presented for the following bridge decks： slabs cast-in-situ, composite with precast or VFT （prefabricated composite beam） beams and mixed with cast in situ slabs and VFT-WIB （filler beam） beams. Continuous concrete placement was adopted for almost all the bridge superstructures except the mixed-type decks where construction joints were necessary. To control shrinkage, formwork deformations and existing restraints, the concrete was poured in layers and in stages. The design pace of concrete placement was moderate to be regulated at site without compromising safety and quality. The placement methods enabled both efficient and safe concrete pours.
基金supported by the the National Science and Engineering Research Council(Canada)the Fonds Québécois de la Recherche sur la Nature et les Technologies(Province of Quebec)
文摘Mesoporous LaMnO3 perovskite catalysts with high surface area were synthesized by using the recently developed hard templating method designated as ＂nanocasting＂.Ordered mesoporous silica designated as SBA-15 was used as the hard template.It was found that the surface area of the nanocast perovskites can be tuned（80–190 m2/g）by varying the aging temperature of the SBA-15 template.Nanocast LaMnO3 catalysts showed high conversion efficiencies for the total oxidation of methanol under steady state conditions,the one with the highest value of surface area being the best catalysts,as expected.Kinetic studies were performed for all of the synthesized catalysts.Rate constants were found to vary in accordance with the specific surface area of the nanocast catalyst which depends on the aging temperature of the parent template.From the rate constants obtained from experimental conversions at various space velocities（19500 to 78200 h〈sup〉–1）,values of activation energy and pre-exponential factor for the three nanocast LaMnO3 catalysts were determined by the linear regression of the Arrhenius plot.It is observed that the activation energy for all the catalysts remain constant irrespective of the variation in specific surface area.Further,a linear relationship was found to exist between the pre-exponential factor and specific surface areas of the catalysts indicating that the rates per unit surface area remains the same for all the catalysts.
文摘This paper discusses the technique of casting concrete ofmicropiles with pressures and the consequence of comparisons with normal way of casting concrete （casting with gravity）. Preliminary geotechnical studies have been made in specific area in Sudan to predict the soil parameters and then an experimental work has been done for an estimated number ofmicropiles with different diameters and different techniques of placing concrete with various amount of pressure. This study was carried out to learn the usefulness of this technique in the field of structural foundations in Sudan. Capacities of micropiles were compared in cases of non-pressure casting （normal way of casting concrete） and pressure casting. Through the results, it was found that the entry of pressure factor in the operation of casting concrete increases the capacities of micropiles. The increased value of ultimate load depends on the amount of pressure applied.
