Abstract:In order to reveal the crack-resisting performance of the steel-Ultra-High Performance Concrete （UHPC）lightweight composite deck structure subjected to traffic disturbance during construction, theoretical and ex? perimental studies based on the Chongqing Yuzui Yangtze River Bridge are presented in this paper. Firstly, the maxi? mum tensile strain of the UHPC layer’s top surface caused by traffic during construction (referred to as disturbance amplitude hereinafter) was obtained through finite element analyses, and the results showed that: during construction,the maximum longitudinal and transverse disturbance amplitudes of the UHPC layer of this bridge were 144 με and 60 με, respectively. Secondly, 6 model specimens were designed and manufactured with reference to the actual struc? ture. Then, the specimens were divided into two groups, each group included one undisturbed control specimen and two disturbed specimens, which were subjected to simulated traffic disturbance during the setting of UHPC. The de? signed amplitudes of these two groups were 160 με and 240 με, respectively. Finally, the crack-resistance perfor? mance of the control specimens and the disturbed specimens were compared through 4-point negative moment static tests. The experimental results showed that the disturbance did not substantially affect the crack-resisting perfor? mance of the specimens when its amplitude was less than 160 με. On the contrary, the disturbance aroused damages to the UHPC layer when its amplitude was over 160 με, resulting in a decrease in the nominal cracking stresses of the disturbed specimens. Therefore, it is suggested that the limit of traffic disturbance amplitude during construction should be set to 160 με.

Abstract:For UHPC-SMA composite specimens, two types of tack coat materials, i.e., hot-melt modified epoxy resin 202 and high-elastic and high-viscosity asphalt PG100, were chosen, and monotonic tests and cyclic tests were carried out. The similarities, differences, and associations were investigated of different interlayer failure modes (shear and tensile). The possible link between various parameters obtained from a monotonic shear test and the shear fatigue life were examined. The results show that the temperature has a significant effect on the interlayer bond perfor? mances. With the increase of test temperature, the pull-off strength and interlayer shearing strength (ISS) decreases greatly, and fatigue life between UHPC and SMA also decreases significantly. Pull-off strength, interlayer shearing strength, shear stiffness (IS), interlayer bonding energy (IBE), and fatigue life of 202 are significantly better than those of PG100, as well as its stability in high temperatures. The pull-off strength has a great linear correlation with ISS, with R2 equaling 0.936, indicating that the pull-off test is a reasonable and reliable method for preliminary evaluating the bond performances between UHPC and SMA. The parameters obtained from the monotonic shear test are closely related to the shear fatigue life. The higher the monotonic parameters, the longer the fatigue life is. The correlations are ranked as: IBE > ISS > IS and R2 are 0.984, 0.945, and 0.779, respectively. IBE accounts for not only the shear force in the interlayer but also the resulting shear deformation resistance of the tack coat, which repre? sents the amount of energy dissipated during interlayer resisting shearing. It can be used as a reliable index to evalu? ate the interlayer bonding performances and to further predict the shearing fatigue life between UHPC and SMA.

Abstract:Prestressed UHPC strengthening technology was proposed to achieve a more efficient and durable strengthening for damaged RC structures. In order to investigate the effect of prestressed UHPC strengthening tech? nology on flexural behavior of RC beams, normal section bending tests were carried out on two damaged RC strength? ened beams (Reinforced-UHPC Strengthened Beam，RUB and Prestressed-UHPC Strengthened Beam，PUB) and one unstrengthened contrast RC beam (Reinforced Concrete Beam，RCB). Among strengthened beams, RUB was strengthened by the reinforced UHPC layer, and PUB was strengthened by the prestressed UHPC layer. The experi? mental results showed that all test beams showed conventional bending failure, and the flexural behavior of RC beams was significantly improved after being strengthened. The flexural strengthening efficiency of the prestressed UHPC layer was higher than that of the reinforced UHPC layer. The prestressed UHPC layer improved the stress state of the structure and further inhibited the formation and development of cracks. In addition, the better tensile performance of the prestressed UHPC layer made the flexural stiffness and ultimate bearing capacity of RC beams further improved. Compared with RUB, the cracking load and ultimate bearing capacity of PUB were increased by 89.2% and 36.9%,respectively. Also, a calculation formula of ultimate bearing capacity of prestressed UHPC strengthened beam was proposed, and the calculation results were in good agreement with the experimental results.

Abstract:The Anhai’ao Bridge located in Pingtan, Fujian is a three-span extradosed cable-stayed bridge with a main span of 150 m. For the first time, its design scheme adopted a fan-shape composite bridge tower composed of five CFST arched tower columns and curved steel pipes. In order to study the spatial force transmission mechanism of this new type of extradosed cable-stayed bridge, a 1∶25 large-scale model was fabricated and a static loading test was performed. Combined with the finite element analysis results of the actual bridge, the loading state of the specialshaped main tower, main girder, and inhaul cable under different individual loads was discussed. The research re? sults show that under the action of vehicle load, the CFST fan-shaped composite tower bears about 10% of the load through the inhaul cable, i.e., the live load distribution ratio between the main tower and the main girder was main? tained at 1∶9. Compared with the continuous girder bridge, the maximum strain and mid-span deflection of the main girder of the extradosed cable-stayed bridge can be reduced by about 10%. As the load level increased to 2.0 times the equivalent lane load, the deflection and strain of the main girder, the force increase of the inhaul cables, and the strain of each tower column of the main tower presented basically the same linearly changing trends. Under the action of vehicle load or foundation settlement, the middle tower column and the secondary tower column of the fan-shaped composite tower bore most of the load transmitted by the inhaul cables and their stress levels were relatively high, and the side tower column supported small force; the load distribution ratio of the middle tower column, the second? ary tower column, and the side tower column was about 10∶10∶1; the steel tube at the junction of the curve section and the straight section and the bottom section of the tower column were the most unfavorable. Moreover, compared with the effects of vehicle load and foundation settlement, the CFST fan-shaped composite tower was more sensitive to the temperature effect, the overall stress levels of each tower column were equivalent, and the top section of the tower column had the highest stress. The above research results can provide references for subsequent research and design of similar structures.

Abstract:In order to study the material mechanical properties and constitutive relationship of domestic austen? itic S30408 stainless steel bridge deck sandwich panel, uniaxial tensile tests of various stainless steel specimens were carried out at room temperature. Considering several parameters including the thickness, orientation, and hot air heat? ing and cooling treatment of specimens, a total of 12 groups of 60 tensile specimens were designed. The nominal stress-strain curve and parameters such as initial elastic modulus, yield strength, tensile strength, and strain hardening index of stainless steel specimens were obtained，the influence degree of thickness and orientation on mechanical properties of stainless steel specimens were revealed, and the nominal stress-strain test curves of the specimens were compared with the classical constitutive models. The results show that stainless steel has obvious nonlinearity and an? isotropy; the microscopic morphology is analyzed by SEM, and it is determined that the fracture of stainless steel be? longed to ductile fracture; 8 mm S type specimens have better plasticity than 6 mm S type specimens for the stainless steel, and the plasticity of 8 mm Q type specimens are worse than that of 6 mm Q type specimens; the elongation and shrinkage of specimens in the rolling direction of sandwich panel are higher than those in the vertical rolling direc? tion and the oblique 45°;the mechanical properties of stainless steel are obviously changed after high-temperature treatment in hot air brazing furnace, the yield strength and tensile strength are lower than those of stainless steel, and the plasticity is worse,but the initial modulus of elasticity is almost constant；when ε < ε0.2，each constitutive models fit well with the test curves,but when ε ≥ ε0.2，R-O model has a large deviation. Rasmussen model has the best fit? ting effect and can be applied to the design and research of stainless steel sandwich panel structures.

Abstract:：To study the vortex-induced force model of the steel box girder with projecting slabs, a cable-stayed bridge with a main span of 160 m was taken as the engineering background in this paper. First, a numerical simula? tion method with two-way fluid-structure interaction was used to analyze the whole process of vortex-induced vibra? tion of a steel box girder with projecting slabs. The vibration amplitudes of the main girder section were calculated under different wind speeds, and they were compared with those of wind tunnel tests. Then, the time-history of vortexinduced force of the main girder was extracted based on the validated numerical simulation results. A mathematical model of the vortex-induced force for the steel box girder with projecting slabs was established according to the re? sidual values between the reconstituted and target vortex-induced forces. Finally, the vortex-induced response of the main girder was inversely solved by using the fourth-order Runge-Kutta method to further verify the accuracy of the proposed vortex-induced force model, and on this basis, the steady amplitude expression of vortex-induced vibration of the main girder was deduced. The results show that the lock-in range and the amplitudes of the vortex-induced vi? bration for the main girder obtained from the numerical simulations agree well with those obtained from the wind tun? nel tests, and the maximum amplitude occurs at the oncoming wind speed of 7.2 m/s; in addition to the most impor? tant fundamental-frequency component, there are also double- and triple-frequency components when conducting the spectrum analysis on the time-history of vortex-induced force of the main girder, which implies that the vortexinduced force of the main girder exhibits certain nonlinear characteristics; according to the proposed expression for the steady amplitude of vortex-induced vibration of the main girder, it is found that the steady amplitude decreases with the increasing absolute value of parameter P12, but it increases with the increase of the parameter P10.

Abstract:Due to the excellent mechanical and economic performances of the Π-shaped steel-concrete compos? ite girder, it is widely used in long-span cable-stayed bridges. However, the aerodynamics performance of the girder is relatively poor, and the vortex-induced vibration (VIV) of the girder is prone to occur for the improper aerodynamic design, which affects driving comfort and safety, or structural fatigue. Based on Chao-Shan Bridge in Guangdong, a single-pylon cable-stayed bridge with a main span of 205 m and Π-shaped steel-concrete composite deck, the in? vestigations on the VIV and aerodynamic countermeasures of the Π-shaped steel-concrete composite deck were con? ducted. Firstly, the VIV of the original girder section in-service state was studied by applying wind tunnel tests of the rigid segment model with a length scale of 1∶50. Then, the effects of aerodynamic countermeasures on the VIV of the Π-shaped steel-concrete composite girder, such as the lower stability plate, the deflectors, the skirt plates, and the upper central stability plate were studied, respectively. Finally, the computational fluid dynamics (CFD) method was adopted to study the control mechanism of the aerodynamic countermeasures. The results show that there is a large vortex vibration of the original girder section within the design wind speed, and the peak value of the VIV exceeds the limit value of the specification. The VIV of the girder can be controlled remarkably with the combined countermea? sures of three lower stability plates, vertical skirt plates on both sides of the girder, and an upper central stability plate. The control mechanism of the combined countermeasures on the VIV of the Π-shaped steel-concrete compos? ite deck is mainly as follow: the three lower stability plates can effectively destroy the large vortexes on the lower side of the girder; the vertical skirt plates set on both sides of the girder can improve the aerodynamic streamline of the girder and the upper central stability plate can effectively prevent the movement of the larger vortexes on the top side of the girder.

Abstract:In order to study the bond anchorage properties of steel bars after yielding, the strain distribution of steel bars was measured by the method of slotted steel bar surface and embedded resistance strain gauge. A total of 15 beam end bond anchorage tests were carried out by taking the strength grade of steel bars, the strength of concrete, the diameter of steel bars, the thickness of the protective layer, the ratio of the hoop, and the anchorage length as vari? ables. The test results show that the relative slip of the loading end increases significantly after steel bar yield, the bond stress of the yielding section decreases significantly, and the maximum yield penetration depth is related to the constraint of the steel bar and the diameter of the steel bar. Based on the test results, the formula for calculating the relative slip of the loading end after yielding is obtained by statistical regression. At the same time, a calculation method of the anchorage length after steel bar yielding is proposed, which can effectively calculate the anchorage length after steel bar yielding.

Abstract:In order to study the influence of the corrosion of steel bars on the connection performance of grouting sleeve joints, a pull-out test was carried out on 20 specimens subjected to artificial corrosion. The test obtained the failure modes of the steel bars of different diameters in the grouting sleeves under different corrosion rates, the strain of the anchoring internal steel bars vs the load slip curves. The bond stress distribution curves, relative slip curves, and bond-slip curves at different anchorage positions with different diameter steel bars under different corrosion rates are compared and analyzed. Through the test results and theoretical analysis, it is found that as the corrosion rate increases, the pull-out ability of the steel bars is attenuated to varying degrees. When the corrosion rate reaches 12%, the pull-out ability of the steel bars in the grouting sleeve is reduced by about 50%. The bond stress attenua? tion mechanism of corroded steel bars in the grouting sleeve is obtained. A function model of the bonding and anchoring position of the steel bars before and after corrosion is established, and the parameter values are determined. The bond-slip constitutive relationship between the steel bars before and after corrosion and the grouting material is es? tablished considering the bond and anchor position function, which provides a reference for the finite element analy? sis of steel bars and the grouting material before and after corrosion.

Abstract:In order to improve the efficiency and accuracy of corroded cracks detection and classification in rein? forced concrete, a corroded cracks identification model Steel Corrosion Net (SCNet) based on deep learning Convolu? tional Neural Network (CNN) is proposed. A data set of 39 000 crack figures is firstly built by original data collection and data enhancement, a SCNet three-classification neural network model is then built and tested by TensorFlow learning framework and Python. According to the training and testing accuracies of the model, the structure and pa? rameters of the SCNet network model are optimized and the result of the SCNet is compared with two traditional test? ing methods. The result shows that the SCNet model established in this paper achieves the classification accuracy of 96.8%, which means the SCNet model can effectively identify and classify the corroded cracks in reinforced concrete with high accuracy and measurability. Under the conditions of noise interference such as shadows and distortions, those two traditional testing methods fail to ideally classify, whereas the SCNet model shows a relatively stable classification performance.

Abstract:In order to study the effect of joint structure on the mechanical performance of densely assembled pre? stressed reinforced concrete composite slabs, an enhanced tight joint details is proposed, and the flexural tests of three groups of composite plates were designed. The test systematically studied the bearing capacity, stiffness, failure mode, crack and deformation performance of each group of specimens, and the joint force transmission performance of the jointed laminated slab as well as the two-way mechanical characteristics of the prestressed composite floor are analyzed. The test results show that the enhanced tight joint can improve the flexural stiffness of the composite slab in the vertical direction of the joint, its bearing capacity is close to that of the cast-in-place slab, and it can ensure the effective load transmission at the joint. The crack morphology at the joint position is good when the joint plate speci? men fails, and no tear damage occurs along the composite surface. The bearing capacity and deformation performance of the prestressed composite slabs are good. The mechanical performance test of the prestressed composite floor fur? ther shows that the composite slab with the reinforced joint structure can carry out two-way load transmission. An ul? timate bearing capacity formula of the prestressed composite floor was established based on the principle of virtual work. The calculated value of the ultimate load is good in agreement with the experimental value, which verifies the rationality of the assumed plastic hinge line mode. The strip method was used to verify the two-way mechanical per? formance of the prestressed composite floor.

Abstract:Aiming at the scale model design and similarity prediction of the buckling of the new typical gas holder’s body (large thin-walled ring and stringer stiffened-cylindrical shell) under axial compression, general similitude requirements and scaling laws of stiffened shells under axial compression are presented based on the dis? crete stiffened method and the total energy of the structural system. For the ring and stringer stiffened-cylindrical shells with different initial imperfections and modeling material properties, the partial similitude of the post-buckling behaviors under axial compression is mainly investigated. The results show that: using partial similitude scaling laws for the post-buckling of stiffened cylindrical shells under axial compression, scaled models can accurately predict the post-buckling behaviors of prototypes of discretely ring and stringer stiffened-cylindrical shells under axial com? pression. When the material Poisson's ratio of the model and the prototype is the same, the model can accurately pre? dict the post-buckling behaviors of the prototype under axial compression. As the material Poisson’s ratio deviation between the model and the prototype increases, the deviation of the post-buckling behaviors between the predicted prototype and its corresponding prototype gradually increases. In conclusion, the design method of scale models and scale laws are suitable for the similarity prediction of the post-buckling behaviors of discretely ring and stringer stiffened-cylindrical shells with different initial imperfections and material properties, which provides a reference for the scale model design and test of similar structures in practical engineering.

Abstract:Quasi-static experiments were conducted to study the failure mode and bearing mechanism of exter? nal ALC wall panel and traditional hook blot connections. In view of the insufficiency of the above connections, the seismic detail measures of placing the densified steel mesh around the internal connections in ALC wall panels were proposed , and the mechanical performance of the connections is studied. For this purpose, wall panels with and with? out an opening and the panel reinforced with steel mesh were designed, and low-cycle loading tests were conducted on these specimens. The finite element software ABAQUS was used to conduct numerical simulation. The results showed that openings were the weak components of ALC panels and destroyed firstly, but the size of openings has little effect on steel frame’s seismic performance. For the specimens with traditional hook blot connections, when the story drift ratio was less than 1/250 rad, there were vertical cracks on filling materials between ALC panels and tiny horizontal cracks around blot connections, which satisfies the requirements of the serviceability limit state. When the story drift ratio reached 1/75 rad，the cracks around connections develop obliquely, and the surrounding concrete was gradually compressed and crushed, so the panels were less likely to adapt to the deformation of main structures with the risk of dropping down and collapse under rare earthquake. However, this measure for the specimens embedded with reinforcing steel mesh in the panel was effective and reasonable, which provide enough force support for the pan? els, and can effectively delay the crack displacement of panels, satisfy the needs of relatively large structural lateral deformation and satisfied the requirement for seismic resistance of non-structure components in codes.

Abstract:A nonlinear spring-friction bearing (NFB) composed of a nonlinear conical spring and a plane slip bearing was proposed. The theoretical model of the bearing was established based on the structural characteristics and working principle of the bearing. The solid model of the bearing was established using the finite element soft? ware, the hysteretic properties, and stress distribution of the bearing were studied. The influence of the key param? eters of the cone spring on the hysteretic characteristics was analyzed. The time-history analysis of single-layer spherical reticulated shells with NFB and common fixed-stiffness sliding bearings under three-direction seismic ac? tion was carried out to investigate the isolation performance, and the isolation coefficient was introduced to evaluate the overall isolation effect of the structure. The results show that the NFB can effectively reduce the seismic response of the reticulated shell structure under multi-dimensional earthquakes. It has better joint relative displacement, bear? ing displacement control ability, and bearing self-reset ability when compared with the fixed stiffness slip bearing.

Abstract:The phenomenon of secondary salinization caused by water and salt migration of subgrade soil has been observed to take place in Northwest China. To clarify the dynamic rebound characteristics of the coarse-grained sulfate saline soil (CGSSS) subgrade under the influence of load, humidity, and salinity, indoor dynamic triaxial tests were conducted to study the evolution law of dynamic resilient modulus of CGSSS under fifteen stress paths, three wa? ter contents and four salt contents. The test results show that the dynamic resilient modulus of CGSSS with the same humidity increases with the increase of confining pressure and bulk stress, but with the increase of the deviator stress, the dynamic resilient modulus shows a lower development trend. The salt content first increases and then de? creases, and the high salt content increases. At the same time, the higher salt content results in the more obvious the influence of deviator stress and bulk stress on the dynamic resilient modulus; under the same stress level, the dy? namic resilient modulus of CGSSS increases gradually with the increase of water content and salt content, and the ef? fect of salt tends to be more significant than that of water. Based on the stress dependence of dynamic resilient modu? lus revealed by the test, two widely applicable theoretical models are selected from typical three-parameter compos? ite models related to stress, and then the best prediction model is compared. The error analysis shows that the ob? tained Ni model has higher rationality and reliability, and a parameter prediction formula of the model with higher precision is established. Through the further comparative analysis of the predicted value and the experimental value, the accuracy of the parameter prediction formula of the model is verified, which is suitable for predicting the dynamic resilient modulus of CGSSS. The research results can provide dynamic parameters for the structural design of sub? grade and pavement in saline soil areas.

Abstract:In order to solve the problem that the weak mucky soil cannot be directly used for subgrade filling, it is necessary to explore an excellent curing agent formula. First，blast furnace slag, fly ash, and calcium carbide slag were selected as curing materials to reinforce the Taizhou mucky soild. Next, by texting unconfined compressive strength, the regression equations of 14 d and 28 d ages were obtained using the method of mixture test analysis. It was found that the mass fraction ratio of the curing agent which is called ZX20 at the best ratio was as blast furnace slag∶fly ash∶calcium carbide slag = 42.1∶11.5∶46.4. The strength of ZX20 solidified soil at 28 d age was 1 479.32 kPa. Then, by texting unconfined test, water stability test, and dry-wet cycle test on ZX20 solidified soil and limelime soil, the results showed that ZX20 solidified soil met the requirements of subgrade filling strength and had higher strength, better road performance water stability and dry-wet cycle than traditional lime-lime soil. Next, it was found that the logarithmic function had a good fit for the relationship between the strength of ZX20 solidified soil and age. Finally, by using the SEM method and PCAS software, the microscopic mechanism of ZX20 solidified soil was analyzed qualitatively and quantitatively. It was found that a large number of filaments, needles, and floccules were generated in the solidified soil with age, and the large pores were divided into small pores and filled partial pores, thereby increasing the strength of the solidified soil.

Abstract:In order to study the effect of mechanical behavior of steel H-pile foundation in integral abutment jointless bridges (IAJBs) by unbalanced earth pressure and asymmetric loading, several reciprocating low-cycle pseudo-static tests on studying the soil-steel H-pile interaction were carried out under symmetric conditions (both balance earth pressure and symmetric loading), only unbalance earth pressure (symmetric loading) and completely asymmetric conditions (both unbalance earth pressure and asymmetric loading), respectively. A comprehensively comparative study was performed to find their behaviors in terms of horizontal deformations, soil resistance, strain, and bending moment of piles. The test results indicate that the horizontal deformation of positive loading is signifi cantly different from that of negative loading under completely asymmetric conditions. In addition, the soil resistance and bending moment of the pile are significantly larger than those of negative loading under positive loading. The un? balance earth pressure and asymmetric loading have a significant impact on the horizontal deformations, soil resis? tance, and the bending moment of the pile. Among them, the unbalance earth pressure induces the overall negative ac? cumulative deformation and increases the soil resistance and the bending moment of the pile. The positive asymmetric loading decreases the horizontal deformation but increases the soil resistance and bending moment of the pile. The negative asymmetric loading decreases the horizontal deformation, soil resistance and bending moment of the pile.

Abstract:The study investigated the influence factors of the ultra-high performance seawater sea-sand con? crete (UHPSSC), and optimized its overall performance. The orthogonal experiments were first conducted to study the effects of water binder ratio, sand binder ratio, silica fume content and fly ash content on the mechanical properties and fluidity of UHPSSC, and the optimal mix design is obtained. Then, based on the optimal mix proportion from the orthogonal test, the effects of volume fraction and short-cut fiber type on the mechanical properties of UHPSSC were studied, including polypropylene fiber, polyvinyl alcohol fiber, basalt fiber, alkali resistant glass fiber, ultra-high molecular weight polyethylene fiber and steel fiber. The results show that the most influential factors on the fluidity, the flexural strength and the compressive strength are water binder ratio, water binder ratio and fly ash content. Based on the comprehensive evaluation of mechanical performance and flowability, the optimized mix design is the dosage of cement, silica fume, fly ash, water and sea sand per cubic meter of concrete is 491 kg，140 kg，70 kg，112 kg and 631 kg, respectively. Meanwhile, the enhancing effect of steel fiber on the mechanical performance of UHPSSC is most ob? vious.

Abstract:In order to reduce the occurrence of cracks in the cast-in-situ concrete structure of the laminated wall panel in the subway assembly underground station, the expansion agent and the internal curing agent compound technology were adopted. Four groups of C40 concrete with benchmark group, single-mixed expansion agent, com? bined expansion agent, and light sand internal curing agent or SAP were designed. Through the concrete limited ex? pansion rate, auto-shrinkage and drying shrinkage and other deformation properties and large slab crack resistance test, the influence of the cooperative expansion effect of light sand internal curing agent on the deformation perfor? mance of micro-expansion concrete was studied. The results show that the light sand internal curing agent has the characteristics of high strength, high water absorption, high density, and can be evenly distributed in the concrete. The 14 day limited expansion rate of the shrinkage-compensating concrete mixed with light sand internal curing agent is increased by 72% compared with the group without the internal curing agent. The 60 day self-shrinkage is still in the expanded state, the expansion rate is 153×10-6，the crack resistance is significantly improved, and the overall performance is significantly better than that of the SAP internal curing agent. The synergistic expansion effect of internal curing agents on expansive concrete is proposed for the first time.

Abstract:In order to study whether the rice husk ash can be used as filler in cold recycled emulsified asphalt mixture, different amounts of rice husk ash and mineral powder were added into the mixture as experimental group and control group. The mechanical properties, low-temperature properties, high-temperature properties, and water stability of the mixture were tested by indirect tensile test, low-temperature splitting test, high-temperature rutting test, and freeze-thaw splitting test, respectively. The microstructure and main elements of rice husk ash were ob? tained by scanning electron microscope and EDX energy spectrum analysis. The results show that rice husk ash has a larger specific surface area, higher porosity, and amorphous silica content. Compared with mineral powder, rice husk ash can improve its high-temperature and mechanical properties when added into the cold regenerated mixture. In or? der to meet the requirements of low-temperature performance and water stability, the percentage of rice husk ash as a filler should not exceed 3% of aggregate and other filler mass sum. The conclusion is that it is feasible to add rice husk ash into cold recycled emulsified asphalt mixture as the road base in arid and non-cold regions.

Abstract:In order to study the effect of the application of air carrying energy radiant air-conditioning system （ACERS）in laboratory animal rooms on animal welfare and energy saving of air-conditioning system，Fluent soft? ware is used to numerically simulate the operating state of traditional air-conditioning system and ACERS. The distri? bution differences of wind speed，temperature and humidity and ammonia concentration under the same ventilation times，and the effects of different ventilation times of ACERS on indoor wind speed，temperature and humidity and ammonia concentration are compared and analyzed. It is found that the ACERS can keep the temperature gradient in the laboratory animal rooms below 0.46 ℃/m and the relative humidity between 40%~70%，and because the control of fresh air can improve the problem of high energy consumption in the laboratory animal rooms to a certain extent. This provides a reference for the welfare of laboratory animals and the energy saving of laboratory animal rooms.