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140 results about "Dynamic modulus" patented technology

Dynamic modulus (sometimes complex modulus) is the ratio of stress to strain under vibratory conditions (calculated from data obtained from either free or forced vibration tests, in shear, compression, or elongation). It is a property of viscoelastic materials.

Fatigue life prediction method for high-modulus asphalt mixture pavement

InactiveCN104462843AAccurately describe attenuationAccurately describe the lawSpecial data processing applicationsUltrasound attenuationElement model
The invention provides a fatigue life prediction method for a high-modulus asphalt mixture pavement. The method comprises the steps that structural temperature distribution, pavement material dynamic modulus and temperature axle load distribution of the high-modulus asphalt mixture pavement serve as basis parameters; a fatigue strain equation is fit according to an indirect tension fatigue test result; ANSYS software is adopted to construct a pavement structure finite element model, and maximum tension strain of a bottom layer at different axle load levels in different temperature regions is calculated; according to the Miner fatigue cumulative damage rule, fatigue cumulative damage results of a high-modulus asphalt mixture at different axle loads and different temperatures are calculated according to the formula: . The fatigue life prediction method for the high-modulus asphalt mixture pavement has the technical advantages that temperature gradients and axle load distribution of the asphalt mixture pavement are fully considered, an accurate prediction model is established, the process and law of fatigue attenuation of the asphalt mixture are accurately described, the application range is wide, and calculation results are reliable, so a more reliable method is provided for structural design of the asphalt pavement.
Owner:CHONGQING JIAOTONG UNIVERSITY

High-modulus bituminous mixture additive and preparation method thereof

The invention discloses a high-modulus bituminous mixture additive and a preparation method thereof. The high-modulus bituminous mixture additive is composed of a modifying main agent, butadiene styrene rubber, polyethylene paraffin, a filling material, an anti-aging component, and a plasticizing component according to a mass percentage of 100:(10-30):(15-40):(40-80):(2-6):(5-20); wherein the modifying main agent consists of one or more components selected from waste PE, polypropylene, and EVA. The preparation method comprises the following steps: evenly mixing the modifying main agent, butadiene styrene rubber and polyethylene paraffin at a temperature of 160 to 190 DEG C, adding the filling material, anti-aging component and plasticizing component into the mixture, evenly mixing under a certain rotation speed, then extruding the mixture by a screw extruder, cooling at the room temperature, and finally cutting into particles. The high-modulus bituminous mixture additive is mainly applied to pavement projects such as new construction and reconstruction of high grade roads and heavy traffic roads, can improve the dynamic stability, static modulus, dynamic modulus and shearing resistant performance of bituminous mixture, thus prominently reduces the damages of rut, displacement, or the like, and can improve the low-temperature anti-cracking performance of high-modulus bituminous mixture at the same time.
Owner:SHANGHAI MUNICIPAL ENG DESIGN INST GRP

High-modulus bituminous mixture admixed with waste material, preparation method and method for preparing mixture specimen

ActiveCN103113044AImprove dynamic modulusImproved dynamic stabilitySolid waste managementRoad surfaceAsphalt
The invention discloses high-modulus bituminous mixture admixed with waste material, a preparation method and a method for preparing mixture specimen. The high-modulus bituminous mixture admixed with the waste material comprises aggregate, mineral powder and TLA modified asphalt, wherein the aggregate comprises waste material obtained after milling roads and new aggregate. The TLA modified asphalt comprises matrix asphalt and lake asphalt, wherein the mass of the waste material is 30%-70% of the total mass of the high-modulus bituminous mixture; if the aging asphalt in the waste material and the TLA modified asphalt are adopted as a complete binding material, the mass rate of the binding material to the aggregate is 4.5%-6.5%, and the mass fraction of the TLA modified asphalt is 4.3%-6.1% of the high-modulus bituminous mixture; the mass of the lake asphalt is 30%-50% of the total mass of the TLA modified asphalt; the mass of the mineral powder is 0.5%-4% of the total mass of the high-modulus bituminous mixture; and the residue is the new aggregate. The high-modulus bituminous mixture admixed with the waste material has the characteristics of high dynamic modulus, good deformation performance, high dynamic stability and good fatigue property; and the high-modulus bituminous mixture admixed with the waste material achieves the dual goals of realizing the regeneration of the waste material at high proportion and solving the rutting diseases on pavements.
Owner:SOUTHEAST UNIV

Parameter identification method of asphalt viscoelastic model based on comprehensive data optimization criterion

The invention provides a parameter identification method of an asphalt viscoelastic model based on a comprehensive data optimization criterion and belongs to the technical field of a parameter identification method of an asphalt viscoelastic model. The method comprises a step of carrying out a dynamic frequency scanning test, a static creep test and a stress relaxation test on asphalt by using a dynamic shear rheometer, establishing a dynamic modulus main curve and a phase angle main curve based on the test data, and drawing a creep compliance-time curve and a relaxation modulus-time curve, astep of establishing the asphalt viscoelastic model and deriving an expression of each viscoelastic parameter, which is a fitting value of the model, and a step of identifying model parameters according to the comprehensive data optimization criterion, thus modifying the model parameters, and taking a set of parameters corresponding to a smallest sum-of-squared differences to be parameter values in a final model. According to the method, the dynamic and static viscoelastic properties of the asphalt are comprehensively considered, and the method has important significance for the comprehensivecharacterization of the viscoelastic performance of an asphalt material by the model and the design and maintenance of an asphalt pavement.
Owner:HARBIN INST OF TECH

Ballastless track-structured waterproof vibration-reducing flexible protecting structure and paving method thereof

ActiveCN105714621ADrain fastComprehensive three-dimensional waterproof protectionRailway tracksSurface layerBridge deck
The invention discloses a ballastless track-structured waterproof vibration-reducing flexible protecting structure and a paving method thereof. A waterproof linking layer and a buffer protecting layer are paved between the bottom of a ballastless track foundation plate and the top surface of a surface layer/bridge deck slab of a roadbed in a full-width manner. According to the ballastless track-structured waterproof vibration-reducing flexible protecting structure, by virtue of the linking layer and the buffer protecting layer which are paved on the full fracture surface, the overall stereoscopic water proofing and the integrality are realized; by regulating the dynamic modulus, the damping characteristic and the deformation adaptability of an asphalt concrete protecting layer by virtue of a special modifying enhancer, the rigidity matching and buffer vibration reducing functions are realized; and by enhancing the load diffusivity, the fatigue durability and the water damage resistance of asphalt concrete by virtue of the special modifying enhancer, the problems of premature failure, interlayer slurry extruding, disengaging, even frost heaving and the like of waterproof layers of existing ballastless track roadbeds are effectively solved, the integrality, the smoothness, the uniformity and the long-term stability of a lower base structure of a track are improved, and good and stable support is provided for a ballastless track plate, so that the fatigue life of the track plate is prolonged. The ballastless track-structured waterproof vibration-reducing flexible protecting structure is a long-lasting protection scheme.
Owner:SOUTHEAST UNIV +2

Asphalt mixture viscoelastic property test method based on wheel load instrument

The invention relates to an asphalt mixture viscoelastic property test method based on a wheel load instrument. In the method, the wheel load instrument, a test piece, a dynamic modulus test and a creep test are provided. The method comprises the following steps: a, before the test, assembling a strain sensor at the bottom of an asphalt mixture test piece and calculating by a mechanical method or a finite element analysis method to obtain the stress distribution condition of the test piece under the action of moveable load according to moving wheel load features and the test piece size; b, during the test, employing the modulus test and the creep test: measuring the tensile deformation strain capacity of the test piece by using the strain sensor, and measuring the tensile deformation strain capacity of the test piece through the strain sensor; and c, after the test, obtaining the stress and the strain capacity of the test piece and the action time of the wheel load by the wheel load instrument and the strain sensor. The method has the characteristics of simplicity, practicability, high operability and high applicability. According to the method, the stress characteristic of the test piece during the test is similar to the actual asphalt concrete road surface, and the viscoelastic property obtained by the test is accurate and reliable.
Owner:CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY +1

Method for characterizing degrees of miscibility of old and new asphalt based on dynamic moduli of mixtures

The invention relates to a method for characterizing the degrees of miscibility of old and new asphalt based on dynamic moduli of mixtures. The method includes the steps that various performance indexes of RAP materials, matrix asphalt, aggregates and mineral powder are tested; hot mixing regenerated asphalt mixtures and specimens are prepared according to a current regeneration norm; the dynamicmodulus of each specimen is tested and a principal curve of the actually measured dynamic moduli is drawn; asphalt mortars with different degrees of miscibility of the old and new asphalt are preparedby adding different addition amounts of old asphalt and regenerating agents into the matrix asphalt; DSR tests are carried out on the different asphalt mortars to measure composite moduli and phase angles of the asphalt mortars; the dynamic moduli of the mixtures with different asphalt mortar states is predicted and the predicted principal curve of the dynamic moduli is drawn; and the degrees ofmiscibility of the old and new asphalt in regenerated mixtures are characterized. According to the method for characterizing the degrees of miscibility of the old and new asphalt based on the dynamicmoduli of the mixtures, the method of performance indirect testing with the greatest controllability is selected for research, influences of mixing factors, human errors and mineral aggregate gradation are eliminated as far as possible, and the test precision is improved.
Owner:BEIJING UNIV OF CIVIL ENG & ARCHITECTURE

Detection method for noise reduction performance of asphalt concrete by using ultrasonic testing apparatus

InactiveCN103344702AReflect vibration and noise reduction performanceQuick evaluationAnalysing solids using sonic/ultrasonic/infrasonic wavesEngineeringRoad surface
The invention provides a detection method for the noise reduction performance of asphalt concrete by using an ultrasonic testing apparatus, which belongs to the field of evaluation methods for the noise reduction performance of a road pavement material. According to the method, a standard asphalt concrete test sample with known length of L and volume density of Rho is adopted; two ends of the test sample are connected with two transmitting ports of a nonmetal ultrasonic tester respectively through an ultrasonic transmitting transducer and an ultrasonic receiving transducer; the transmission time of measuring ultrasonic waves from transmitting transducer to receiving transducer is t, the transmission speed v of the ultrasonic waves in the test sample is calculated based on the known length L, and the dynamic modulus E of the asphalt concrete test sample is calculated based on the theoretical calculation formula of the dynamic modulus E which is capable of characterization of noise reduction performance of a tested material, wherein E is equal to Rho(1+mu)(1-2mu)v<2>/(1-mu); and noise reduction performance of a related road pavement asphalt concrete material is indirectly evaluated based on the calculated value of the dynamic modulus E. The method provided by the invention has the advantages of easiness, feasibility, reliable data and capacity of rapidly finishing comparison and evaluation of noise reduction performance of related pavement asphalt concrete materials.
Owner:WUHAN MUNICIPAL ENG DESIGN & RES INST

Method and device for detecting solid fraction and final stage of solidification of continuously cast slab

The invention discloses a method for detecting solid fraction and final stage of solidification of a continuously cast slab. The method comprises the following steps of: (1) applying oscillation excitation to the continuously cast slab, so that the continuously cast slab generates elastic deformation under oscillation excitation; (2) measuring the strain of elastic deformation of the continuously cast slab, the stress loads applied on the continuously cast slab by oscillation excitation, and the stress/strain phase difference of elastic deformation of the continuously cast slab with oscillation excitation after the continuously cast slab generates resonance to oscillation excitation; (3) calculating dynamic modulus of the continuously cast slab; and (4) obtaining the solid fraction and final stage of solidification of the continuously cast slab according to a solid fraction and dynamic modulus characteristic curve of the continuously cast slab. The invention also discloses a device for detecting solid fraction and final stage of solidification of a continuously cast slab. The method and the device provided by the invention can conduct nondestructive online measurement on the continuously cast slab, and can improve the solid fraction detection accuracy as well as the location accuracy of final stage of solidification of the continuously cast slab.
Owner:中冶赛迪电气技术有限公司

Asphalt mixture tension dynamic modulus measurement method

InactiveCN107748106AEvaluation of Mechanical Response PropertiesEliminate eccentric tensionMaterial strength using tensile/compressive forcesEngineeringRoad surface
The present invention discloses an asphalt mixture tension dynamic modulus measurement method, which comprises that an upper metal base and a lower metal base are respectively adhered and fixed on theupper end and the lower end of a prepared asphalt mixture cylinder specimen, the lower metal base is fixed on a loading device, the upper metal base is connected to a metal loading rod, and three displacement sensors are vertically arranged at the middle portion of the side surface of the asphalt mixture cylinder specimen according to the circumference at equal intervals; sine wave or haversine axial tension stress is applied on the specimen through the metal loading rod at a specified test temperature and a frequency; and during the loading, the corresponding axial tension stress and the corresponding axial tension strain are collected, and the dynamic modulus is calculated. According to the present invention, the dynamic modulus property of the asphalt mixture is determined under the direct tension force applying mode, such that the mechanical response characteristics of the asphalt mixture can be well and completely evaluated, the test foundation can be established for the asphaltpavement mechanical calculation and the fatigue crack analysis and checking computation, and the method has advantages of simple operation and reliable data, and is easy to promote and use.
Owner:RES INST OF HIGHWAY MINIST OF TRANSPORT

Permeability-based ultrasonic verification method of asphalt pavement preventative maintenance opportunity

The invention discloses a permeability-based ultrasonic verification method of asphalt pavement preventative maintenance opportunity. The method comprises the steps as follows: firstly, building an indoor asphalt mixture damage-permeability model, which comprises steps as follows: a, taking test pieces to perform different degrees of uniaxial compression and diametral compression tests, so as to obtain different types and degrees of damage, b, respectively performing dynamic modulus testing on the test pieces before and after being damaged, so as to obtain damage D indicated by dynamic modulus, c, performing ultrasonic testing on the test pieces before and after being damaged, so as to obtain damage Du indicated by ultrasonic variation, building the relation between Du and D, and simultaneously performing dimension modification on Du by testing the test pieces at different heights, d, building an ultrasonic damage-permeability model, and e, obtaining the asphalt mixture damage threshold value of preventative maintenance and the ultrasonic wave speed threshold value corresponding to the asphalt mixture damage threshold value; and secondly, verifying the asphalt pavement preventative maintenance opportunity. The method can accurately judge pavements in advance, delay the development of pavement diseases, prolong the service life of the pavements, and save cost.
Owner:SHANDONG UNIV

Method for designing and evaluating dense-grading large stone asphalt mixture

The invention relates to a method for designing and evaluating a dense-grading large stone asphalt mixture. In the method for designing and evaluating the performance of an LSAM (large stone asphalt mixture) structure, a key point for forming a squeezed compact structure is arranged according to the squeezing and filling characteristics of aggregate grading, and new volume design and separation-resistant design control indexes of a [CA'] ratio, a [FAc'] ratio and an [FAf'] ratio are proposed, and the optimal asphalt use amount is determined by combining with a Superpave level 1 volume design method. Mechanical design indexes CEI (Compaction Energy Index) and TDI (Traffic Densification Index) are introduced into to evaluate structural resistance, a dynamic modulus and a main curve thereof are introduced in to evaluate the high-temperature permanent deformation resistance performance of the LSAM, a low-temperature bending strain energy density is introduced in to evaluate the low-temperature crack resistance of the LSAM, and a site coring is introduced for a hamburg wheel tracking test to check the pavement performance of the LSAM after paving. According to the method, the problem of resisting tracks and fatigue for extra-heavy asphalt pavements can be solved, and the service life of the pavement is prolonged.
Owner:SHANXI PROVINCIAL RES INST OF COMM

Method for detecting dynamic modulus of each layer of asphalt pavement and adhesion device

The invention relates to a method for detecting dynamic modulus of each layer of an asphalt pavement and an adhesion device. The method comprises the following step of detecting the dynamic moduli of an upper surface layer, a middle surface layer and a lower surface layer of an original pavement. According to the method disclosed by the invention, an SPT (Simple Performance Tester) or a loading device which is capable of applying offset sine wave type or haversine wave form load, is in a frequency range of 0.1 to 25 Hz, can achieve 2800KPa of maximum stress application level and is capable of achieving 5N of loading resolution ratio is adopted. Offset sine wave or haversine wave type axial pressure stress is applied to each core sample layer, restorable axial strain of a testing piece can be measured, and uniaxial compression dynamic modulus within an online viscoelasticity range of each layer of the asphalt pavement in service can be calculated. Harsh requirements of an existing dynamic modulus detecting device on sizes of core samples are met; according to the method, the measurable thickness range of the core samples is 3 cm to 15 cm, and the method can be used for calculating material parameters of each layer of an existing asphalt pavement, evaluating the current situation of each layer of the asphalt pavement in service and forecasting the residual life of an old pavement.
Owner:JSTI GRP CO LTD
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