141 results about "Dynamic modulus" patented technology

Methods of controlling the durability of and / or the amount of air in concrete formulations that include combining cement, water, and optionally aggregates, admixtures and / or additives to form a cement mixture; and adding prepuff particles to the cement mixture to form a concrete formulation. The prepuff particles have an average particle diameter of from 0.2 mm to 3 mm, a bulk density of from 0.015 g / cc to 0.35 g / cc, an aspect ratio of from 1 to 3, and a smooth continuous outer surface. The cured and hardened concrete formulation typically has a relative dynamic modulus of at least 70% determined according to Procedure A of ASTM C666 (2003). The amount of air in the concrete typically increases over the amount of air in similar formulations not containing prepuff particles, as determined according to ASTM C231, based on the volume percent of prepuff. The concrete formulations can be used to make articles.

The invention belongs to the field of road engineering, and particularly relates to a hyperviscous and high-elastic asphalt modifier applicable to steel bridge deck pavement. The asphalt modifier comprises the following raw materials in parts by weight: 3-10 parts of junked tire rubber powder, 3-10 parts of polyethylene wastes, 3-8 parts of styrene-butadiene-styrene block copolymer, 1-5 parts of styrene-isoprene-styrene block copolymer, 1-5 parts of terpene resin, 5-10 parts of solvent naphtha, and 0.3-0.7 part of alcohol ether carboxylate adhesion agent. In addition, a modified asphalt and amodified asphalt mixture are prepared on the basis of the modifier, the 60 DEG C dynamic viscosity of the modified asphalt prepared by applying the modifier can reach more than 300000Pa.s, and the performance grading reaches PG 88-28; and the asphalt mixture has favorable water stability, higher dynamic modulus, higher track dynamic stability and low temperature failure strain, and can resist complicated mechanics and temperature environment of a steel bridge deck.

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.

Fiber-reinforced polymer composites possessing improved damping ability are provided. In one aspect, the fibers provide the composite with a relatively high dynamic modulus over a broad range of frequencies for a given temperature. In another aspect, the polymer may comprise a viscoelastic polymer possessing a relatively high loss factor for a given frequency and temperature. The polymer may be further tailored to control the center frequency at which the maximum loss factor of the polymer is achieved. The composite so formed exhibits a relatively small reduction in loss factor with significant increase in dynamic modulus over a broad range of frequencies for a given temperature. As a result, a structure damped by the composite exhibits a relatively high, constant loss factor as compared to conventional damping materials. Thus, embodiments of the disclosed composites dissipate significantly more energy during each vibration cycle than conventional damping materials.

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.

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.

The invention belongs to the technical field of preparation of modified asphalt and in particular relates to high-modulus asphalt and a preparation method thereof. The high-modulus asphalt is composed of asphalt, a polystyrene-polybutadiene segmented copolymer thermoplastic elastomer and an auxiliary agent, wherein the asphalt comprises high label asphalt and low label asphalt, the internal mixing amount of the low label asphalt in the high label asphalt is 10-80wt%, the internal mixing amount of the polystyrene-polybutadiene segmented copolymer thermoplastic elastomer in the asphalt is 2-7wt%, and the external mixing amount of the auxiliary agent is 0.51-15wt%. Compared with the prior art, the high-modulus asphalt has high dynamic modulus and good track resistance and is easy to prepare, processing flow is short, processing equipment is simple, technological conditions are mild, production is quick, and the modification cost is low.

The invention discloses a method for separating the influences of fatigue damage and a thixotropic factor on an asphalt modulus, which relates to a testing method for the asphalt modulus and is used for solving the problem of limitation on the conventional analysis of the asphalt fatigue characteristic under the action of cyclic load with a damage theory. The method comprises the following steps of: drawing a standard relation curve of an asphalt dynamic modulus and a phase angle, testing relation curves of the dynamic modulus and the phase angle under different initial strain conditions, finding a turning point which is deviated from a linear section on each curve, finding a dividing point between a thixotropy influence area and a damage influence area, and fitting curve parts in front of the dividing point to obtain the values of k, alpha and beta; and fitting the dynamic modulus of asphalt to obtain a value D, and separating the dynamic modulus of the asphalt into two parts, i.e., a modulus under the influence of thixotropy and the reduction value of the modulus caused by damage. The method is used for researching the fatigue characteristic of asphalt.

The invention discloses an asphalt mixture dynamic modulus testing method comprising the steps that: 1, with an asphalt mixture rotation compaction instrument, an asphalt mixture sample is formed; and through cutting, an asphalt mixture cylindrical sample with a fixed size is obtained; 2, two pressure heads are prepared; the sample and the two pressure heads are plated into an environment box with a target temperature; and the temperature is maintained for 5h; 3, the two pressure heads and the sample are fetched; the two pressure heads are respectively placed at central positions on two ends of the cylindrical sample; and sinusoidal axial compressive stress is applied to the sample with different frequencies under a specified test temperature; and 4, during the loading process, applied stresses and generated axial strains at corresponding times are determined, and the dynamic modulus is a ratio of the amplitude of sinusoidal load to the amplitude of generated sinusoidal strain. According to the method provided by the invention, with the local loading test, lateral restraint of the asphalt mixture in an actual pavement can be effectively simulated. The test device is simple, the operation is easy, and the method can be popularized.

Methods of controlling the durability of and / or the amount of air in concrete formulations that include combining cement, water, and optionally aggregates, admixtures and / or additives to form a cement mixture; and adding prepuff particles to the cement mixture to form a concrete formulation. The prepuff particles have an average particle diameter of from 0.2 mm to 3 mm, a bulk density of from 0.015 g / cc to 0.35 g / cc, an aspect ratio of from 1 to 3, and a smooth continuous outer surface. The cured and hardened concrete formulation typically has a relative dynamic modulus of at least 70% determined according to Procedure A of ASTM C666 (2003). The amount of air in the concrete typically increases over the amount of air in similar formulations not containing prepuff particles, as determined according to ASTM C231, based on the volume percent of prepuff. The concrete formulations can be used to make articles.

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.

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.

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.

The invention relates to a method for predicting the dynamic modulus of an asphalt mixture and application of the method. The method comprises steps of carrying out a dynamic frequency scanning test on the samples with different aging degrees; measuring a plurality of shear moduli under different test temperatures and loading frequencies; obtaining indexes such as cross modulus, cross frequency, rheological parameters and the like in different aging states according to the asphalt complex shear modulus, the phase angle, the energy storage modulus and the loss modulus so as to rotate and translate the asphalt complex shear modulus and the phase angle main curve, and establishing the asphalt complex shear modulus and the phase angle main curve in a wide aging temperature and aging time range; therefore, the dynamic modulus E * of the asphalt mixture can be predicted, and a basis is provided for determining the preventive maintenance time of the asphalt pavement.

The invention discloses a method for testing the dynamic modulus of asphalt concrete and a device thereof. The device comprises: acquiring a hollow cylindrical asphalt concrete test piece, the two end faces of which are mutually parallel and horizontal; installing an intensifier inside the hollow cylindrical asphalt concrete test piece, then placing the test piece in a thermostatic alcohol bath, utilizing a cooling device to make the temperature of the alcohol bath reach a required test temperature, which is set according to the research purpose and requirement of an experimenter; controlling a hydraulic pump and a transmission device with computer software, and providing internal annular pressure to the inner cavity of the hollow cylindrical asphalt concrete test piece through the intensifier; testing an annular pressure value and an average elastic strain so as to provide relevant data for calculating a dynamic modulus, and keeping a loading waveform unchanged during acquisition. The device consists of a cooling device, an alcohol bath, an intensifier, a hydraulic pump and a transmission device, as well as a data acquisition system. The method and device of the invention have the advantages of simple operation and high accuracy.

An apparatus for the compaction of roadway materials includes a compaction analyzer for calculating stiffness during construction of the roadway. The apparatus generates a dynamic modulus for each layer of a roadway which can be used to calculate the overall effective modulus. A method for determining stiffness includes generating a dynamic modulus for each layer and calculating the overall effective modulus using the modulus of each layer.

The invention relates to coated optical fibers comprising soft primary coatings and to such primary coatings for protecting glass optical fibers having a sufficient high resistance against cavitation. In particular, the primary coatings have a cavitation strength at which a tenth cavitation appears (sigma<10>cav) of at least about 1.0 MPa as measured at a deformation rate of 0.20% min<-1 >and of at least about 1.4 times their dynamic modulus at 23° C. The coating preferably shows strain hardening in a relative Mooney plot, preferably has a strain energy release rate Go of about 20 J / m<2 >or more, and preferably has a low volumetric thermal expansion coefficient. The invention furthermore provides a method and apparatus for measuring the cavitation strength of a primary coating.

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.

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.

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.

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.

Rubber articles, including tires and tire treads, that are manufactured from a rubber composition that includes a functionalized styrene-butadiene rubber (SBR) and a polybutadiene rubber, wherein the functionalized SBR includes a functional group attached as an active moiety and wherein the butadiene portion of the SBR has as trans-1,4 content of between 30 wt. % and 70 wt. %. The rubber composition further includes a plasticizing system having a plasticizing resin having a glass transition temperature (Tg) of at least 25° C. and a plasticizing liquid, wherein the plasticizing system is added in an effective amount to provide the rubber composition with a glass transition temperature of between −25° C. and −15° C. and with a dynamic modulus G* at 60° C. of between 0.8 MPa and 1.3 MPa. The rubber composition is reinforced with a silica filler.

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.

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.

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.

The invention discloses a speed-competing tread rubber for a motorcycle.The speed-competing tread rubber for the motorcycle is prepared from, by weight, 70-100 parts of emulsion polymerized styrene-butadiene rubber, 30-60 parts of solution polymerized styrene-butadiene rubber, 10-25 parts of operation oil, 70-100 parts of high-hysteresis carbon black, 1-3 parts of stearic acid, 3-6 parts of zinc oxide, 2-4 parts of an anti-aging agent, 1-3 parts of microcrystalline wax, 2-5 parts of tert butyl phenolic resin, 4-7 parts of tackifying resin, 1-2.5 parts of sulphur powder and 2-3.5 parts of a promoting agent.By means of the speed-competing tread rubber for the motorcycle, the tread rubber can generate extremely high hysteresis loss in a high-speed movement state of the motorcycle, meanwhile, extremely high dynamic modulus can be kept, friction force between a tread and the ground is increased, a tire has outstanding grip performance and manipulation performance, the defect that the abrasion resistance of the tread is poor can be effectively avoided, optimal performance balance is achieved, and maximization of benefits of a user is achieved.

The invention discloses a permanent pavement design method which belongs to the field of road engineering. The method comprises the following steps: using asphalt mixture ultimate tensile strain as a design index, using a vehicle axle load spectrum, a pavement temperature field and a pavement material dynamic modulus as design parameters, and combining a computer simulation technology and an elastic laminar mechanics theory to obtain pavement structural strain distribution approaching to a true state so as to accurately predict the pavement life and design a pavement structure with long life. Compared with a traditional design method, the invention solves the important technical difficult problem that the pavement structure designed by the traditional design method needs periodic reconstruction, realizes the goals of durability, economy and environmental protection of the pavement structure and has good popularization and application value.

Starter-alternator assembly including a poly-V belt comprising a body made of elastomeric material, a plurality of filiform resistant inserts longitudinally embedded in the body, and a coupling portion integrally connected to the body and comprising a plurality of V-shaped ribs set alongside one another and alternating with V-shaped grooves. The belt has a dynamic modulus, with a tensile force pre-set at 600 N at a frequency 15 Hz, that after 10 000 cycles is higher than 110 000 N / rib / branch, and is advantageously made with resistant inserts obtained from at least one first fibre material and one second fibre material.

A tire tread formed from a rubber composition having a functionalized SBR and a BR that is reinforced with between 95 phr and 125 phr of a silica filler and includes a plasticizing system to adjust the glass transition temperature to be between −30° C. and −15° C. and the dynamic modulus G* at 60° C. to be between 0.9 MPa and 1.15 MPa. The tread includes central tread blocks having an average central tread block length of between 6.5 mm and 10 mm and shoulder tread blocks having an average shoulder tread block length of between 10 mm and 20 mm. Furthermore the tread is limited to being between 6.5 mm and 7.7 mm thick. In particular embodiments the rubber composition may be just the functionalized SBR.

The invention relates to a tyre (1) comprising at least two sidewalls (3), a crown (2) provided radially externally with a tread, a carcass-type reinforcing structure (7) and a crown reinforcement, the inner surface of the sidewalls (3) and the crown (2) forming an inner wall of the tyre. According to the invention, at least one portion of said wall is covered with a self-sealing ply (11) comprising a styrene thermoplastic (TPS) elastomer and the tyre can have a given working inflation pressure Pg. The invention is characterised in that, for any temperature within a given temperature range of between +30 DEG C and +100 DEG C, the self-sealing ply (11) has a loss factor tg delta of less than 0.2 and a dynamic modulus G* of less than Pg, tg delta and G* being measured at a frequency of 10 Hz.