Showing papers on "Screed published in 2020"

Sand casting of sheet lead: numerical simulation of metal flow and solidification

Abstract: Sandcast lead sheets are characterised by their superior aesthetic performance and mottled surface. Lead sheet casting is widely used in the construction industry for roofing and flashing applications, while the roots of this process can be tracked back to the Roman times. In this study, two-dimensional computational fluid dynamics (CFD) simulations have been performed to simulate the melt flow and solidification stages of the lead sandcasting process. The effects of process parameters such as pouring temperature, screed velocity and clearance between the screed and the sandbed on the final quality of the lead sheet are investigated. Lead sheet quality has been quantified by measuring the variance and the average value of the final sheet thickness over the sandbed length. The developed CFD model has been validated against experimental results by comparing the time evolution of the lead-sandbed interface temperature against data collected by thermocouples during the real-time process. The numerical results show that all of the aforementioned parameters affect the final quality of the cast product and suggest that superior quality lead sheets can be produced for a range of relatively low values of the pouring temperature and slow strickle motion.

Experimental research and optimal control of vibration screed system (VSS) based on fuzzy control

Abstract: To enhance the compression performance and improve the paving quality of the VSS of the pavers, the experimental research of the VSS is performed to assess the VSS’s vibration stability under various excitations of the tampers and vibrator screed. A VSS’s dynamic model is also established to simulate and evaluate the VSS’s working performance. The root-mean-square (RMS) acceleration responses of the vertical and pitching motions at centre of gravity of the screed floor are chosen as the objective functions. In order to increase the VSS’s working performance, the dynamic parameters of the angular deviations of tampers are then controlled based on Fuzzy control. The research results indicate that the RMS value of the vertical screed motion is remarkably increased, concurrently the RMS value of the pitching screed angle is significantly reduced by controlling the angular deviations of tampers under different excitation frequencies of the VSS. Therefore, the VSS’s working performance is significantly improved in comparison without the control of the angular deviations.

A sensitivity analysis of the importance of the dynamic parameters on the paver’s performance

Abstract: In order to research the impact of the vibration on working stability of the vibration compaction system (VCS) and increase the paver’s performance, the acceleration responses at the screed surface under the excitation frequencies of the tampers and vibration screed are analyzed via the root mean square acceleration responses (RMSAR) at the bottom of the screed surface. A non-linear dynamic model of the VCS is then established to research the impact of the VCS’s dynamic parameters on the performance of paver via the objective functions of the vertical, pitch and roll RMSAR of the vibration screed. The dynamic parameters are then optimized based on a multi-objective genetic algorithm to enhance the paver’s performance. The experiment and simulation results show that the dynamic parameters greatly affect the paver’s performance. The compression performance is quickly increased, while the working stability and paving quality are reduced with increasing the angular deviations of tampers and excitation frequencies of both the tampers and vibration screed and vice versa. Also, the paver’s performance is significantly improved by using the optimal parameters of the VCS.

Vibration Analysis and Control of a Vibration Screed System for Asphalt Pavers

Abstract: To reduce shaking of a vibration screed system (VSS) and improve the paving performance of an asphalt paver (AP), the root-mean-square (RMS) acceleration responses at points on the front and rear screed floors are analyzed via an experimental method. A 3D nonlinear dynamic model of the VSS is also built to evaluate the influence of the dynamic parameters of the VSS on the compression efficiency, paving quality, and working stability of the AP based on the objective functions of the vertical, pitching, and rolling RMS values at the centre of gravity of the screed. The angular deviations, α and γ, of the tamper are then controlled to improve the paving performance. The research results show that the excitation frequency, ft, and both angular deviations, α and γ, of the tamper strongly affect the paving performance. The compression efficiency is quickly enhanced, while both paving quality and working stability are significantly reduced with increasing the excitation frequency ft and reducing the angular deviations. α and γ. and vice versa. Additionally, the screed shaking and paving performance of the AP are remarkably improved by control of the angular deviations, α and γ, under different working conditions.

Modeling Cyber-Physical System Object in State Space (on the Example of Paver)

Abstract: We has considered results of theoretical description of the cyber-physical system object’s model—asphalt paver with a compacting working body of increased efficiency based on the state space method are considered. The working body includes a tamper, screed and pressure bar. The mathematical model of the process of interaction of the object with the compacting road-building material takes into account the masses of the main structural elements of the working body and pavement. A rheological model of a viscoelastic Kelvin–Voight body is using to describe the compacted material. Suitability of developed mathematical model experimentally confirmed by simulation modelling of the system using program MATLAB/Simulink.

Neutron Radiography and Tomography of the Drying Process of Screed Samples.

Abstract: The moisture content of screed samples is an essential parameter in the construction industry, since the screed must dry to a certain level of moisture content to be ready for covering. This paper introduces neutron radiography (NR) and neutron tomography (NT) as new, non-destructive techniques for analysing the drying characteristics of screed. Our NR analyses evaluate the results of the established methods while offering much higher spatial resolution of 200 μm, thereby facilitating a two- and three-dimensional understanding of screed’s drying behaviour. Because of NR’s exceptionally high sensitivity regarding the total cross section of hydrogen the precise moisture content of screed samples is obtainable, resulting in new observations. The current methods to measure moisture content comprise the ‘calcium carbide method’, the ‘Darr method’, and electrical sensor systems.

Determination of readiness for laying based on material moisture, corresponding relative humidity, and water release

Abstract: The moisture content of the subfloor has to be determined before installation to avoid damages of the floor covering. Only if the readiness for layering is reached, an installation without damages can be expected in all cases. In general, three different approaches exist to measure the residual water content: determination of the moisture content, determination of the water release, or determination of the corresponding relative humidity. All three approaches are tested in laboratory at eight different screed types including two different samples thicknesses in each case. The moisture content and the water release are measured by sample weighing, the corresponding relative humidity is measured by embedded sensors. All three approaches are compared and correlated to each other. The evaluations show only weak correlation and, in several cases, contradicting results. Samples are considered as being ready for layering and not-being ready for layering at the same time, depending on the chosen approach. Due to these contradicting results, a general threshold for the risk of damage cannot be derived based on these measurements. Furthermore, the experiment demonstrates that the measurement of corresponding relative humidity is independent of the considered screed type or screed composition. This makes the humidity measurement to very promising approach for the installation of material moisture monitoring systems in the future.

Electronically Actuated Leveling System for Screeding Concrete

Abstract: An apparatus for leveling a concrete screed having a frame and a screed head secured thereto includes a plurality of vertically adjustable leveling legs driven by a plurality of electrical actuators responsive to a command supplied by a user interface.

Shower floor mud forming device and methodology

Abstract: A shower floor mud forming device includes two rings, at least one section of the big ring, implanted into shower floor mud in desired location and orientation. Device installed without or with the slope guide which ensures correct location and orientation of the rings and section of the big ring. Those elements of the device are functioning as a support for screed tool, which removes/shaves off excess of the floor mud on top of the elements of the device. Correct location and orientation of those elements ensure desired smooth surface and desired slope of the shower floor mud, which ensures correct surface of the finished shower floor. Elements of the device can be reusable or disposable. Slope guide can be used with or without leveling adjusters. Slope guide can be used without or with the pole, which can be used for alternative way to verify level of the top surface of the slope guide.

Screed heating element holder

Abstract: A screed assembly for use with a paving machine. The screed assembly can comprise: a screed plate; a holder configured to be removably connected to the screed plate and configured to be positioned thereon, wherein when connected thereto the screed plate and the holder form a channel having an opening at one end thereof; and a heater assembly having a heating element configured to be received in the channel and to be aligned by the holder when so received relative to an axis of symmetry of the screed plate.

Hygrometric Moisture Measurements Based on Embedded Sensors to Determine the Mass of Moisture in Porous Building Materials and Layered Structures

Abstract: Subfloors are layered structures, consisting largely of porous building materials, such as screed. They are often suffering damage from tap water leakage, which is a typical problem in buildings, and which has largely contributed to repair costs of almost 3 billion Euro in 2018 alone in Germany. In this context, especially mould plays a role, which is both destroying the structure and posing severe health risks.

Modified fine-grained concrete for floor heating system

Abstract: This work shows the influence of components and hardening conditions on linear shrinkage of fine-grain concrete. The floor heating system is one of the most popular options of the heating system these days. The possibility of using this composition for screed for floor heating system is shown. A method of enhancing of strength of the concrete by adding reinforcing fibers and plasticizer has been suggested. Concrete composition has been optimized.

Asphalt screed extension tube adjustment assembly

Abstract: A screed assembly for a paving machine is disclosed including a main screed portion and a screed extension portion being laterally exterior to the main screed portion. Furthermore, a screed extension tube is coupled to a screed frame and a screed extension portion frame, the screed extension tube adjusts a width of the screed extension portion. The screed assembly may further include an extension tube support mechanism having a bushing circumferentially surrounding the screed extension tube and disposed within a bushing recess defined in the screed extension portion frame. The extension tube support mechanism further having a retainer ring that circumferentially surrounds and is in direct contact with at least a portion of the bushing, and the retainer ring is capable of being adjusted between the bushing and the screed extension portion frame to eliminate an uncontrolled movement of the screed extension tube and the screed extension portion.

Device for fastening a screed rail

Abstract: A device for fastening a screed rail relates to finishing work in the field of construction, specifically to devices for installing and adjusting a screed level during plastering. The technical result of the invention is an increase in the functional capabilities of a device for fastening screed rails of various widths. The stated problem is solved in that the device for fastening a screed rail comprises a lower plane, on which a fastening groove is disposed, and an upper plane that is equipped with a mounting platform and grooves for installing a screed rail, wherein the upper plane is equipped with stepped retainers and with diagonal retainers which in turn comprise tongues and guide grooves. The device for fastening a screed rail is also equipped with a fastening opening.

A paver machine and a method for paver screed height calibration

Abstract: A paver machine includes a screed arranged to level out road material disposed on the ground and a pressure actuated screed lifting cylinder arranged to lift and lower the screed with respect to the ground. A pressure sensor is arranged to measure the pressure in the cylinder when the screed is being lifted or lowered. Further a control unit configured to receive pressure data from the pressure sensor indicative of the pressure in the screed lifting cylinder when the screed is being lifted by the screed lifting cylinder. Based on analysing the pressure data, the control unit sets a reference height position for the screed.

Concrete screed power control linkage

Abstract: A power unit is configured for use as part of a concrete screed and includes a frame, a powered drive, and a mechanical control connection. The frame includes a drive housing and a handle to be grasped by a user, with the handle being configured to facilitate manual advancement of the concrete screed in a forward direction. The handle includes a grip and a relatively shiftable user-operated drive controller. The powered drive is operably supported by the drive housing and is configured to rotate a rotatable concrete forming drum.

Road finisher with output adjusters for electrical insert heating devices

Abstract: A road finisher comprises a towing vehicle including a material hopper at a front in a paving travel direction for receiving paving material, and a paving screed which is pulled behind the towing vehicle in the paving travel direction for compacting paving material. A generator for providing electrical power is provided on the towing vehicle. A plurality of electric heating devices is provided on the paving screed for heating the paving screed. The road finisher further comprises a power distribution arrangement having a line network configured to supply the heating devices with power provided by the generator. The power distribution arrangement comprises a plurality of power adjusters provided on the paving screed and each power adjusted is associated with one of the heating devices. The road finisher comprises a control device configured to control the power adjusters to individually dynamically adjust the power supplied to the respectively associated heating device.

Terrace screed device

Abstract: The invention provides a terrace screed device. The terrace screed device is characterized by comprising an H-shaped fixing bracket (1-1) and a screed range pole (2-2); the H-shaped fixing bracket (1-1) serves as a skeleton of the whole terrace screed device and is used for bearing and controlling an elevation; and the screed range pole (2-2) serve as a reference for elevation control and has thefunction of surface layer leveling, a pipe body (4) is placed on a transverse rod (3) of the H-shaped fixing bracket (1-1), a bar body (5) is inserted into the pipe body (4), and the pipe body (4) isin rolling fit with the bar body (5) to reciprocate in the horizontal direction of the transverse rod (3). The device solves the problem that the elevation of the middle part of a large-area terrace cannot be guaranteed, and the large-area terrace is divided into a plurality of areas; and compared with a traditional terrace pouring elevation control method, the method is more accurate, the operation efficiency is higher, and the apparent flatness is more easily guaranteed.

Screed extension for a main screed frame of a paving machine

Abstract: A screed extension for a main screed frame of a paving machine includes an upper frame and a lower frame disposed below the upper frame. A height adjustment system is disposed between, and coupled to, the upper and lower frames. The height adjustment system is configured to moveably couple the lower frame to the upper frame. The height adjustment system includes an upper mounting plate affixed to the upper frame, and a lower mounting plate affixed to the lower frame. The height adjustment system also includes a first tube that is located between and coupled to the upper and lower mounting plates such that a first end of the first tube is configured to establish an interference fit with the upper mounting plate and a second end of the first tube is configured to establish an interference fit with the lower mounting plate.

Concrete pouring anti-cavitation mechanism for building construction

Abstract: The invention discloses a concrete pouring anti-cavitation mechanism for building construction. The concrete pouring anti-cavitation mechanism for building construction includes a fixing frame, an integrated switch and tracks; the integrated switch is installed on the left side surface of the fixing frame; a vibration device is installed on the left side of the fixing frame; a first pressure device is installed inside the left side of the fixing frame, and a first connecting device is connected to the right side of the first pressure device; a second connecting device is connected to the backof the first pressure device; a second pressure device is arranged on the right side of the first pressure device; a storage device is connected to the right side of the second pressure device; and the tracks are fixedly installed at the bottom end of the fixing frame. The concrete pouring anti-cavitation mechanism for building construction is provided with the second pressure device, which is convenient for grid-like concrete poured evenly on the floor; the first pressure device and the second pressure device can be used according to the conditions of the pouring site; the first pressure device and the second pressure device can be used at the same time through the vibration device, which improves the efficiency of pouring concrete; and a screed plate can smooth the concrete on the surface of the steel structure grid.

Non-woven carpet production line

Abstract: The invention relates to a non-woven carpet production line. The production line comprises a workbench, a drying box is arranged on one side of the workbench, a drying assembly is arranged in the drying box, a leveling assembly is arranged on one side of the drying assembly, the leveling assembly comprises two correspondingly arranged screed plates, and cloth abuts between the two screed plates; agluing device for gluing and adhesion between layers of the cloth is arranged at the end, away from the drying box, of the workbench; a cooling device for cooling dried cloth is arranged on the side,away from the workbench, of the drying box; and a static eliminating device for eliminating static of cooled and dried cloth is arranged at a cloth outlet of the cooling device. The production line has the effect of leveling the cloth after the cloth is dried.

Asphalt finisher and management device for road machines

Abstract: An asphalt finisher (100) includes a tractor (1), a hopper (2) provided on a front side of the tractor (1) and configured to receive a pavement material (PV), a conveyor (CV) configured to supply the pavement material (PV) in the hopper (2) to a rear side of the tractor (1), a screw (SC) configured to place and spread the pavement material (PV) supplied by the conveyor (CV) on a rear side of the tractor (1), a screed (3) configured to lay and spread the pavement material (PV) placed and spread by the screw (SC) on a rear side of the screw (SC), and a distance measuring device (51) configured to include a region including a road surface placed and spread by the screed (3), and a planimetric feature (AP) that is used as a reference for a height of the road surface, within a measuring range.

A screed arrangement

Abstract: The present invention relates to a screed arrangement (100, 100') for a paver machine. The screed arrangement (100) comprises a screed body (101) comprising a deflector member (102) and a base plate, and an oscillating tamper bar arrangement (104) positioned between the deflector member (102) and the base plate (106). The screed arrangement further comprises a connecting element (108) connecting the oscillating tamper bar arrangement and the screed body to each other.

Apparatus for Road Pavement using Asphalt Concrete Mixture and Construction Method thereof

Abstract: Facilities for road pavement using an asphalt concrete compound comprise: a screed main body (110); a tamper (120) vertically moved by a predetermined interval and regularly tamping the asphalt concrete compound; a bearing plate (130) pressing the asphalt concrete compound while applying pressure thereto with a self-load; and an auxiliary tamper (140) applying vibration and pressure at the same time, wherein the auxiliary tamper (140) comprises: a hydraulic cylinder (141) attached to a tamping plate (143) to apply the pressure to the asphalt concrete compound at a lower portion; a vibrator (142) attached to the tamping plate (143) to apply the vibration to the asphalt concrete compound at the lower portion; and a tamping plate (143) applying the pressure and the vibration to the asphalt concrete compound at the lower portion, thereby omitting repetitive tamping processes, shortening a construction period, and reducing the emission of CO2.

Engineering road asphalt aggregate laying mechanism

Abstract: The invention discloses an engineering road asphalt aggregate laying mechanism, which comprises a machine body and a screed frame. The screed frame is arranged on the right side of the machine body; asleeve is mounted on the surface of the screed frame; air suction mechanisms are arranged on the two sides of the sleeve; the air suction mechanism is connected with the outer wall surface of the sleeve through a support; a damping mechanism is mounted on one side of the surface of the machine body; a protection box is mounted on the surface of the top of the damping mechanism; and the protectionbox is internally provided with a separation plate. Through mutual cooperation of a draught fan and the gas suction mechanisms, waste gas generated during asphalt pavement can be adsorbed and conveyed to an impurity removal mechanism through a pipeline to be subjected to impurity removal, and then, the waste gas can be filtered through the filtering mechanism, and thus emission of harmful gas inthe waste gas is reduced.

Construction method of gypsum mortar screed strip

Abstract: The invention particularly provides a construction method of a gypsum mortar screed strip The method is characterized in that an operating platform is included, and a standard 2m aluminum alloy ruleris fixed on the operating platform in a vertical placement form in the height direction of a cross section; a 001mm plastic thin film is applied to the upper side of the aluminum alloy ruler in a covered manner; gypsum mortar is uniformly applied to the thin film layer on the upper side of the aluminum alloy ruler; the position of a laser swinger is adjusted according to a plastering control line on the ground; the aluminum alloy ruler covered with the gypsum mortar is pressed on the wall surface in a vertical placement manner, and the aluminum alloy ruler is taken down after the gypsum mortar has certain strength; and the steps are repeated until screeding is ended According to the construction method, flatness and perpendicularity of the screed strip are obtained by primary referenceconstruction of the laser swinger, so that construction period is saved, setting and hardening are just performed for a period of fixed time, and strength of quality control is high