GB2394061A

GB2394061A - Testing road surface materials

Info

Publication number: GB2394061A
Application number: GB0213323A
Authority: GB
Inventors: Nageim Dr H Al
Original assignee: Liverpool John Moores Univ
Current assignee: Liverpool John Moores Univ
Priority date: 2002-06-11
Filing date: 2002-06-11
Publication date: 2004-04-14
Also published as: GB0213323D0

Abstract

A sample 2 of road surface material (e.g. bituminous of concrete material) is engaged by wheels 1 which are moved against the material to test its properties. The wheels may be loaded against the sample 2. The wheels may be moved by an endless chain 3 driven by sprockets. Tracks may be used instead of wheels. The apparatus can test wear, crack generation, rutting, noise and skid resistance of the road surface and its interaction with particular tyres.

Description

239406 1

LIVERPOOL MATERIAL TESTER (HAN 2002) AND METHOD OF MAKING

THE SAME

Technical field

This invention relates to a freely rotating loading device moving horizontally (or with any pre-programmed angle to the horizontal and / or vertical axes) at varying speeds. The new device is designed to measure and quantify the changes in material properties and or structural properties. This includes responses to applied loads under different loading and environmental conditions. It can be also be used to quantify the deformation characteristics of bound and / or unbound materials e.g. flexible bituminous mixtures or layers; and rigid pavement materials such as concrete pavement.

The proposed device is actually dual purpose insofar as it is able to assess the characteristics and responses of the moving loading mechanism and its interaction with different mediums e.g. rubber tyres on road surfaces, railway carriage wheels on rails, caterpillar tracks or PR 751 equipment with a heavy duty conventional undercarriage used for Hydrostatic Crawler Tractors carrying its own weight or a specific load. The device can also be used to measure and quantify material or structural properties under different environmental conditions / mediums e.g. at varying temperatures; the presence of surface water / fluids, solids or dust (with or without hard small materials) on the moving device and the materials / layers being tested.

Specific applications is to measure the responses of the device and or the supporting surface/materials to: À The variation of the applied load(s) including dynamic (constant and /or varying) in applied magnitude.

The variation in the Loading time and vehicle speed.

À Wheel dimensions and diameters.

À Rubber wheels (treaded, treadless, solid and pneumatic); metal wheels; composite material wheels, plastic wheels etc. À Supporting mechanisms or structures.

À Sample and / or layers dimensions and properties À To measure and quantify the amount of change in wheel / surface interface noise, tearing, rutting and deformations due to variations in the action and or amount of load applied (including repeated loading to simulate traffic effects), providing results that accurately represent field

conditions. To identify, via the resultant interaction between the device and tested material responses to faults in the surface textures of the materials tested.

The application is concerned with potential modifying the new equipment to improve its testing and construction materials characteristics.

Background

Liverpool material and structural testing device, HAN, 2002 is a new testing equipment, it can be housed (if required) in an insulated controlled environmental cabinet, for example environmental chamber, heated or cooled room or insulated heated or cooled cabinet. Temperature range can vary from very low to high temperature depends on the testing criteria, for example temperature can vary from less than - 50 degree C to more than 1500 C .

A Wheel, single (or more than one wheel) travel horizontally, circle (or at any angle) on insitu structure or on the sample or samples to be tested in the laboratory or any desired location. The loaded or unloaded wheel, track or belt can be single, dual, or of any numbers as specified by the user. The device can be loaded with any specified load(s) or carry its own weight.

The interaction between the wheel(s), track(s) or belt(s) with the sample(s) can be measured in terms of material wearing, rutting, noise generated from tyre, wheel, track road surface interaction and conditions, skid resistance, vehicle breaking distance at different tyre and road surface conditions, water/liquid spray in wet conditions, etc. (as in the case in testing road pavement structure). The wheel, track or belt also can be used to test strength properties of the samples and structural layers under the action of the load, for example the fatigue strength, cracks generation, de-bonding, deflections, etc of road surface, of pavement surface, of structural surfacers material surfacers, element surfaces, railway track system both the conventional and new railways track systems.

The influence of the wheel, track or belt loaded or unloaded on the sample is measured by using conventional measuring equipment's such as transducer, signals from which are transmitted to the computer system(s), etc. The short or long term's changes in material mechanical strength properties and durability under the action of real loading and environmental conditions, to which they are subjected during their useful design life, are the utmost importance for their application. AS the main function of a structural element or a structural system is the distribution of the load(s) of loads actions to the other supporting system or to the foundation.

To gain a clear insight into the change in the properties of the material any testing equipment and method that do not stimulate the use of such material in their real application environments will lead to incomplete information from which the investigator reach unreliable conclusions.

ASP A.; design engineer has to base his work on the conclusions that drawn

from the experimental work, it is clear that the design of any material subjected to moving wheells, track, or belVs can only be improved when the moving wheel/s, track/s, or belVs load(s) islare applied in real environmental and loading conditions.

The current practice (for example in road and airfields pavement construction

industry) is to use road wheels testing facility such as;

Ulster Load Tyre Road Assimilator( ULTRA). It is made of varying speed drum. The load is applied through a tyre which is smooth and the pressure and loading were kept constant through out the measurements. The tyre is not moving horizontally as the case in the tyres of a real vehicle moving on a road surface. Also the speed range is limited.

Wheel Tracker such as Wessex Wheel Tracker S867, or Hooper Ltd. Wheel Tracker). The machine is designed to carry out tests on asphalt samples in according to BS 598. A sample travels horizontally on a reciprocating table under a freely rotating rubber tyred wheel. Penetration of the wheel produces a rut, the depth of which is measured and recorded by a purpose built computer program. The wheel diameter is in the range of 200mm to 205mm and 49mm to 51 mm wide. The rubber thickness is about 10- 13mm Treadles. Load is in the range of 515 to 525 N. sample size is around 305mmx 305 mm with standard thickness of 35mm to 55 mm. The wheel speed is 10 to 30 RPM and travel 230mm( simple harmonic Motion) Repeated Load axial Test( ALA). Is an unconfined uniaxial test used in many countries to quantify the permanent deformation characteristics of bituminous paving material. It includes repeated load loading to simulate traffic effects. It does not provide results that accurately represent field

conditions. Finally, a paper has been published on research to quantify the permanent deformation characteristics of bituminous pavement structures using full-scale trial road sections. The materials subjected to traffic loaded wheel tyre travel in a circular way/ path with varying diameter and speed. The research results concluded that circular motion of the wheel on the sample causes a stress distribution within the material different than those caused by the real horizontal movement of traffic vehicle on road surface. It is not practical, as the diameter of the circle is very large and not practical to be used in laboratory environment.

It would be desirable therefore if a way could be found to build a load wheel/s, track/e or belVs assimilator so that it could be used satisfactory for testing any material or a structure subject to a loaded and un-loaded moving lyre/wheel, track chains or belt(s) moving on the material surface at a speed, loading and environmental conditions similar to those in real traffic environment.

The tracking wheel, tyre, track chains or belt: materials, size and properties. The range of tracking wheel/lyre, chains or belts include all those available wheels, high duty, solid metal wheels such as the railways track wheels, pneumatic rubber tyres or equivalent materials used to manufacture conventional tyres for conventional traffic road vehicles such as cars, lorries or air plains. Rubber tyres with dimensions and thickness varying as necessary, or with solid rubber, metal/other materials may be composite as per manufacture specifications. Alteratively any wheel with a high duty rubber/

metal/composite material tyre, with wheel diameter of 3mm to 1000mm or any other practical diameter ranges. The width of the tyres may range from <1mm

to 2000mm or any other practical dimensions depend on the user specifications. The material of the wheel can be of any practical thickness or

the specified thickness to be tested.

The size of the wheel is within the today's practical ranges for conventional wheels, tyres, track chains and belts.

The material to be tested includes any material in the market, which is considered suitable, to curry the wheel, track chains and or belt loads. The surface on which the moving loads is placed may contains, composite materials, or made from a structure(s) which is made from one layer or multy-

layers, each layer contains the same materials with the same thickness or each layer made from different material and or having different properties including their thickness.

Example. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1. Shows in respective, the freely rotating wheel/lyres testing equipment. The Load wheel assimilator, consist of a loaded wheel(s) (1) which bears on a test specimen(s) (2) or on insitu material and or structure/s.

The wheel is driven by Wheel Chain Arrangement (3) which may be driven by a drive motor using " A Velt drive (4), see figurer or any other suitable mechanisms. The specimen held on a table or reciprocating table (5), The table can be stationary or moves forward and backwards under the wheel or wheels (loaded and or unloaded). Mounting table (optional)(6) for the purpose of holding the specimen or levelling the surface of the test specimen (with the desired angle reference to the horizontal reference line) and assembling the base plate and clamping blocks around it. Weighted cantilever arm (7) can be used to apply the standard load or the loads may be applied using springs. Slide shaft and damper (8) oil type or any other suitable type can be used to support the load applied (9) make sure the sample is maintains in the desired testing angle with reference axis. And devices to; À monitors the rate at which wheel-track deformation develops in the surface of the specimen or the insitu materials.

À Monitor the noise generated due to the interaction between the loaded wheel tyre (solid, treaded, treadles, pneumatic with certain tyre pressure, etc.) Monitor the water and or liquid spray depending on the interaction between the wheel and the tested materials/surface(s), which depends in turn on many factors among them the environmental factors, loading characteristics, wheel specification, tyre specifications, speed of the

moving traffics or tyres and specimen surface properties and characteristics. Monitor the change specimen surface textures due to testing under different environmental, loading and traffics conditions.

Monitor the durability and temperature change due to the factors mentioned above or under controlled temperature andtraffc loading condition including vehicle breaking and stop conditions.

it

Claims

À Monitor the internal change in the macro and microstructure of the surface of the materials or the materials from which the sample or the structure is made. À monitor other changes in the properties of the tested material or the testing wheel and or tyre. Claims

1. A particulate loading device (freely rotating; wheel, tyre, track or belt), consisting of a loaded or unloaded, single or multiple; wheel, tyre, track and or belt / tyre that bears on a test specimen(s) or surface(s) whereby the wheel / tyre moves forward on the test specimen(s) or surface(s) (that is stationary or moving at a particular speed) at any practical given speed within the practical speed range of a moving traffic vehicles e.g. the speed of light weight cars, lorries, racing cars, trains or aeroplanes using a runway etc.

2. A particulate loading device as claimed in claim 1, consisting of a loaded or unloaded single wheel fitted with a tyre or multi wheeled fitted with tyres, that bear on a test specimen(s) or surface(s) whereby the tyres move forward on the specimen(s) or surface(s) at any practical given speed within the practical speed range of a moving traffic vehicles e.g. lightweight cars, lorries, racing cars, train or aeroplanes using a runway etc.

3. A particulate loading device as claimed in claim 1 and 2, consisting of a loaded or unloaded single wheel fitted with solid tyre.The outside diameter of the tyre = 10mm and fitted to the wheel. The tyre can be of rectangular section or of tyre shape section with width ≥10mm, treaded or treadless with 3mm to 200 mm thickness or any desired thickness above or below the these figures. The tyre also can be of a solid rubber with any specified hardness in accordance with BS 903-A57 or made from any materials of any other practical specifications.

4. A particulate wheel / lyre-loading device as claimed in claim 1, 2 and 3 consisting of a loaded or unloaded single wheel fitted with a pneumatic tyre or a tyre filled with air, gas, or liquid. The tyre of outside diameter = 10mm and fitted to the wheel. The tyre can be of rectangular section or of any desired tyre shape section, with width ≥ 10mm treaded or treadless with any practical thickness, preferably the thickness range from 3mm to 200 mm. The tyre can be of rubber with any specified hardness or any other materials in accordance with the current practical specifications.

5. A particulate wheel / tyre loading device, as claimed in claim 1, 2 and 3, consisting of a loaded or unloaded single wheel or multi-wheeled which bears on a test specimen(s) or surface(s) held on a table. The table moves to and for beneath the freely moving wheel at a specified speed and whereby the wheel or multi-wheels move forward on the specimen at any practical speed within the practical range of a moving traffic vehicles or

other moving devices e.g. lightweight cars, lorries, racing cars, trains or aeroplanes using a run way etc.

6. A particulate loading device rotating freely, which bears on a test specimen or surface, wherein the device comprises of a moving wheel on loaded or unloaded belt(s) or truck chains e.g. the PR 751 standard equipped with a heavy duty conventional undercarriage used for Hydrostatic Crawler Tractor. Whereby the belt(s) or truck chains move forward at any practical speed on: a specimen(s), surface(s), structure(s), structural element(s) or layer(s) and or / on materials wherein the speed of the loaded belt or truck chains is within the practical speed ranges of moving traffic e.g. Crawler Tractor and / or tanks.

7. A particulate free rotating wheel loading device as claimed in claims 1, 2, 3 and 4, whereby the wheel made from metal, plastic or composite materials, and wherein the wheel is made from solid materials e.g. zinc plated riveted steel etc or the wheel is made hollow. The wheel fined (or not) with tyre, with the tyre as described in previous claims.

8. A particulate moving wheel, belt or track chains loading device as claimed in the previous claims, wherein the loaded device moves horizontally and / or with any specified angle to the horizontal axes of the tested specimens and or surface(s), whereby the device applies its own weight or specified loads to the specimen(s), structure(s), element(s) , or any specified structure / material surface(s).

9. A particulate moving wheel, belt or track chains loading device as claimed in all of the above claims used to test materials, surface structures or elements; to measure and quantify the change in the material(s), structural properties and responses to the applied loads in different loading and environmental conditions e.g. different temperatures, wind, humidity, material stiffness etc.

10.A particulate moving wheel, belt or track chains loading device as claimed in the previous claims for testing materials, surfaces, structures, structural layers or elements to quantify the elastic and permanent properties and deformation characteristics of such supporting materials under the applied moving loads e.g. the permanent or elastic, visco elastic and plastic deformation of flexible pavements (bounded materials e.g. bituminous mixtures for roads and airports pavement(s), rigid pavement materials etc. This includes the material from which the wheel is made /or those martial(s) and / or structure(s) which carry the moving iced device (loaded or unloaded) due to the interaction between the moving and loaded device such as loaded wheel(s), belts or truck chain(s) e.g. the PR 751 standard equipped with a heavy duty conventional undercarriage used for Hydrostatic Crawler Tractor carrying its own weight or a load(s) and the supporting mechanism.

11.A particulate moving wheel, belt or track chains loading device as claimed in the previous claims for testing materials, surfaces, structures, structural

layers or elements to measure / quantify the effect of; (i) the load(s) including dynamic, constant and /or varying in applied magnitude (ii) speed (iii) wheel and or tyre dimension and surface characteristics; including width diameters, the materials from which the wheel and or the tyre are made and the surface roughness (iv) rubber tyre wheel, solid, treadles, treaded, pneumatic filled with air, gas or liquids, etc. (v) supporting mechanisms or structure, type and conditions (vi) sample and or layer(s) dimensions and properties in different loading and environmental conditions (e.g. varying temperatures, the presence of surface water on the wheel, tyre; and on road, moving belt or track chains) on the tested materials.

12.A particulate moving wheel, belt or track chains loading device as claimed in the previous claims for applying moving loads and measure and quantify the amount and or the change in; the wheel / surface interface properties, noise, wearing and roughness etc due to variations in: (i) the action and / or the amount of the load (ii) the contact surface due to the surface textures of the tested surface / materials of the texture of the wheel, tyre, belt and or the track chains and fault(s) in the mechanisms through which the load(s) is / are applied (iii) repeated loading to simulate traffic effects and provide results that accurately represent field conditions.

13.A method of modifying such new equipment(s) to improve its characteristics and usefulness in testing; and contribution to improving material, structure, structural element(s) and surface and or surfaces subjected to moving wheel or wheels, road traffic or aeroplanes etc.