Project Wearing Surface Technoloigy

Wearing Surface TechnologyProject Specifications and testing The penetration test on bitumen : it is a arbitrary measure of hardness it consists of measure of degree of penetration in tenths of a millimeter of a standard needle and weight weighing 100g into a sample of bitumen maintained at 25C 180/200 means must penetrate within the range of 180 to 200 tenths of a millimeter. Test method ASTM D5

Penetration test apparatusTest for viscosity at 60C : normally done with a U tube viscometer a head of bitumen is formed on one side of the tube conditioned in a constant temperature bath and time taken it to flow under the force of gravity between two calibrated marks is proportional to its viscosity. Usually tests are done at 60C , Test method is ASTM D2171

Viscosity testing apparatus

Flash point test: this test is to ensure that during normal temperature range the danger of catching fire is reduced, test is done by a sample of bitumen is heated at a specified rate in an open steel container a small flame is passed over the cup and temperature at which a flah of flame envelopes the surface is defined as the flash point.Test method ASTM D92

Flash point apparatusRolling thin film test (RTFO test) is designed to simulate the hardening that occurs during the hot mixing process. Test method ASTM D2872

RTFO TEST APPARATUS

TEST CYLINDERSSolubility of bitumen in trichloroethylene is a test to determine the presence of contamination such as mineral matter or carbon, Test method ASTM D2042

BITUMEN DISSOLVED IN TRICLOROETHYLENEKinematic Viscosity mm2/s at 135CThe kinematic viscosity characterizes flow behavior. The method is used to determine the consistency of bitumen as one element in establishing the uniformity of shipments or sources of supply. Test method ASTM D2170

KINEMATIC VISOCITY TESTING APPARATUSDuctility test on BitumenThis test method provides one measure of tensile properties of bituminous materials and may be used to measure ductility for specification requirements. at 25C, test method ASTM D113

DUCTILITY TESTING APPARATUS Tests done on aggregateSOURCE PROPERTIESCrushing Resistance: this test shows the chances of breakdown of aggregates. the test consists of loading a sample of aggregate in the range of 13.2 to 9.5 mm in nominal 250mm diameter cylinder in which it is broken down to the extent that 10 % of the resultant material passes through a 2.36mm sieve , test method NZS 4407 test 3.10

CRUSHING RESISTANCE TESTING CYLINDER

Weathering Resistance: this test is to measure the resistance to breakdown of aggregate when exposed to wetting, drying heating and cooling. The test consist of sealing chip getting subjected to heat, cold wetting , drying and rolling the degree of breakdown is assessed by change in percentage of material passing a 4.75 mm sieve , test method NZS 4407 test 3.11Weak particle test: the Australian weak particle test (AS 1141.32-1995) has been introduced in M/6 2002 to measure the percentage of unsound particles. The aggregate shall have a maximum of 1% of unsound materials. Polished Stone Value: this is measured to show the resistance of the material against polishing; the chips lose their rough microtexture by repetitive action of the traffic, NZTA M/6 specifies the procedure for determining of polished stone value BS EN 1097 Part B

PRODUCTION PROPERTIES

Sand equivalent & clay index: These values represent the amount of fineness and character of clay like material coating on coarse aggregate. T est method NZS4407 test 3.6, 3.5

SAND & CLAY EQUVALENT TESTING APPARATUS

1) Size and Shape: larger sizes are tested for size and shape by physically measuring a sample approximately 100 stones for average least dimension (ALD) and average greater dimension (AGD). With smaller stones the size is controlled by sieve analysis test test method NZS 4407 test 3.13Average least dimension (ALD): it is obtained by using a dial gauge, approximately 100 chips are recorded and average calculated

AGD apparatusALD apparatus

Average greatest dimension: is obtained by placing the chips in a graduated trough aligned in their greatest dimension and by dividing the total length of the trough by the number of chips the AGD is obtained

Single and double broken faces: this test is done to find the amount of broken faces of the aggregates which is done manually by inspecting each aggregate with human eye, test method NZS 4407 test 31.4 Los angles abrasion test: is a common test method used to indicate aggregate toughness and abrasion characteristics. Aggregate abrasion characteristics are important because the constituent aggregate in HMA must resist crushing, degradation and disintegration in order to produce a high quality HMA. test method NZS 4407 test 3.12It is done by putting aggregates and specified of steel balls in a drum and rotating it for specified time and speed , the percentage of material broken down to less than passing 1.7mm sieve is termed as loss and given as LA abrasion test value

L A ABRASION TEST MACHINEAGREGATE BEFORE AND AFTER

Wet/Dry Strength Variation: the wet and dry are determined by using AS 2758 Part 5 Values are reported and used in contract

Wet/Dry strength test equipment and compression machine

Water Absorption: the test is done in accordance with AS 1141 or ASTM C127 the resulting value is reported and used in the contract documents The water absorption is of particular concern for the asphalt and must be kept constant, an increase in water absorption will likely lead to the increase need for the binder in asphalt mix a thus increasing the cost of asphalt mix. The water absorption affects the value of effective bitumen in the asphalt mix.

Aggregate Grading: Grading is an important factor when considering asphalt it shows how well the material could be compacted to a layer and what are the maximum and minimum particle sizes and its percentage composition. Grading has a profound affect on material performance and various grading include open , dense, gap graded asphaltic mix grading test is usually done by passing a known weight of aggregates through sieves of getting progressively smaller , and mass of aggregates retained is weighed.

TESTS DONE ON THE PAVEMENTSkid resistance: skid resistance is the resistance to skidding the value is of particular importance while when wet conditions are prevailing , prime cause of reduction in skid resistance is the decrease of the microtexture, when microtexture becomes very less and the location of the pavement is at a accident prone area and if the project is economical then it is likely to be resurfaced. This is done on existing pavement surfaceThe most commonly used techniques are British pendulum it gives only reading for a specific small area but still widely used it is used to measure the skid resistance and give value of a small region in question

BRITISH PENDULUM

SCRIM, Sideways Force Coefficient Routine Investigation MachineThe scrim runs at about 50 kmph and wets the surface ti has water tank in build in it measures the skid resistance with the help of a wheel which is orient at angle of 20 to the vehicle the force that pushes the wheel into the straight direction is directly proportional to the skid resistance an that value is measured. This is done on existing pavement surface

Grip testerThe braking effect of the third wheel on the axle is measured which is connected by a pair of gears is measured and is directly proportional to the skid resistance. This is done on existing pavement surface

Road, Pavement Friction Tester (PFT)Same as that of the grip tester instead here a wheel is locked and the friction between the wheel and the pavement is measured. This is done on existing pavement surface

Macro texture testing (sand circle method)This is primarily done with sand circle test: in a sand circle test is done to get the macro texture parameter of the pavement, in which sand of specified well rounded grains are spread across the pavement and using a straight edge it is spread the larger the diameter the lesser the texture depth and vice versa the procedure is given in TNZ T/3 standard. This is done on existing pavement surface

Falling weight deflectometerA falling weight deflectometer (FWD) is a testing device used to evaluate the physical properties of pavement. FWD data is primarily used to estimate pavement structural capacity for 1) overlay design and 2) to determine if a pavement is being overloaded. The machine is usually contained within a trailer that can be either towed to a location by another vehicle or, when used on railway tracks, placed on a hand trolley and pushed to the location; it is used to find the properties of existing pavement.

Roughness RequirementsIt is recommended that no 100 m moving average of lane roughness over the extent of works shall exceed a maximum of 70 NAASRA counts/km, with the target value being 60 NAASRA counts/km.

Scala penetrometerUses blows to measure the CBR of the pavement or representative subgrade it measures the penetration and number of blows to calculate the representative CBR of the existing pavement.

Benkelman Beam Used for the determination of the rebound deflection of a pavement under a standard wheel load and tyre pressure, with or without temperature measurements used on existing pavement to find out the CBR through back calculations .

Nuclear densometerThese tests are used to find the compaction of the asphalt laid after compaction, Locations for testing shall be selected using ASTM D5361

Coring and testing density and dimensions of asphaltCore air voids are calculated from the core Bulk Specific Gravity (relative density) and the Maximum Theoretical Specific Gravity (relative density) using ASTM D3203

Temperature measurementTemperature is measured constantly during the paving of asphalt as the workability depends on it is done using a temperature gauge

Tests done on for getting modulus of asphalt Indirect tensile test :indirect tensile strength is determined by measuring the vertical diametric load at failure as well as horizontal change in diameter and this is converted to indirect tensile strength from which modulus is calculated from indirect strength vs. diametrical strain relationship

Flexural beam test: this test is used to find the fatigue characteristics and the flexural stiffness of the material (modulus) using appropriate formulas

Development of specifications and test methods for pavements in New ZealandThe New Zealand has moved on to a performance based specifications this make the contractors more competitive and more innovate in their field, now the contractors can find alternative materials to suit the requirements of the pavement provided they met certain performance criteria being durability and rut resistance and accepted a 12 month warranty/maintenance period for the final constructed pavement. For example specifications like TNZ B/3 Performance Based Specification for Structural Design and Construction of Flexible Unbound Pavements& TNZ M/22 Guidelines for the Evaluation of Unbound Road Base and Sub-base Aggregates lays emphasis to test the new material whether it conforms with the requirement or not for e.g. the RLT (Repeat Load Triaxial Test) a new standard NZTA T15 (Repeated Load Triaxial (RLT) Testing for Pavement Materials) The aim is to enable those aggregates that do not meet NZTA M/4 requirements to be used in place of premium aggregates (NZTA M/4) on low volume roads, To reduce the risk of early pavement failure by only using those aggregates on high trafficked road, Allow the use of modified/chemically-stabilised aggregates as a means of utilising good quality aggregates that are moisture sensitive when unmodified in high trafficked areas. There is increased emphasis on the skid resistance policy in New Zealand NZTA T10 (specification for state highway skid resistance management) and PSV measurement is importantWe can see that a number of new tests are introduced have been introduced in order to explore alternative means of assessing aggregate quality for e.g. TNZ P/23 performance based specification of hot mix asphalt wearing course surfacing

References

NZTA. (2011). Bitumen testing. Retrieved from http://nzta.govt.nz/resources/bitumen-testing/docs/bitumen-testing-tm-6003-v2.pdfNZTA. (2011). Roading Bitumens. Retrieved from http://www.nzta.govt.nz/resources/roading-bitumens/docs/roading-bitumens.pdf

NZTA (2011). Performance test for roading aggregate and alternative material. Retrieved from http://www.nzta.govt.nz/resources/research/reports/335/docs/335.pdfCCCA Australia. (2009). coarse asphalt requirement. Retrieved from http://www.ccaa.com.au/imis_prod/documents/Library%20Documents/Tech%20Note%2071%20Course%20Asphalt%20LR.pdfPavement interactive. (2015). broken faces of aggregates. Retrieved from http://www.pavementinteractive.org/search-results/?cx=partner-pub- 2893&cof=FORID%3A10&ie=UTF-8&q=broken+faces&x=0&y=0Highway maintenance.com. (2000). skid resistance. Retrieved from http://www.highwaysmaintenance.com/skidtext.htm

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