AU743067B2 - Cold-mix asphalt - Google Patents

Description

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AUSTRALIA

Patents Act 1990 PATENT REQUEST: STANDARD PATENT AUSTRALIAN COLD-MIX ASPHALT SAMKLRST NO. 20 PTY LTD PO BOX 567 COLLINS STREET, MELBOURNE VIC 3000 ("the Applicant") The invention is described in the following statement: IP Australia

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BatchNo: 72-S7' COLD-MIX ASPHALT THIS INVENTION relates to a material for: road surfacing and construction of pavement courses; road maintenance and repairs; and stabilisation of base/sub-base courses.

This invention relates particularly to the surfacing and construction of roads, but it is to be appreciated that it also extends to other surfaces over which pedestrians or vehicles travel, eg sidewalks, pavements, pedestrian paths, sports fields, bicycle tracks, parking lots, aircraft landing strips and airports, bridge decks and the like.

Composition and Characteristics According to a first aspect of this invention there is provided a material for laying a traffic bearing surface and/or underlaying courses including: a particulate carbonaceous material in intimate admixture with bitumen emulsion; a particulate cementitious material including cement, silica fume, ground granulated blast furnace slag or a powdery residue of coal combustion, especially the combustion of pulverised fuel (such as black coal) in power stations ("fly ash"); and Sthe mixture of the carbonaceous material, the cementitious material and bitumen emulsion.

Thus in use, particulate carbonaceous material and particulate cementitious material are admixed with binder yielding material which when exposed to the atmosphere, sets and hardens, providing a stable road surface.

Preferably, the material includes particulate stone intimately mixed with the said mixture of carbonaceous material, cementitious material and bitumen emulsion.

Preferably, said bitumen emulsion is anionic bitumen emulsion.

In a preferred form the material comprises 35% 45% by weight of carbonaceous raw material, 1% 20% by weight cementitious material, 37% 45% by weight particulate stone and 5% 8 by weight bitumen emulsion.

Preferably, said carbonaceous material has a particle size of 0.5mm 9mm.

Preferably, said cementitious material is fly ash which results from black coal combustion and has a particle size of 0. Imicrons 0. 1mm.

Preferably, said particulate stone has a particle size of 0.5mm Preferably, the particulate stone is basaltic.

Method of Application According to a second aspect of this invention there is provided a method of laying a traffic bearing surface and/or underlaying courses, including the steps of: intimately mixing carbonaceous material and cementitious material with a bitumen emulsion; and applying the mixture of carbonaceous material and cementitious material with a bitumen emulsion onto a substrate which in use is or may be traversed by traffic, the mixture hardening and setting upon exposure to air to form a traffic bearing surface.

Preferably the method includes the additional steps of compacting the mixture after its application to the substrate.

Preferably the method includes sprinkling water onto the mixture and onto the substrate as it is being applied to the substrate.

Preferably a further component particulate stone is intimately mixed with said carbonaceous material and said cementitious material with said bitumen emulsion in said mixing step.

Preferably said bitumen emulsion is anionic bitumen emulsion.

In use the inclusion of stone enhances the strength of the road surface. Further, the larger the stone particles, the harder is the resultant road surface. An optimum stone particle size is required to ensure optimum binding within the mixture.

In use, the admixed material sets on exposure to air, and more particularly the oxygen therein. If the material is isolated from the atmosphere eg by being sealed in a sealed container, it does not set and harden. Thus it is not necessary to transport the material at high temperatures to avoid the setting thereof. The material may be admixed at source and transported at ambient temperature to its site of usage.

Consequently, it is not necessary to establish capital intensive infrastructure to either admix the components of the material at the site of usage or to transport the admixed material at elevated temperatures from the source to the site of usage.

The presence in the said mixture of the cementitious material significantly improves the hardness of the resultant material and renders it water resistant.

Two embodiments of the invention will now be described in detail below.

EXAMPLE 1 e. In this example 5kg of anthracite coal was mixed with 5kg of particulate basaltic stone and 0.2kg of fly ash and 1.2kgofbituminous emulsion. A minimal amount of water was added to improve the workability of the mix.

o The air dried anthracite coal had a chemical analysis of 9.3% max. by mass of ash, max. by mass of inherent moisture, 23.5% max. by mass of volatiles and 61.1% max. by mass of carbon.

The anthracite coal was sourced from Appin Mine, located 30km north-west of Wollongong, New South Wales. The anthracite particle size fell within the range of 0.15mm 6.7mm. The anthracite had the following particle size analysis: SIEVE SIZE PASSING

TOLERANCE

67 100 4.75 83 2.36 51 1.18 25 +3% 0.6 11 0.3 4 +1% 0.15 1 0.075 The basaltic stone was obtained from CSR Werribee Quarry, Victoria. The stone general particle size generally fell within the range 0.075mm 9.5mm. The basaltic stone had the following particle size analysis: SIEVE (mm) TYPICAL GRADING PASSING 100 6.7 4.75 56 2.36 1.18 0.60 0.425 0.30 0.15 0.075 The fly ash known as Kaolite HPA was obtained from Pozzolanic Enterprises Pty Ltd, 465 Lorimer Street, Port Melbourne, Victoria. The fly ash average particle size fell within the range of 0.01mm 0.015mm and had the following chemical composition: The binder was an anionic bitumen emulsion ASS Anionic Emulsion (slow set grade) manufactured by CSR Emoleum and supplied by Emulsion Manufacturing Plant, 233 Arden Street, North Melbourne 3051. The emulsion is slow breaking with sufficient stability for all purpose mixing. The emulsion has a binder content of approximately The properties of the emulsion are summarised in the table below: CSR EMOLEUM SUBSTANCE BY WEIGHT Bitumen (Petroleum) 30% Oxidised Bitumen 20% Soap Emulsifier 1% Kerosene 1% Water Approximately PHYSICAL AND CHEMICAL PROPERTIES Relative Density 1.lkN/m 3 Boiling Point 100°C Flashpoint 150°C Viscosity not established Colour Dark brown The components making up the material were admixed with each other at room temperature.

Two lkg samples of the material were submitted within twelve (12) hours of preparation to Astec Pty.Ltd, Dana Court, Dandenong a NATA registered laboratory in a sealed container.

The laboratory subjected the samples to the following tests: Determination of stability and flow by Marshall procedure(AS 2891.5).

The procedure was modified to suit industry-accepted procedures for cold asphalt mixes and to enable a comparison to be made with the results of tests carried out in South Africa on products of broadly similar nature.

Note: the only applicable tests required by AS 4283 (Cold Mix Asphalt for Maintenance and Patching) are binder content and aggregate grading.

The results of the tests carried out by the laboratory were as follows: go Sample description: 7mm slow setting bitumen emulsion cold mix with added cementitious material and carbonaceous material.

Sample No.: 1 2 Average Compactive effort: 50 blows (hand) 50 blows (hand) 50 blows (hand) Curing period at 25 C after compaction in days: 3 7 Stability 12.3 25.1 18.7 Flow 6. 1 4.5 5.3 The properties of both samples were determined without the specified conditioning period in a water bath at 60 C for 30 to 40 minutes, prior to testing.

The admixed material does not set provided that it is placed in a sealed environment.

The material starts setting on being exposed to the atmosphere and typically takes less than 24 hours to set. Without being bound by theory, the Applicant believes that the binder is oxidised by 02 in the air and, therefore, by sealing off the admixed material, the binder is prevented from setting. Further without being bound by theory, the Applicant believes that the binder undergoes a chemical reaction with the anthracite and the cementitious material (in the case of the above samples, fly ash) and this is what makes the material bind together. In particular, the Applicant believes that the setting and hardening of the material is greatly enhanced by the reaction between the chemical components of the cementitious material (in the case of the above samples, fly ash) (CaO, SiO 2 A1 2 0 3 Fe 2 0 3 in particular) and the water content of the binder as well as moisture in the anthracite and stone or added water (if any).

The test results indicate an increase in strength of up to 100% when compared with South African results or comparable results available for conventional bituminous cold asphalt mixes.

Observations of samples conditioned in a water bath prior to testing confirmed that the bitumen binder was positively bound with other mix components. Unlike with similar cold asphalt mixes, no leaching of the binder into the bath water was observed.

The Applicant believes that the long term physical properties of the mix are greatly enhanced by inclusion of the cementitious material (fly ash) in the mixture.

Kaolite HPA was obtained from Pozzolanic Enterprises Pty Ltd, 465 Lorimer Street, Port Melbourne, Victoria. The fly ash particle size fell within the range of 0.01mm 0.1mm and had the following chemical composition: Property Result AS 3582.1 Test Requirement Method Moisture Content 0.1 1.0 max AS 35832 Loss on Ignition 0.3 4.0 max AS 3583.3 Fineness 93.0 75.0 min AS 3583.1 Sulfuric Anhydride 0.2 3.0 max AS 3583.8 Magnesia 1.3 AS 3583.9 Relative Water 87 AS 3583.6 Requirement Relative Strength 120 105 min AS 3583.6 SiO 2 48.5 A1 2 0 3 31.1 3 11.5 CaO TiO 2 1.9

K

2 0 0.3 Available Alkali 0.25 AS Na2O 3583.12 Source: Pozzolanic Enterprises Pty Ltd EXAMPLE 2 The same components as those described in Example 1 above were used in making up the material and were admixed with each other at room temperature.

The material was then placed in a sealed container and transferred to the site of usage.

The material was used to repair holes in a heavily trafficked secondary road (East Bentleigh, Melbourne), the material taking less than 24 hours to set, on exposure to the atmosphere. The material was found to have acceptable strength and wear properties, showing no signs of cracking or failure after two months of use.

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Claims (13)

1. A material for laying a traffic bearing surface and/or underlaying courses including: a particulate carbonaceous material and a particulate cementitious material in intimate admixture with bitumen emulsion; the mixture of particulate carbonaceous material and particulate cementitious material and bitumen emulsion setting and hardening on exposure to air to form a traffic bearing surface. 00 o• A material according to Claim 1, including particulate stone intimately mixed with said mixture of particulate carbonaceous material and particulate cementitious material and bitumen emulsion.

3. A material according to Claim 1 or Claim 2, wherein said bitumen emulsion is anionic bitumen emulsion.

4. A material according to Claim 3, wherein 40% 80% by weight is particulate carbonaceous material, 1% 10% by weight is particulate cementitious material, 15% -60% by weight is particulate stone and 6% 15% by weight is bitumen emulsion.

5. A material according to any one of the preceding Claims, wherein said particulate carbonaceous material has a particle size of 0.5mm

6. A material according to any one of the preceding Claims, wherein said particulate cementitious material has a particle size of 0.01mm lmm.

7. A material according to any one of the preceding Claims, wherein said particulate stone has a particle size of 0.5mm

8. A material according to any one of the preceding Claims, wherein the particulate stone is basaltic.

9. A method of laying a traffic bearing surface and/or underlaying courses, including the steps of: intimately mixing particulate carbonaceous material with particulate cementitious material and bitumen emulsion and; applying the admixture of the particulate carbonaceous material and particulate cementitious material and bitumen emulsion onto a substrate which in use is traversed by traffic, the mixture hardening and setting on exposure to air to form a traffic bearing course. A method according to Claim 9, including the additional step of compacting the mixture after its application to the substrate.

11. A method according to Claim 9 or Claim 10, including sprinkling water onto the mixture as it is being applied to the substrate.

12. A method according to any one of Claims 9 to 11, wherein a further component, particulate stone, is intimately mixed with said particulate carbonaceous material, particulate cementitious material and said bitumen S: emulsion in said mixing step.

13. A method according to any one of Claims 9 to 12, wherein said bitumen emulsion is anionic bitumen emulsion.

14. A material for laying a traffic bearing course substantially as herein described with respect any one of the Examples. 1h a s d

15. A method substantially as herein described. 9 a: patent (ss floppy).