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WO2015048838A1 - Mélange pour construction de routes et ses procédés de mélange et de compactage - Google Patents

Mélange pour construction de routes et ses procédés de mélange et de compactage Download PDF

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Publication number
WO2015048838A1
WO2015048838A1 PCT/AU2013/001127 AU2013001127W WO2015048838A1 WO 2015048838 A1 WO2015048838 A1 WO 2015048838A1 AU 2013001127 W AU2013001127 W AU 2013001127W WO 2015048838 A1 WO2015048838 A1 WO 2015048838A1
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WO
WIPO (PCT)
Prior art keywords
mixture
fines
aggregates
moisture content
road
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
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PCT/AU2013/001127
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English (en)
Inventor
Simon BRUCE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STABILCO INTELLECTUAL PROPERTY Ltd
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STABILCO INTELLECTUAL PROPERTY Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by STABILCO INTELLECTUAL PROPERTY Ltd filed Critical STABILCO INTELLECTUAL PROPERTY Ltd
Priority to EP13894954.0A priority Critical patent/EP3071753A4/fr
Priority to PCT/AU2013/001127 priority patent/WO2015048838A1/fr
Publication of WO2015048838A1 publication Critical patent/WO2015048838A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C3/00—Foundations for pavings
    • E01C3/06—Methods or arrangements for protecting foundations from destructive influences of moisture, frost or vibration
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C21/00—Apparatus or processes for surface soil stabilisation for road building or like purposes, e.g. mixing local aggregate with binder
    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C7/00—Coherent pavings made in situ
    • E01C7/02—Coherent pavings made in situ made of road-metal without binders
    • E01C7/04—Coherent pavings made in situ made of road-metal without binders of broken stones, gravel, or like materials

Definitions

  • the present invention relates to construction base material and in particular to a mixture for a road formation and methods for blending and compaction thereof.
  • the invention has been developed primarily for use in road bases and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use, and may be equally be applicable to other applications also including open-cut mine roads, underground mine roads, railway formations, airport pavements, reservoir linings, dams and the like.
  • drainage away from the road base is often imperfect including at least on account of inferior drainage layers, buildup of fines material, blockage or drains, and the like.
  • existing granular interlock structures are often damaged by a buildup of water in the road base which weakens the shear strength of the road base.
  • the present invention seeks to provide to a mixture for a road formation and methods for blending and compaction thereof, which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative.
  • a mixture for a road formation comprising fines and aggregates, wherein the ratio of the fines to the aggregates is selected in accordance with a desired permeability.
  • the ratio of fines to aggregate is selected in to reduce the permeability.
  • the ratio fines is sufficient to as to substantially fill the aggregate interstices.
  • At least the filling of the aggregate interstices effects the desired permeability.
  • the desired permeability is less than 5 x 10 ⁇ 8 ms "1 .
  • the desired permeability is less than 4 x 10 "8 ms "1 .
  • the desired permeability is less than 3 x 10 "8 ms "1 .
  • the desired permeability is less than 2 x 10 "8 ms "1 .
  • the desired permeability is less than 1 x 10 "8 ms "1 .
  • the mixture comprises greater than 7% minus 75 ⁇ fines.
  • the mixture comprises greater than 10% minus 75 ⁇ fines.
  • the mixture comprises greater than 12% minus 75 ⁇ fines.
  • the mixture comprises greater than 20% minus 75 ⁇ fines.
  • the aggregates type is selected in accordance with strength.
  • the strength of the aggregates type selected has a strength beneath a threshold.
  • the strength is a wet 10% fines value of less than 95kN.
  • the strength is a wet 10% fines value of less than 70kN.
  • the strength is a wet 10% fines value of less than 50kN.
  • the strength has a wet/dry variation of less than 35%.
  • the strength has a wet/dry variation of less than 45%.
  • the strength has a Los Angeles Test value of less than 50%.
  • the strength has a Los Angeles Test value of less than 40%.
  • a plastic index of at least one of the fines and the aggregates type is selected in accordance with a plastic index threshold.
  • the plastic index is beneath the plastic index threshold.
  • the plastic index threshold is 6.
  • the plastic index threshold is 12.
  • the plastic index threshold is 20.
  • the aggregates type is selected in accordance with a shape characteristic.
  • the shape characteristic is a sphericity.
  • the aggregates type is selected for asymmetry.
  • the sphericity is greater than 35% by proportional calliper.
  • the sphericity is greater than 35% by flakiness index.
  • t e ratio of the fines to the aggregates is selected further in accordance with a post-compaction aggregate compression state.
  • the compression state is a tri-axial compression state.
  • the ratio of fines to aggregates is selected to increase the tri-axial compression of the aggregate by the fines.
  • the ratio of fines to aggregates is selected to decrease aggregate particle contact.
  • the ratio of fines to aggregates is selected to decrease aggregate granular interlock.
  • either the fines or aggregates contain a desired pH.
  • the desired pH of either the fines or aggregates is greater than 8.
  • the desired pH of either the fines or aggregates is greater than 9.
  • the desired pH of either the fines or aggregates is greater than 10.
  • At least one of the fines and aggregates selected in accordance with a desired moisture content.
  • the desired moisture content is a maximum moisture content
  • the maximum moisture content is adapted to maximise shear strength and substantially reduce hydraulic pore pressure during compaction
  • the maximum moisture content is greater than 2% below optimum moisture content as determined by Proctor method.
  • the maximum moisture content is greater than 3% below optimum moisture content as determined by Proctor method.
  • the aggregates comprise at least one of coal washery rejects; quarried natural rock; quarry scalps; recycled brick and tile, crushed concrete, rock; sandstones; weak sandstones; shales, mine gangue and industrial aggregate waste.
  • the fines comprise at least one of low grade material; waste material; recycled material and non-virgin excavated rock.
  • the fines comprise at least one of fly ash; red mud; lime slurry; industrial slurry; bag house dust; mine tailings and incinerator dust.
  • a road base comprising the mixture as described herein.
  • a method of blending a mixture for a road base comprising blending material so as to provide a mixture described herein.
  • a method of milling a mixture for a road base comprising milling road base material in accordance with a desired moisture content.
  • the mixture comprises fines and aggregates and wherein at least one of the type of fines and aggregates is selected in accordance with the desired moisture content.
  • a method of compacting a road base comprising compacting a mixture as described herein.
  • a method of compacting a road base comprising compacting a mixture having a moisture content of greater than 2% below optimum moisture content as determined by Proctor method.
  • a method of compacting a road base comprising compacting a mixture having a moisture content of greater than 3% below optimum moisture content as determined by Proctor method.
  • a method of compacting a road base comprising a compaction stage comprising less than 5 compaction passes and usage stage comprising vehicular traffic usage.
  • a method of compacting a road base comprising a compaction stage comprising less than 2 compaction passes and usage stage comprising allowing vehicular traffic usage.
  • a mixture for a road base when placed in a 150mm thick layer wherein the mixture comprises a ratio of fines to aggregates and moisture adapted to achieve a density of greater than 98% standard compaction (Proctor) after the second compaction pass using a road roller of less than 20 tonnes in weight, but greater than 12 tonne in weight.
  • a mixture for a road base wherein the mixture comprises a ratio of fines to aggregates adapted to achieve a density of greater than 2.2 t/m3 after a first compaction pass using a road roller of less than 20 tonnes in weight.
  • Fig. 1 shows a road formation in accordance with the prior art
  • Fig. 2 shows a comparison of prior art road formation materials and the mixture as per the embodiments of the present invention
  • Fig. 3 shows a comparison of the resultant density of the compaction process and comparing prior art road formation materials and the mixture as per the embodiments of the present invention.
  • the mixture will be described herein with reference primarily for use as road base construction but that the mixture should not be construed as being limited to this application. Specifically, the mixture may be equally suited for other construction application also including for the use in airport runways and pavements, mine haul roads and underground roads; layers beneath railway ballast and, at least on account of the low permeability of the mixture as will be described in further detail below, for reservoir construction waste repositories, landfall liners and capping, dam construction and the like.
  • matrix mixture the mixture according to the embodiments described herein will be referred to for convenience purposes as the "matrix mixture” so as to distinguish the matrix mixture from existing road base material wherein, as will be appreciated from the below description, the term matrix refers to one of the characteristics of the matrix mixture being the supportive and cushioning tri-axial compression of aggregates by fines providing the advantages, efficiencies, benefits and the like as described herein, such as reduced permeability.
  • the granular road base material beneath the wearing surface on sealed roads and at the surface for unsealed roads contains road base which can become water affected during in pavement life.
  • the passage of vehicle wheels over a granular road base imparts the load through the roadbase to the layers below. If the roadbase becomes moisture affected, this load is transmitted to the moisture affected road base which has lower shear strength and pavement failure can occur through rutting and shoving.. If moisture content continues to increase high pore pressures can develop within the road base. High pore pressures and restricted drainage creates an upward pressure towards the surface and blowouts and potholes form at the surface.. The edges of the pothole can be further eroded as granular road base disappears from the crater. There are two failure mechanisms working here: 1 ) initial instability and increased deformation by shear as moisture increases; and 2) pothole blowouts as moisture increases further and excessive pore pressures develop.
  • the road formation beneath the road surface, the road formation comprises a series of layers wherein the layers are intended possess increasing permeability downwards to be permeable such that any water entering the structure from the top is dispersed downwards away from the road base towards a bottom drainage layer from whence the water can be drained away so as to prevent the adverse effects of moisture and pore pressure on the sheer strength of the road base.
  • conventional road bases comprise discrete particles of proportionally sized aggregates that are compacted such that the each aggregate particle interlocks with and bears against adjacent aggregate particles (granular interlock) so as to form a strong, relatively stiff, coherent layer that retains some permeability.
  • the drainage layer of the road formation comprise aggregates and is designed to facilitate drainage of water down and away from the upper, higher stress layers of the road formation.
  • FIG. 1 there is shown a prior art road formation 100 comprising a base 105 adapted to allow the permeation of water therethrough to a drainage layer 1 10. Also shown is the desired path 1 15 of such water drainage wherein ideally the water drains from the base 105 through to the lower drainage layer 1 10 and away from the road formation 100.
  • a road base comprising the matrix mixture such that, as opposed to being designed to allow the permeation of water therethrough, the road base comprising the matrix mixture is adapted to reduce permeability so as to prevent the ingress of water within the road formation the first place. In this manner, the water is dispersed laterally from the road surface as opposed to permeating therethrough.
  • the matrix mixture advantageously substantially ameliorates ingress or eliminates water variation and increase or saturation within the road base so as to maintain the sheer strength of the road base and prevent the development of high pore pressures.
  • the matrix mixture exhibits superior long term shear strength and low permeability by comprising a mixture of aggregates and fines wherein the fines are adapted to substantially fill the interstices between the aggregate material so as to prevent the permeability of water through the interstices of the aggregate material.
  • fines fines
  • microfines fines
  • the terms as used herein may infer particles sizes of less than 75 ⁇ . (75 micro or 75 ⁇ or 75 x 10 "6 m)
  • Such a matrix mixture further enhances the compaction process allowing greater compaction than when compare to existing road base material.
  • the fines of the matrix mixture is provided in sufficient quantities so as to reduce aggregate-aggregate granular interlock of the aggregate material.
  • Such granular interlock provides the stiffness and strength of existing road bases.
  • the matrix mixture further advantageously provides a cohesive road base which is resilience to shear and the like at least on account of heavy traffic, ground subsidence and the like.
  • Conventional aggregate-aggregate interlock roadbase requires high strength/durability materials to prevent their breakdown over time, with the repeated traffic loading. The load is transmitted downwards from aggregate to aggregate, by the friction at the aggregate-aggregate boundaries, via pathways through the granular material.
  • the aggregates are compacted such that the strength of the layer is directly related to the strength, durability and soundness of the aggregates (determined by various test methods specified by road authorities) so as to provide the underlying strength of the road base for the life of the road.
  • the drainage layer of existing road bases comprises a mixture of fines and coarse aggregates which eventually becomes impermeable as additional fines collect in the interstices so as to block the interstices between the coarse aggregate material so as to hinder permeability.
  • the matrix mixture for use in road bases comprises a mixture of fines and aggregates wherein the fines is of sufficient quantity such that aggregate on aggregate contact is reduced.
  • the strength of the road base is now rather directly related to the tri-axial compressive strength producing a road base having comparable strength to the above-mentioned existing road base while having the advantage of allowing for the use of aggregate material having lower strength properties when compared to existing aggregate material.
  • the matrix mixture providing an impermeable mixture there is advantageously provided the reduction of moisture variations in the material which result in improved shear strength, and reduction or elimination of hydrostatic pore pressure build up within the matrix mixture and furthermore, on account of the coarse aggregate material being cushioned by the fines, there is no aggregate-aggregate contact wear, crushing, abrasion and the like of the aggregate material reducing the above-mentioned failures of existing road surfaces on account of reduced shear strength and/or high pore pressure and coarse material crushing and abrasion.
  • the matrix mixture provides a road base that is cohesive such that cracking is reduced or eliminated on account of the above-mentioned traffic or subsurface destabilisation effects which adversely affect existing road bases.
  • the road base comprising the matrix mixture is able to "self heal” so as to maintain the integrity of the road base.
  • the matrix mixture road base does not suffer from the disadvantage of existing road bases with respect to the leeching of pollutants, chemicals and the like. Furthermore, given that there is substantially no chemical leeching, there may be even incorporated known pollutants, toxic chemicals and the like to provide advantages not only in waste disposal but also alternatively or additionally in the enhancing the physical and chemical characteristics of the matrix mixture.
  • the shape of the material plays an important factor in compaction, density and permeability. Specifically, as alluded to above where existing road bases derive their strength from the interlock of adjacent aggregate material, such aggregate material is therefore specified in accordance with particle size, shape, strength and other physical parameters so as to enhance the granular interlock. Specifically, the more cubic the aggregate material with prescribed particle size distribution, the greater the strength of the interlock.
  • an important characteristic of existing road bases is the strength characteristics and in this regard, coarse aggregates are sourced predominantly from virgin excavated materials such as materials excavated from quarries which material is subsequently crushed, screened and sized to ensure that only aggregates with specific strength, shape and size, and particle size distribution characteristics are employed for the purposes of forming existing road bases.
  • waste materials from previously used products or processes are rarely suited for acceptance in accordance with the criteria set for the coarse aggregate layer predominantly because of quality control (consistency of characteristics) with regards to the strength, size, shape and particle size distribution.
  • the material employed for the matrix mixture need not meet such stringent requirements.
  • the aggregate material is supported by the fines material in tri-axial compression so as to advantageously allow for the use of aggregate material comprising lower or substandard strength, shape size and particle size distribution characteristics.
  • waste aggregate material, and even fines material may be employed for the purposes of road bases dramatically reducing the cost of such road bases.
  • Plastic fines are explicitly excluded from the use in existing road base materials by the specifications of the road authorities because plastic fines material properties, and particularly shear strength is adversely affected by moisture in conventionalroad bases.
  • the Plastic Index of materials is defined by the Liquid Limit and Plastic Limit under the Atterberg Test and road authorities typically place limits on the Plastic Index, and sometimes the Liquid Limit.
  • the limits, according to existing arrangement, for the Plastic Index of between 0 and 6 for road base materials is almost universally adopted by road authorities.
  • Some road authorities specify a liquid Limit of between 20 and 30 for existing road base materials and an upper limit of 20 for the Plastic Limit.
  • the low permeability of matrix mixture permits the use of plastic fines provided that the fines are placed and compacted at substantially the correct moisture content during construction.
  • matrix mixture comprise low permeable materials that substantially prevent the ingress of moisture and maintain low moisture content within the body of the material during the pavement life, any plastic material used for the matrix mixture is not substantially affected by moisture and can therefore be used as a material for the matrix mixture.
  • the inclusion of clays or plastic material further reduces the permeability of the matrix mixture.
  • Plastic Limit limits for matrix mixture are substantially 0 to 12 or even 0 to 20 or more depending on the nature of the clay materials.
  • the limits for Liquid and plastic limit may vary depending on the application.
  • material types generally excluded for use in road base construction and the like on account of inferior linear shrinkage properties may now be used such as sandstones, shales, baghouse dusts and industrial wastes including gypsum and lime.
  • Matrix mixture can therefore contain waste and toxic aggregates or fines (subject to environmental approval of authorities).
  • Materials with pH from 0 to 14 can be accommodated, either in part, or in total in the matrix mix and the matrix mixture can have a pH between 0 and 14, which control is determined by environmental authorities.
  • conventional roadbases made from virgin natural quarried materials typically have a pH between 6 and 8 on account of the inherent properties of the source rock.
  • pozzolanic fines in the matrix material which possesses a pH >12.4 will generate a pozzolanic reaction and the material will develop increased shear strength and tensile strength.
  • This pozzolanic reaction can be controlled, and therefore the strength gain can be controlled, by either controlling the quantity of pozzolan available for the reaction or the availability of cations supplied through either the binder or the inherent pH of the aggregate and/or the fines .
  • the bound matrix with increased strength and low permeability becomes an improved medium in which to lock in wastes and toxic materials.
  • the construction of roads with matrix mixture containing pozzolanic materials permits the rehabilitation and treatment of the unbound structure at the end of its service life by either tyning and shaping at low moisture; and/or the addition of fines and/or aggregate for the reconstruction of an unbound granular pavement (mechanical stabilisation); and/or the addition of foamed bitumen (bitumen stabilisation); and/or by addition of a binder or cement to produce a bound pavement (chemical stabilisation).
  • mechanical stabilisation mechanical stabilisation
  • bitumen stabilisation foamed bitumen
  • bitumen stabilisation foamed bitumen stabilisation
  • a binder or cement to produce a bound pavement
  • the advantages of a bound pavement with pozzolanic fines is the pozzolanic reaction which progresses slowly by comparison with the cementicious reaction.
  • the particular advantages in road construction include 1 ) a slow reaction rate which permits extended time for construction and reworking, 2) the matrix mixture can be trafficked before strength gain is achieved (no curing time as would be the case for cement and concrete), 3) more time for high compaction under traffic before strength gain, 4) pozzolanic reaction is a low heat reaction so reduced thermal shrinkage occurs as compared to cement and concrete, 5) the material can be stockpiled for a few days before use and 6) autogenous healing of pozzolanic materials if cracks develop in the bound structure.
  • pozzolanic fines increases the range of options available in pavement design, construction, reduced maintenance and rehabilitation at the end of the service life of the original pavement.
  • FIG. 2 there is shown a visual comparison between existing road base material 205 and the matrix mixture 210.
  • the existing road base material 205 comprises aggregate material 210 compacted such that the aggregate particles abut against adjacent aggregate particles.
  • the interstices between the aggregate particles 210 is open so as to allow the permeation of water therethrough.
  • the permeation of water through the upper layers of the road surface is a desired effect so as to attempt to achieve the drainage of the water away from the road base to the drainage layers of the road base.
  • each aggregate piece abuts against the adjacent aggregate particles resulting in aggregate on aggregate/point-point contact.
  • the road base material 205 is given in figure 2 generally shows adjacent aggregate particles 210 having been compacted as far as is possible.
  • such compaction provides the strength characteristics of the road base which is a desired outcome for conventional arrangements.
  • inefficiencies in the lower drainage layers may result in moisture increase within the interstices of the aggregate particles 210, reducing shear strength and creating hydraulic pressures or "pumping" which disengages the granular interlock of the aggregate particles 210 resulting in failure.
  • the matrix mixture 210 comprising a mixture of aggregates 210 and fines 215.
  • the fines 215 are provided in sufficient quantity so as to reduce granular interlock between the aggregate particles 210 such that the aggregate particles are cushioned or suspended by the fines "matrix".
  • the ratio of the fines 215 to the aggregates 210 is selected in accordance with a desired workability and permeability, and in particular to increase compaction and reduce the permeability of the matrix mixture 210.
  • the fines 215 substantially fill the interstices between the aggregate particles 210 such that water cannot permeate between the aggregate particles 210, advantageously providing the water permeability characteristics and the resultant advantages as discussed above.
  • road bases with fines content below 7% which is typical of hard rock quarried material, has permeability greater than 5 x 10 "5 ms 1 .
  • the water permeability characteristics exhibited by the matrix mixture depends on the road authority requirements but generally offers a maximum permeability of less than 1 x 10 "8 ms "1 .
  • Particle Size distribution of the matrix material as compared to existing arrangements
  • Conventional road base materials are designed on particle size distribution to achieve maximum or tightest packing.
  • Road authorities particle size distribution specification requirements are set based on the Fuller and Thompson equation below. This is not the basis for matrix mixture.
  • the matrix mixture relies on particle surface area for mix design. In this the design is similar to asphalt concrete mix designs in which voids are important.
  • Matrix mixture improved workability (reduced energy to achieve compaction) and increased density result in reduced permeability. This is a holistic approach which accounts for all the particle surface properties such as shape, dimension, angularity, surface roughness, texture and asperities.
  • Particle size distribution or size grading is the principle means by which road authorities try control materials and optimise the particle size distribution to achieve or maximise packing during compaction - to increase density of the road base. Almost without exception every road authority places limits on the particle size distribution.
  • n coefficient, generally accepted between 0.5 and 0.35 and most often at 0.45.
  • the matrix mixture is able to comprise a higher percentage of fines in the -75 ⁇ size fraction than as permitted by the relevant authorities for road base aggregate mixtures.
  • exemplary maximum fines content is permitted by relevant road authorities is presented in the following table: Jurisdiction % Minus 75 micron Road Authority Specification allowed
  • fines In most countries fines is capped at 10% maximum passing 75 ⁇ . Conversely, in the matrix mixture, the fine particles fill interstices to reduce permeability by surrounding the aggregate particles such that when compacted, the aggregate particles are placed in tri-axial compression. This "cushion of fines” protects the aggregate particles from “aggregate-on-aggregate” forces, prevents intersticial dilatancy which results in shear caused by the rotation and disengagement of aggregate particles, and improves the durability of the matrix mixture through low permeability.
  • the matrix mixture will comprise fines particle with a percentage of -75 ⁇ fines substantially greater than those shown above, such as those comprising greater than 10%, 12%, 14% and even 16% fines by mass. Aggregate strength, soundness and durability of the matrix mixture as compared to existing arrangements
  • the cushioning effect of the fines allows for aggregates of inferior strength (that is uncompressed strength) yet while providing for the matrix material exhibiting strength characteristics (compressed strength) on par with existing arrangements yet while not suffering from the disadvantages of existing arrangements including those relating to permeability.
  • the allowance for use of weaker aggregate material advantageously allows for the use of waste material and the like which would otherwise be ineligible for use in road base construction.
  • material properties can be measured in differing manners also including particle size distribution, Atterberg limits (plasticity - clay contents), California Bearing Ratio CBR, aggregate particle strength durability and soundness, shape and proportion.
  • material/aggregate strength, durability and soundness can be measured by several different methods: 10% Fines Value; Wet/Dry Strength Varitaion, Los Angeles Abrasion test, Aggregate Crushing Value; Ultrasonic velocity etc. and each road authority often has unique variations of these test methods to test aggregate particle strength.
  • the fines filling the interstices between the aggregate particles support the aggregate particles so as to spread forces acting on each aggregate particle as opposed to conventional aggregate particle granular interlock which experiences point forces.
  • aggregate particles of lower strength may be employed as compared to those mandated by existing specification.
  • the shape of the aggregate particles as compare to existing arrangements. Specifically, as will be described in further detail now, the shape of the aggregate particles when used in the matrix mixture may have a greater asymmetry as compare to the specification for aggregate particles for existing road base.
  • the fines of the matrix mixture adequately fill the interstices between the aggregate particles of the matrix mixture so as to accommodate asymmetric aggregate particles.
  • symmetric aggregate particles are desirous so as to allow for a rigid and effective aggregate particle granular interlock.
  • the moisture content of the matrix mixture upon application is generally far less than the moisture content of existing road base materials upon application.
  • the road base material is wet to approaching the optimum moisture content so as to provide lubrication (reduce friction and shear strength) and assist in the compaction process.
  • the wetting of the existing road base material enhances the slippage of the aggregate particles so as to enhance the compaction of the resultant aggregate particle granular interlock.
  • the existing arrangements requiring the wetting of the road base material application comprises disadvantages not only on the effect of increased moisture on the strength of materials below the road base, but also the wastage of water, and also in the time period mandated for the drying of the road base prior to the allowance of traffic thereupon.
  • the matrix mixture it is desirous to have a low moisture content. It is the fines that provide the lubrication required for compaction. Specifically, a low moisture content reduces reactionary hydraulic pore pressures which would otherwise impeded the compaction process. Furthermore, the fines content increases the workability of the matrix material. Furthermore, the low moisture content of the matrix mixture allows the resulting road base comprising the matrix mixture to be ready for traffic sooner than compared to existing road bases which require a drying period. For example, for conventional road base mixtures, a dry back to either 70% of optimum moisture content or 70% of saturation is required which may take up to 2 weeks of dry weather to obtain.
  • the optimum moisture content is the water content at which a specified compaction force can compact a mass to its maximum dry unit weight determined by the Proctor test. As such, as is evident from the above specifications, there is a tight threshold about the optimum moisture content.
  • the threshold about the maximum moisture content can be greater than 2% such as up to 5% below optimum moisture content as determined by Proctor test. That is, if the optimum moisture content measured by the Proctor test is 9%, then the matrix mix moisture content can be 7% to 4% by mass.
  • the moisture is regulated and controlled.
  • aggregate material is usually sourced from virgin natural rock excavation, followed by crushing, screening, blending, sorting and the like.
  • the matrix mixture makes allowance for inferior materials including in terms of strength, shape and particle size distribution and therefore advantageously allows for the usage of waste materials and the like.
  • the aggregate may be sourced from various sources including coal washery rejects, quarry scalps, recycled brick, concrete or natural rock including weathered and sedimentary rock, weak sandstones, shales and mine gangue, industrial aggregate wastes, recycled glass, power station ash, steel slags.
  • the fines materials for the matrix mixture may be sourced from various sources including fly ash, red mud, lime and industrial slurries, bag house dust, mine tailings and incinerator dust, recycled glass.
  • intensive compaction energy is employed to increase the aggregate on aggregate granular interlock so as to provide the permeable and rigidity of the road base.
  • compaction passes may be employed.
  • a maximum of two passes with a vibratory roller followed by two passes with a static roller is employed whereafter traffic may be allowed onto the road. This is compare to existing compaction processes where up to 20 passes or more may be required to achieve the desired aggregate on aggregate granular interlock.
  • Road authorities generally control layer thickness when road base is spread and compacted.
  • the thickness of each layer is controlled and limited (in the case of most Australian road authorities to 150mm) to ensure that the passage of the compaction roller achieves the required compaction density at the bottom of the layer.
  • the matrix mixture possess superior workability so as to aid in compaction to the required density in layers of 250mm or more. This efficiency in time, energy and effort translates to significant cost savings.
  • vehicular traffic further enhances the compaction process, and as such, it is often times desirable to introduce traffic as soon as possible.
  • FIG. 3 there is shown a graph 300 comparing the resultant density as a result of compaction of the matrix mixture material and conventional road base material.
  • the graph 300 shows the resultant density of the matrix mixture 305 when compared to the resultant density of conventional road base material 310.
  • the matrix mixture material attains a greater density sooner and with less energy than conventional road base material.
  • the road base comprising the matrix mixture attains a density which would require between five or six compaction passes for conventional road base material. It therefore requires less time to compact.
  • the aggregates and fines will be blended in proportion according to the mix design and with the addition of sufficient water , typically within pug mills to produce a consistent quality product with the desired material properties.
  • the water content of the matrix mixture is controlled. Specifically, as alluded to above, the water content of the matrix mixture is controlled so as to attain moisture below optimum moisture content as determined by Proctor test.
  • conventional materials require moisture within 2% of Optimum moisture content to achieve compaction. At this high moisture, conventional materials must be allowed time (2 to 4 days) to dry back, release the pore water pressures developed during compaction, and develop shear strength. Trafficked immediately these materials typically develop ruts in the wheel paths, shove at the edge of wheel paths and develop potholes.
  • the matrix mixture can be placed and compacted at moistures below 2% of Optimum moisture content. At low moisture high pore pressure does not develop during compaction. As a result the matrix mixture possess adequate shear strength at the time of placement to enable traffic immediately after placement. Furthermore, once compacted, but still unsealed, the matrix mixture is much less likely to be deformed under traffic in wet weather because the matrix mixture possess low permeability.
  • An effective manner at in which to control the moisture content of the resultant matrix mixture is in the selection of materials, and specifically in the selection of the fines materials.
  • fly ash has a particular dryness and may be utilised in the blending process to reduce the moisture content of the resultant matrix mixture.
  • a mixture of different types of fines materials may be employed also depending on the application.
  • Such a blending process is distinct from existing blending processors wherein during the blending processes of existing arrangements, it is rather the resultant strength of the mixture which is important in which case the drying back of the material is important to achieve shear strength, or various additives such as binders, cements and geopolymers and the like are added to enhance the resultant strength characteristics of the final mixture.
  • the aggregates, fines and water constituents need to be mixed proportionally to produce a consistent quality blended product.
  • the ingredient materials are variable, both in their particle size distribution and moisture content, such that proportioning and moisture must be controlled during production to ensure.

Landscapes

  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Road Paving Structures (AREA)

Abstract

Cette invention concerne un mélange pour construction de routes telles que des routes d'exploitation minière à ciel ouvert, des galeries d'exploitation minière souterraine, des voies ferrées, des revêtements aéroportuaires, des revêtements de réservoirs, des barrages et similaires. Ledit mélange comprend un rapport des fractions fines (215) aux granulats (210) tel qu'il présente des propriétés comprenant une perméabilité réduite, une tolérance des matières inférieures, un taux d'humidité réduit et similaires. L'invention concerne en outre un procédé de mélange et de compactage dudit mélange.
PCT/AU2013/001127 2013-10-02 2013-10-02 Mélange pour construction de routes et ses procédés de mélange et de compactage Ceased WO2015048838A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP13894954.0A EP3071753A4 (fr) 2013-10-02 2013-10-02 Mélange pour construction de routes et ses procédés de mélange et de compactage
PCT/AU2013/001127 WO2015048838A1 (fr) 2013-10-02 2013-10-02 Mélange pour construction de routes et ses procédés de mélange et de compactage

Applications Claiming Priority (1)

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PCT/AU2013/001127 WO2015048838A1 (fr) 2013-10-02 2013-10-02 Mélange pour construction de routes et ses procédés de mélange et de compactage

Publications (1)

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WO2015048838A1 true WO2015048838A1 (fr) 2015-04-09

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EP (1) EP3071753A4 (fr)
WO (1) WO2015048838A1 (fr)

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CN113445381A (zh) * 2021-07-09 2021-09-28 包头市公路工程股份有限公司 一种水泥石膏复合稳定钢渣基层施工工法
CN115262307A (zh) * 2022-05-19 2022-11-01 山东高速基础设施建设有限公司 一种赤泥基轻质路基施工方法
CN117418422A (zh) * 2023-12-19 2024-01-19 中交建筑集团东南建设有限公司 一种砂土混合翻拌的再生路基填筑施工工艺

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CN112853841A (zh) * 2021-01-14 2021-05-28 籍晓宝 一种高速路公路路基及其施工方法

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109281235A (zh) * 2018-11-29 2019-01-29 西南交通大学 一种火山熔渣铁路路基及其修筑方法
CN113445381A (zh) * 2021-07-09 2021-09-28 包头市公路工程股份有限公司 一种水泥石膏复合稳定钢渣基层施工工法
CN115262307A (zh) * 2022-05-19 2022-11-01 山东高速基础设施建设有限公司 一种赤泥基轻质路基施工方法
CN117418422A (zh) * 2023-12-19 2024-01-19 中交建筑集团东南建设有限公司 一种砂土混合翻拌的再生路基填筑施工工艺
CN117418422B (zh) * 2023-12-19 2024-03-08 中交建筑集团东南建设有限公司 一种砂土混合翻拌的再生路基填筑施工工艺

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Publication number Publication date
EP3071753A1 (fr) 2016-09-28
EP3071753A4 (fr) 2018-01-10

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