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
  • E01C7/00—Coherent pavings made in situ
  • E01C7/08—Coherent pavings made in situ made of road-metal and binders
• • 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
  • E01C7/08—Coherent pavings made in situ made of road-metal and binders
  • E01C7/18—Coherent pavings made in situ made of road-metal and binders of road-metal and bituminous binders
• • 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
  • E01C7/08—Coherent pavings made in situ made of road-metal and binders
  • E01C7/35—Toppings or surface dressings; Methods of mixing, impregnating, or spreading them
  • E01C7/351—Toppings or surface dressings; Methods of mixing, impregnating, or spreading them with exclusively hydraulical binders; Aggregate, fillers or other additives for application on or in the surface of toppings with exclusively hydraulic binders

Definitions

• the present invention relates to a method of providing a road surface with an overlay, normally for general road maintenance and restoration of good antiskid properties.
• the discussed cold methods can be modified so as to be much better applicable even for the said more critical works.
• a basic idea is that the finer stone fraction is applied not as an individual full layer of stones on the top of the lower, coarser stone fraction, but only to the extent of filling out the upper voids of the lower layer of coarse stones, in association with another basic idea of applying the required binder to the finer stone fraction not as a bed underneath this fraction, but rather by a spraying of a low viscosity binder against the top side of this fraction, such that the binder, seeking rapidly downwardly, will very soon effect an initial binding of the finer stone fraction, which will also be mechanically stabilized in the upper voids between the underlying coarse stones.
• the downwardly penetrating low-viscid binder which, however, may be an emulsion of a high viscid bitumen material, which may be adapted to 'break' relatively soon so as to cause an effective binding both of the lower coarse stone fraction to the former road surface and of the upper finer stone fraction to orin the upper voids of the lower, coarse stone fraction, without the finer stones being present above the top side of the coarse stone layer.
• the finer stone will not behave as loose stones, and the binder will soon sink down from the surface, whereby the traffic on the road can soon be resumed.
• the major part of the surface area will be constituted by the smaller stones, which will provide a texture in favour of good skid resistance and low noise generation.
• the bituminous binder will effectively fill out the voids between the stones at least in the lower half of the overlay, thus providing for improved stress releiving and waterproofing.
• bituminous binder preferably a polymer modified bituminous emulsion to ensure waterproofing and perfect bonding to the old surface as well as for temporarily securing the first chipping layer in place.
• the first chipping layer of relatively coarse stones e.g. 12-14 mm
• the first chipping layer of relatively coarse stones is laid out in a single layer, preferably not fully compact, so as to cover some 95% of the surface area.
• a second layer of smaller nominally single sized chippings e.g. 6-7 mm is then applied, taking care not to disturb greatly the first layer, the dosage being controlled to the effect that the second layer fills up the voids between the coarse stones without any substantial overheight therein.
• the combined layers are compacted to interlock the second layer with the first layer and make the top sides of the two layers flush with each other.
• a low viscosity bituminous binder preferably a polymer modified bituminous emulsion with good adhesion and breaking characteristics, is evenly applied to the surface such that the remaining voids in the first layer are filled and a surface texture is clearly visible.
• the binder will flow down in contact with all the stones, thus producing an effective bonding of and in the combined layer.
• the treatment is finished by applying a thin top layer of still smaller chippings, e.g. sand, in order to prevent contact of the binder with the traffic tyres in the initial stages and to aid the quick build up of skid resistance.
• chippings e.g. sand
• the actual quantities of chippings, their grading and size, can be used to calculate the voids in the layers and to dictate the binder addition to achieve the desired texture, given the traffic weight and speed, the degree of site difficulty and the characteristics of the existing road surface.
• the chippings in the second layer are preferably pre-coated with bituminous binder or chemically coated in order to ensure that the applied bituminous binder or binder emulsion will penetrate the underlying layer and not break so quickly as to form a thick coating on the surface aggregate. Also, the overlay will then be better stabilized should water be present, particularly when freeze-thaw cycles occur.
• hot binders such as cutback bitumen would not allow for satisfactory grouting or penetration of the binder into the voids, unless the viscosity is undesirably low, and would not, therefore, provide the same durability as when using emulsion binders, which may be of low viscosity, but nevertheless be based on high viscosity bitumen.
• the invention will comprise also the use of hot binders, which may present advantages in terms of costs on lightly trafficked roads.
• the stones in the first layer should not be coarser than 20-24 mm and not finer than some 8 mm.
• the secondary stones should preferably be only one fraction smaller, e.g. 8-10 mm, so that these stones will still be 'relatively large' and not liable to be deposited on top of each other.
• the invention is not limited to the use of any special aggregate or binder qualities, so the method may be widely varied in this respect, as long as satisfying results are obtained, subject to different requirements.
• both of the chipping layers may be pre-coated.
• other materials e.g. recycled asphalt, graded into the respective fractions.
• a certain content of fine fractions may be tolerable in both chippings, and in connection with graded aggregates the fine fraction may be used in the final top layer, when used.
• the first layer may be a low cost aggregate such as gravel stones with low skid resistance properties, followed in the second layer by a higher skid resistant chipping, thus maximizing the resources of higher cost quality aggregate.
• various artificial aggregates may be used, e.g. slag or calcined bauxite, cementious mortar or cement concrete, formed or crushed, or any suitable waste product, with or without pre-coating.
• geotextiles or other fibre reinforcement between the layers, including grids prepared from metal or polymer compounds, especially between the existing road surface and the first layer.
• the binder may be selected from many usable substances such as cutback bitumen, foamed bitumen and modified versions of these with additives or polymers or fibres or filler, added to the binder or during construction, and all emulsion variants thereof.
• any suitable breaking control system may be used.
• Further binder examples will be thermo-setting binders and other resin binders including polyurethane, acrylic, polysulphide, expoxide, and all two component binder systems.
• Different binders may be selected for the respective grouting application and bond coating, where the latter is used.
• a cost saving may be obtained by using unmodified bituminous binder in one or more applications.
• a slurry surfacing as a final wearing surface or a fine slurry seal, possibly applied as a spray.
• a suitable slurry will be a stone fraction of 0.2-0.3 mm in a fast breaking bituminous emulsion.
• the invention will be applicable also in connection with the construction of new roads and on cement concrete, on airfields, car-park decks etc., and even for providing waterproof layers in buildings. Aggregates may be coloured, if desired.

Landscapes

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

Applications Claiming Priority (4)

Publications (2)

Family

ID=8103958

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (1)

Family Cites Families (4)

• 1994
  • 1994-11-28 DK DK135694A patent/DK135694A/da unknown
• 1995
  • 1995-11-28 DE DE69523332T patent/DE69523332T2/de not_active Expired - Fee Related
  • 1995-11-28 EP EP95937001A patent/EP0795059B1/en not_active Expired - Lifetime
  • 1995-11-28 AU AU39245/95A patent/AU3924595A/en not_active Abandoned
  • 1995-11-28 WO PCT/DK1995/000478 patent/WO1996017130A1/en not_active Ceased

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