INVENTION CONCERNING PRODUCTION OF ASPHALTMIX

Abstract: The invention consists of a mixing process for the production of asphalt mixes, that include at least aggregate divided in coarse-and a fine fraction, bituminous liquid and filler that replace the miximg process based on forced mixing, through spreading the bituminous liquid, filler and fine fraction over the surface of the flowing coarse fraction, in the mixer, in one layer upon another and that the thickness of filler and fine fraction is limited by the penetration of the bituminous liquid in accordance with the process of the invention that imply the binding to the surface of the coarse fraction, first a layer of bituminous liquid, and thereafter through penetration by the layer of bituminous liquid, bind a layer of filler, and further a layer of fine fraction is spread on the top of the layer of filler, and bond by the penetration of the bituminous liquid in a combined suspension where both the filler and fine fraction are part of the closed volume of bituminous liquid with the consequence of that pressure and tension forces on paving are resisted by the hydrostatic function of the, through the skeleton of aggregate, continuous bituminous liquid.

Description: INVENTION CONCERNING PRODUCTION OF ASPHALTMIX The following inventi on is based on the knowledge that a relati on exist between two, in principle, different mixing methods, and the change in the influence of the surface area and volume of the aggregate on the physical chemistry of the bi tuminous liquid in the mixing of asphalt mixes, and that the durabil ity and the cli mate resistance of the finished products are functions of this existing relation. The major difference in the mixing methods is that the first principle leads to an increased liquid content, in the quantity of particles, in the mixer, while the second principle leads to an increase in the content of particles in the liquid already placed in the mixer. The i nvention, as wel l as the patent EP A2 0073 181 for producti on of asphal t mix is based on mixing by the second principle. A principl e mixing method must be f urnished with detail s i n order to be applicabl e. The invention differs for this reason not in principle from the mixing method in accordance with patent nr EP A2 00731 81. The difference is revealed in the details of the principle for application of the invention, determined by the result aimed at. The goal has grown when producing mix with the patented details. The reason for the invention is that at the discharge of the filler in patent nr EP A2 0073181 , and other known processes the filler is not spread in a layer over the surface of the bi tumi nous liquid on the flowing coarse fraction, but in the quickest way discharged into the mixer to be distributed and penetrated through forced mixing by agitation of the materials. Further, the fine fraction is added after the fil ler and the bituminous liquid have devel oped the suspensi on, with the result that the fine fraction incalpsulates in the devel oped suspensi on of filler. These two detail s in the patented mixi ng method have shown to prevent the development of a combined suspension of the f iller and the fine fraction. The prerequest for having both filler and fine fraction dispersed in a combined liquid volume, is that the liquid penetrates both materials in one step. In order that the layer of bituminious liquid shall penetrate both filler and fine fraction, in one step the materials shall be spread in even layers over the surface of the flowing coarse fraction in the mixer. To accomplish this, the inlets are equipped for opti mizati on of interval of time between di scharges of the different materials i nto the mixer and for optimization of rates of flow at spreading, in layers, the filler and the fine fraction over the surface of the coarse fraction in accordance with the invention, to first put a layer of bituminous liquid over the surface of the coarse fraction and then powder the layer of bituminous liquid and, through penetration, bind a layer of filler after which the fine fraction is distributed in a new l ayer through further penetration of the bituminous liquid, whereby the bituminous liquid through the layers of materials unites the fill er, the fine fraction and the coarse fraction in a closed volume of liquid, a condition at which the paved mix resist pressure and strain by the hydrostatic function of the bituminous liquid obtained when the liquid is continuous through the skeleton of the aggregate. The problem wi th asphalt pavi ngs is their tendency to form tracks and cracks. When fi ller and fine fraction both are parts of the closed li quid volume, pressure and tensil e stress are distributed by the hydrostatic functi on of the liquid. The distribution of pressure by the gl ue phase protects the pavi ng agai nst overload and f orming of tracks at hi gh temperatures, and the toughness of the gluephase protects the paving from forming of cracks at low temperatures. Appendi x Figure l b) shows asphalt mix in lack of hydrostatic pressure distributi on. The deformation in the specimen of test is governed by the force of gravitation. Fi gure l a) shows asphal t mix with hydrostatic pressure distributi on and toughness. The continuous resi stance against elongati on during deformation shows that the bituminous liquid is a cl osed volume. The invention was discovered in use of the patent nr EP A2, 0073181 , when it occured that the choi ce of time intervals has made patent nr EP A2, 0073181 to a borderline case of the invention. Knowledge of optimizing the process has not been available as one has worked in accordance with the hypothesi s that the larger volume of the suspension with filler must be developed before the fine fraction can be accomondated in the li quid and, at the same time, with disregard to the demand that the fill er must be spread over the flowing surface of bituminous liquid at discharge into the mixer, in the inventi on obtained by abandoning the uncontrolled discharge i nto the mixer by the known mixing processes, for a discharge i nto the mi xer by controlled flow rate, in order to obtain an optimi zed distribution of the filler over the l ayer of the bituminous liquid. Through the distribution, the filler lead the penetration of the bituminous liquid through the layer of the fine fracti on material resulting in that both the filler and the fine fraction become part of the same volume of suspension. The invention is a complement to patent nr EP A2, 0073181 , that has been devei opd to secure the properties of the process of mixing obtained when the liquid of mix is a closed volume. The process of the invention, where the bituminous liquid first is distribu- ted on the surface of the coarse fraction, thereafter powdered wi th filler and then the particl es of the fine fraction are di stributed over the surface, before the bituminous liquid has broken through the layer of filler, causes that it shall be used not only on bach plants but al so on asphalt plants with continuous working mixers and on drum mixers.

Claims: Claim 1 Process for production of asphalt mix that includes at least 1) aggregate divided in a coarse and a fine fraction, 2) filler and 3) flowing bituminous binder is ch a ra c te ri z ed by that the bitumen, the filler and the fine fractions are spread over and by the surface of the flowing coarse fraction in the mixer in one layer opon the other, first binding a layer of bituminous liquid and thereafter, through penetration of the layer of bituminous liquid, binding a layer of filler after which a further layer of the fine fraction material is spread over the layer of filler and thus becomes enclosed through further penetration of the bituminous liquid in a combined suspension where both the filler, the fine fraction and the coarse fraction are part of the closed liquid volume whereby pressure and tensile force on the paving are resisted by the hydrostatic function of the continuous bituminous liquid through the skeleton of aggregate particles . Claim 2 Process in accordance to claim l is c h a ra c t e ri z ed by that the penetration of the bituminous liquid through the filler and the fine fraction develops in one step through spreading, in two layers, the filler and the fine fraction materials over the surface of bituminious liquid, bond to the surface of the flowing coarse fraction in the mixer. Claim 3 Process in accordance to claim l is cha racteri zed by that the filler is spread in a layer over the layer of bituminous liquid on the surface of the coarse fraction. Claim 4 Process in accordance to claim 1 is cha ra cte ri zed by that the fine fraction is spread in a layer over the surface of the coarse fraction, coated by the bituminous liquid that penetrates a layer of filler. Claim 5 Process in accordance to claim l is c h a ra c t e r i z ed by that the content of fine fraction in mix is determined by the volume of fine fraction materials that can be accommodated in the closed volume of bituminous liquid. Claim 6 Device on the asphalt plant for application of the process where the distribution of the filler and the fine fraction is obtained by the flowing coarse fraction, in accordance to claim 1,is c haracte ri z ed by that the inlets; gates, screws et., are equipped for choice of optimum intervals of time and flow rates for the inflow of the filler and the fine fractions into the mixer to be used for optimizing the distribution of the materials in layers over the fl owing coarse fraction at the respective materials discharged into the mixer.

Inventors: OHLSON KARL GUNNAR, OHLSON, KARL, GUNNAR
Applicants: OHLSON KARL GUNNAR, OHLSON, KARL, GUNNAR
Application year: 1995
Main classification: C10C3
IPC codes: C10C3, E01C19