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Russian Journal of Applied Chemistry,Vol. 75, No. 7, 2002, pp. 119831199. Translated from Zhurnal PrikladnoiKhimii, Vol. 75, No. 7,2002, pp. 122131222.Original Russian Text CopyrightC 2002 by Rozental’, Ivanova.

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Prediction of Properties of Asphalt Oil in Asphaltic Concrete

D. A. Rozental’ and E. S. Ivanova

St. Petersburg State Technological Institute, St. Petersburg, Russia

Received February 26, 2002

Abstract-Evolution of characteristics of asphalt oil in contact with mineral ballast in the course of long-termstorage of asphaltic concrete at room temperature is studied. Data on the effect of the preparation time of mixasphalt on the structure and properties of asphalt oil in asphaltic concrete are analyzed.

Asphalt oils are widely used in road construction asmaterials for asphaltic concrete pavement. Asphaltoils in asphaltic concrete play a role of an organicbinder for the mineral fraction. When manufacturingasphaltic concrete, asphalt oil is mixed with mineralballast at 160oC for 20 min. Physical interaction ofasphalt oil with the mineral filler is accompanied byformation of adsorption layers of the binder on thefiller grains. This process includes many adsorption3

desorption stages, until reaching the equilibrium.This is a selective process, resulting in extraction ofthe most readily adsorbed components from asphaltoil, which, in its turn, distorts the thermodynamicequilibrium in the colloidal system of asphalt oil.As a result, the system is transformed, approachingnew equilibrium state corresponding to given condi-tions. Finally, transformation of the asphalt oil struc-ture changes its characteristics.

The factors influencing adsorption of asphalt oilon the mineral filler surface are as follows [133]: heat-ing temperature, heating timet, the kinds of mineralballast and asphalt binder, and, finally, the ballastgrading.

The goal of this work was to predict the evolutionof characteristics of asphalt oil in asphaltic concrete.Therefore, we studied the effect of the time of heatingof mix asphalt at 160oC on the adherence of asphaltoil to mineral ballast. As mineral ballast we usedgranite with a grading of 335 mm. The heating timewas varied from 20 min to 4 h. In experiments weused BND 40/60 asphalt oil produced by the KINEFProduction Association, Limited Liability Companyfrom a mixture of West Siberian oils. The adhesionwas measured by the hot centrifugation method [4],followed by determination of the performance charac-teristics of the extracted product.

With increasing heating time, the amount of as-

phalt oil retained on the mineral ballast surface in-creases, saturating att = 3 h (see figure).

Evolution of the performance characteristics (pene-tration P25 and softening pointTs) of asphalt oilextracted from mix asphalt by centrifugation is givenbelow.

t, h 0 1/3 2/3 1 2 3 4P25, 59 58 55 34 32 30 28mm00.1Ts, oC 51 54 56 67 70 72 73

With increasingt, the softening point considerablyincreases, and the penetration abruptly decreases.At t = 3 h these parameters approach their saturatedvalues.

The observed evolution of the softening point andpenetration is well consistent with data on the adhe-sion of asphalt oil to the mineral ballast, suggestingthat establishment of the adsorption equilibrium inmix asphalt takes about 3 h.

In asphaltic concrete in service, asphalt oil occursin the cold state. Our results obtained at room tem-perature allow prediction of the behavior of asphalt oilin asphaltic concrete pavements.

A, wt %

t, h

Effect of the heating timet of mix asphalt at 160oC onthe adherence of asphalt oil to mineral ballastA.

RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 7 2002

PREDICTION OF PROPERTIES OF ASPHALT OIL IN ASPHALTIC CONCRETE 1199

Evolution of characteristics of asphalt oil in storage afterheating of mix asphalt for 1 hÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄStorage³ Adherence,³

Ts, oC³ P25,

time ³ wt % ³ ³ mm00.1ÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄ

0 ³ (27)* ³ 67 (72) ³ 34 (30)1/3 ³ 12 (9) ³ 49 (51) ³ 54 (52)2/3 ³ 12 (9) ³ 51 (55) ³ 52 (42)1 ³ 12 (9) ³ 52 (55) ³ 48 (36)2 ³ 10 (10) ³ 55 (56) ³ 42 (34)3 ³ 8 (10) ³ 56 (57) ³ 39 (33)4 ³ 8 (25) ³ 57 (59) ³ 38 (33)5 ³ 8 (25) ³ 57 (61) ³ 37 (32)6 ³ 8 (25) ³ 58 (63) ³ 37 (32)7 ³ 8 (25) ³ 58 (63) ³ 37 (32)

ÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄ* Data for mix asphalt after 3-h heating are given in paren-

theses.

We studied the evolution of characteristics of as-phalt oil separated by hot centrifugation from mixasphalt after long-term storage (from 10 days to7 months) at room temperature (18oC). The results aregiven in the table.

Initially mix asphalt was heated at 160oC for 1 and3 h. The results show that establishment of the adsorp-tion equilibrium requires at least 3-h heating. Thus,

it is seen how the initial heating time influences thecharacteristics of asphalt oil in asphaltic concrete.

The temperature drop from 160 to 18oC in mixasphalt initiates a considerable change in the structureand characteristics of asphalt oil (see table). However,in the course of subsequent storage of mix asphalt inthe cold state, these changes decay as a result of alarge number of adsorption3desorption events. It fol-lows from the table that the equilibrium establishedafter heating for a fixed time is practically identical tothat after the subsequent storage at room temperature.Therefore, data on evolution of characteristics ofasphalt oil in the course of heating in contact withmineral ballast allows prediction of the behavior ofthis material in asphaltic concrete.

REFERENCES

1. Rozental’, D.A. and Syroezhko, A.M.,Khim. Tekhnol.Topl. Masel, 2000, no. 4, pp. 41343.

2. Rozental’, D.A.,Zh. Prikl. Khim., 1995, vol. 68, no. 7,pp. 105731066.

3. Rozental’, D.A., Golovanova, T.A., and Narubina, S.P.,Khim. Tekhnol. Topl. Masel, 1998, no. 4, pp. 48349.

4. Khudyakova, T.S., Rozental’, D.A., Mashkova, I.A.,et al., Khim. Tekhnol. Topl. Masel, 1987, no. 6, pp. 35336.