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Frost modelling and pavement temperatures: Summer pavement temperatures and frost modelling. Licentiate thesis
Swedish National Road and Transport Research Institute.
2001 (English)Report (Other (popular science, discussion, etc.))
Abstract [sv]

Temperature and moisture are very essential parameters

when describing the condition of a

pavement. In most cases, a high moisture content

involves a decreased bearing capacity and,

consequently, a shorter durability of the pavement. A

frozen pavement has a greater bearing

capacity than the corresponding construction in spring

or late autumn. However, the freezing

itself also implies strains to the pavement, as it

heaves to different extent and in different

directions in connection with the frost heave. The

properties of an asphalt concrete pavement

vary dramatically according to temperature. A cold

asphalt concrete is hard, stiff and brittle,

and therefore, cracks easily occur, whereas its

bearing capacity decreases at high temperatures

as softening progresses.

A numerical model has been developed for calculation

of the temperatures in a road pavement

during summer condition, especially emphasizing the

asphalt concrete. Further, in order to

also model temperatures and other conditions,

occurring during winter conditions in the

pavement, such as frost heave, a frost heave model has

been developed. The aim of this is to

gain a better insight into the freezing process of a

road structure. The model also provides an

efficient tool for a better understanding of important

factors related to frost depth and frost

heave. In the present work, numerical analysis of

frost heave and frost front propagation has

been performed and compared with some field


Furthermore, equipment for freezing tests in

laboratory has also been developed. Experiences

from such tests and field measurements have been used

when developing the numerical model

for the freezing of pavements. At the laboratory

freezing tests, a special interest has been

devoted to heave rate, water intake rate and cooling

rate. The experiences, obtained from both

the laboratory tests, as well as the field

observations, have been compared to what has been

reported in literature.

Temperatures obtained from the numerical model for

summer temperatures have turned out to

correspond well to measurements of pavement

temperatures on three different levels below

the road surface on a road west of Stockholm, Sweden.

Calculated temperatures were also

compared with temperatures calculated by using a model

presented by SUPERPAVE (i.e. the

asphalt binder specification, developed under the

Strategic Highway Research Program

(SHRP) USA). This model gives the highest temperature

of asphalt concrete during daytime.

According to the opinion of the author it is found

that SUPERPAVE uses an erroneous

assumption that there is equilibrium when the highest

temperature is reached in the pavement

on a hot summer day. This, of course, leads to an

overestimation of the temperature, which is

compensated in SUPERPAVE by assuming that the highest

temperature is reached at a

relatively high wind velocity of 4.5 m/s instead of at

feeble winds, which is more realistic

according to the author.

Results from the frost model show a good agreement

with field measurements of

temperatures, frost depth and frost heave.

The freezing tests in laboratory have shown, that a

strong frost heave can exist without

addition of external water to the samples. The natural

water content is, consequently,

sufficient to provide enough water for the heave. This

“in-situ” water can be redistributed the structure

thus providing water to the frozen portion of the

profile to cause significant frost

heave. Frost heave caused by a process like this, is

not bound to uptake of external water,

which normally is assumed in the relevant literature.

Frost heave in freezing tests is often

explained by 10 % volume expansion of the freezing

water, which is sucked up by samples

during the test.

Place, publisher, year, edition, pages
Linköping: Statens väg- och transportforskningsinstitut., VTI särtryck 344 , 2001.
VTI särtryck, ISSN 1102-626X
Keyword [en]
English, Sweden, Frost, Mathematical model, Pavement, Temperature, Summer, Flexible pavement, Heaving, Depth, Equipment, Laboratory, Moisture, Calculation
Research subject
Road: Highway design, Road: Freeze-thaw
URN: urn:nbn:se:vti:diva-4532OAI: diva2:673356
Available from: 2013-12-03 Created: 2013-12-03 Last updated: 2013-12-03

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