theory on frost action,occurence,causes,effects

1. SEMINAR ON FROSTSEMINAR ON FROST
ACTIONACTION
ByBy
Shruthi.N.PShruthi.N.P
LecturerLecturer
GPT,HariharaGPT,Harihara

2. INTRODUTIONINTRODUTION
►The climatic variations cause following majorThe climatic variations cause following major
effectseffects
 Frost actionFrost action
 Variation in moisture conditionVariation in moisture condition
 Variation in temperatureVariation in temperature

3. Cont..Cont..
►The pavement performance is very muchThe pavement performance is very much
affected by the variation in moisture and theaffected by the variation in moisture and the
frost.frost.
►This is mainly because of the variation inThis is mainly because of the variation in
stability and the volume of the subgrade soilstability and the volume of the subgrade soil
due to these two effects.due to these two effects.
►Variation in temperature generally affects theVariation in temperature generally affects the
pavement materials like bituminous mixes andpavement materials like bituminous mixes and
cement concrete.cement concrete.

4. FROST ACTIONFROST ACTION
►The effect of rainfall on pavementThe effect of rainfall on pavement
performance has not received as muchperformance has not received as much
attention as that of frost actionattention as that of frost action
►Frost action refers to the adverse effects due toFrost action refers to the adverse effects due to
frost heave,frost melting or thaw and alternatefrost heave,frost melting or thaw and alternate
cycles of freezing and thawing.cycles of freezing and thawing.
►Frost damage to pavements and theirFrost damage to pavements and their
subgrades occurs in two distinct phases.subgrades occurs in two distinct phases.

5. First phaseFirst phase
It occurs during winter season when air
temperatures are below freezing for sustained
periods of time
FROST HEAVE: Heave means the lifting of the
surface of soil due to expansion of subgrade by
absorption of water in clayey soils and formation of
ice between soil grains to a considerable depth.

6. Formation of heaveFormation of heave
Water held in subgrade soilSUBGRADE SOIL

7. ContCont....
ICE LENSES
TEMP < 4’C
SUBGRADE
SOIL
Raising of pavement
surface

8. Cont..Cont..
pavement
subgrade
a
pavement
Ice lenses fed by capillary water
Frost table
b
By water table
Frost heave
NORMAL CONDITION FROST HEAVE
Water table

9. Second phaseSecond phase
►It occurs towards the end of the winter season.It occurs towards the end of the winter season.
►Subsequent increase in temperature would resultSubsequent increase in temperature would result
in melting or thawing of the frozen ice crystalsin melting or thawing of the frozen ice crystals
and softens the road bed.and softens the road bed.

10. ContCont....
►FROST BOILFROST BOIL:: If the pavement is of a flexibleIf the pavement is of a flexible
and traffic is allowed to use the road while theand traffic is allowed to use the road while the
subgrade is in this condition,the wheels ofsubgrade is in this condition,the wheels of
vehicles easily break through the pavement andvehicles easily break through the pavement and
churn up the softy soupy layers of soilchurn up the softy soupy layers of soil
immediately below.immediately below.

11. BASIC CONDITIONS FOR GROWTH OF ICEBASIC CONDITIONS FOR GROWTH OF ICE
LAYERSLAYERS
The ice layers or lenses which causes highway andThe ice layers or lenses which causes highway and
airport surfaces to heave, grow in the soil inairport surfaces to heave, grow in the soil in
essentially the following manner…essentially the following manner…
 The frost line penetrates downwards, small volumesThe frost line penetrates downwards, small volumes
of water in the soil pores freeze.of water in the soil pores freeze.
 This action, in effect,dries the soil in the region of theThis action, in effect,dries the soil in the region of the
ice formation,because the frozen water is no longerice formation,because the frozen water is no longer
available to satisfy the attraction of the soil foravailable to satisfy the attraction of the soil for
capillary water..capillary water..
 Since drying a soil decreases its matric potential,Since drying a soil decreases its matric potential,
water from below where the potential is greater,tendswater from below where the potential is greater,tends
to flow upward towards this new created region ofto flow upward towards this new created region of
low potentiallow potential..

12. ContCont....
 This water also freezes when it reaches the frost line.This water also freezes when it reaches the frost line.
 As it freezes, the newly formed ice attaches to theAs it freezes, the newly formed ice attaches to the
originally minute ice particles, causing them to increaseoriginally minute ice particles, causing them to increase
in thickness in the downward direction.in thickness in the downward direction.
 Thus the heave producing ice layers grow, being fed byThus the heave producing ice layers grow, being fed by
capillary water from below and process continues.capillary water from below and process continues.
 The sum of the thickness of all the ice layers that formThe sum of the thickness of all the ice layers that form
is the amount by which the surface heaves.is the amount by which the surface heaves.

13. Three basic conditions must exist inThree basic conditions must exist in
order for ice layers to form and grow inorder for ice layers to form and grow in
thicknessthickness
►Freezing temperatures in the soil.Freezing temperatures in the soil.
►A reservoir of ground water sufficiently close toA reservoir of ground water sufficiently close to
the frost line to feed the growing ice layers.the frost line to feed the growing ice layers.
►Soil material having favourable characteristicsSoil material having favourable characteristics
for rapid movement of capillary water upwardfor rapid movement of capillary water upward
from the water table.from the water table.

14. FACTORS INFLUENCING FROST ACTIONFACTORS INFLUENCING FROST ACTION
 Frost susceptible soilFrost susceptible soil
 Depressed temperature below freezing pointDepressed temperature below freezing point
 Supply of waterSupply of water
 covercover

15. EFFECTS OF FROST ACTIONEFFECTS OF FROST ACTION
►Frost heave:raising in pavement surfaceFrost heave:raising in pavement surface
►Frost melting and thawing: decrease in loadFrost melting and thawing: decrease in load
carrying capacity of sub grade soil.carrying capacity of sub grade soil.
►Causes undulations and considerable damages toCauses undulations and considerable damages to
the pavement.the pavement.

16. DEPTH OF FROST PENETRATIONDEPTH OF FROST PENETRATION
►The performance of pavements in frost affectedThe performance of pavements in frost affected
regions depends to a large degree on the depth ofregions depends to a large degree on the depth of
frost penetration.frost penetration.
►Prediction of the max depth of frost can bePrediction of the max depth of frost can be
accomplished in several ways, includingaccomplished in several ways, including
correlation of field penetration data withcorrelation of field penetration data with
temperature data and theoritical formulas andtemperature data and theoritical formulas and
charts.charts.

17. CONTCONT....
►Several formulas have been presented forSeveral formulas have been presented for
predicting depth of frost penetration.predicting depth of frost penetration.
►STEFAN’S EQUATION:It is derived bySTEFAN’S EQUATION:It is derived by
equating the fundamental equation of heat flowequating the fundamental equation of heat flow
and storage.and storage.
►ASSUMPTION: Only heat flow that need to beASSUMPTION: Only heat flow that need to be
considered is that represented by the latest heatconsidered is that represented by the latest heat
of fusion of the soil water, time T is converted toof fusion of the soil water, time T is converted to
days.days.

18. ContCont....
►Z=Z= 48KF
L
WHERE,WHERE,Z= DEPTH OF PENETRATION IN A HOMOGENOUS MASS(ft)Z= DEPTH OF PENETRATION IN A HOMOGENOUS MASS(ft)
K=thermal conductivity(Btu’s/ square foot/ degree F, per foot. Per hr)K=thermal conductivity(Btu’s/ square foot/ degree F, per foot. Per hr)
F=degree daysF=degree days
L=volumetric heat of latest fusion(Btu’s/ cubic foot)L=volumetric heat of latest fusion(Btu’s/ cubic foot)

19. Objections to silty soilsObjections to silty soils
 The poorest soils from the stand point of frostThe poorest soils from the stand point of frost
damage are the soils that are frost prone those aredamage are the soils that are frost prone those are
 sufficiently fine grained (to exert moderately highsufficiently fine grained (to exert moderately high
capillary forces tending to lift water above a watercapillary forces tending to lift water above a water
table).table).
 Sufficiently coarse grained (to have a high rate ofSufficiently coarse grained (to have a high rate of
capillary conductivity)capillary conductivity)
 Soil of this kind will transmit relatively largeSoil of this kind will transmit relatively large
quantities of water in a relatively short time to feedquantities of water in a relatively short time to feed
growing ice lenses.growing ice lenses.
 Uniformly graded soils that contain >10% of particlesUniformly graded soils that contain >10% of particles
smaller than 0.02mm and fairly well graded soilssmaller than 0.02mm and fairly well graded soils
containing more than 3% of this size should becontaining more than 3% of this size should be
looked upon with suspicion whenever encountered inlooked upon with suspicion whenever encountered in
a soil survey.a soil survey.

20. Measures to prevent frost actionMeasures to prevent frost action
►Installation of proper surface and sub surfaceInstallation of proper surface and sub surface
drainage system.drainage system.
►Construction of layers of pavement upto theConstruction of layers of pavement upto the
desired depth.desired depth.
►Using granular and non frost susceptibleUsing granular and non frost susceptible
material to resist adverse climatic conditions.material to resist adverse climatic conditions.
►Providing the suitable capillary cut offProviding the suitable capillary cut off
►By soil stabilizationBy soil stabilization

21. REFERENCESREFERENCES
►Highway engineering - S.K.Khanna &Highway engineering - S.K.Khanna &
C.E.G.JustoC.E.G.Justo
►Soil engineering – Merlin.G.SpanglerSoil engineering – Merlin.G.Spangler
►Principle of pavement design – yoder,E.JPrinciple of pavement design – yoder,E.J

22. THANK YOUTHANK YOU