The Uses and Value

of Lime inof Lime inRoad Construction

Presented byPresented by

Carmeuse North America

Added Value Applications

• Lime meets the challenges facing both the road designer, and the

i h fcontractor in the areas of:

– Soil Stabilization and Modification– Asphalt treatment and recycling

Lime in Soil Modification

• Soil Modification –Short term and immediate benefits:

– Plasticity reduction– Drying– Swell reduction– Improved Stability and Compaction

S lid W ki Pl tf– Solid Working Platform

• Saves time and money!

Lime in Soil Stabilization Mix Designs

• Fine Soils and Clays (typically PIs 15 and above)

– Handling improvements as soil modification– Substantial Increase in CBR Resilient Modulus– Continued Strength Gain with Time– Long Term Durability in very adverse conditions– Long Term Durability in very adverse conditions– Very Cost Effective– Proven Approach

• Lime-Flyash treatment applicable for Sandy /Silty soilsSandy /Silty soils

• Lime use in asphalt recycling FDR (Full Depth Reclamation)

Lime Based Mix Designs forDifferent Soil TypesDifferent Soil Types

avel

sel

san

d

mix

ture

s

clay

mix

ture

s

lly s

ands

,

velly

s ture

s

s, ro

ck

s um

y cl

ays,

clay

s of

ilts,

ity, f

at c

lays

igh

plas

ticity

orga

nic

soils

SoilType

aded

gra

vels

and

gra

ures

, litt

le o

r no

fines

ed g

rave

ls a

nd g

rave

ittle

or n

o fin

es

els,

gra

vel-s

and-

silt

m

avel

s, g

rave

l-san

d-c

ed s

ands

and

gra

vefin

es

ded

sand

s an

d gr

ave

or n

o fin

es

s, s

and-

silt

mix

ture

s

ands

, san

d-cl

ay m

ixt

silts

, ver

y fin

e sa

nds

or c

laye

y fin

e sa

nds

clay

s of

low

to m

edi

grav

elly

cla

ys, s

andy

lean

cla

ys

lts a

nd o

rgan

ic s

ilty

city silts

, mic

aceo

us o

r eo

us fi

ne s

ands

or s

is cl

ays

of h

igh

plas

tic

ays

of m

ediu

m to

hi

ck, a

nd o

ther

hig

hly

o

UnifiedGroup Symbol GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT

Poor

ly g

rasa

nd m

ixtu

Wel

l gra

dem

ixtu

res,

l

Silty

gra

v e

Cla

yey

gra

Wel

l-gra

delit

tle o

r no

Poor

ly g

rasa

nds,

littl

e

Silty

san

ds

Cla

yey,

sa

Inor

gani

c s

flour

, silt

y

Inor

gani

c c

plas

ticity

, gsi

lty c

lays

,

Org

anic

si

low

pla

stic

Inor

gani

c s

diat

omac

eel

astic

silt

s

Inor

gani

c c

Org

anic

cl

Peat

, mu c

AASHTOGroupClassification

Group Symbol

A-1-a A-1-a A-1-b A-1-b A-1-bA-1-b

orA-3

A-2-4or

A-2-5

A-2-6or

A-2-7A-4 A-6 A-4 A-5 A-7-6 A-7-5 A-8

RecommendedAdditives

LIME (Stabilization & Modification)

LIME PLUS TYPE “F” Coal Fly Ash (Stabilization)

Lime Reacts Chemically with Claysto Alter Molecular Interactionsto Alter Molecular Interactions

Untreated clays have amolecular structure similar to Flocculation/Agglomerationmolecular structure similar to

some polymers, and give plastic properties. The structure can

trap water between it’s molecular layers, causing volume and Unstabilized Clay Particlesy , g

density changes.

In treated clays Calcium atoms (from Lime) have replaced Sodium and

Flocculation/Agglomeration

Hydrogen atoms producing a soil with very friable characteristics

On-going reaction with available Silica d Al i i th il f l

Clay after flocculation / Agglomeration

and Alumina in the soil forms complex cementatious materials (the POZZALONIC effect.

Pozzolanic Reactions Using LimeEssential to the treatment of clay soils

On-going reaction with available Silica and

Pozzolanic Reaction

Essential to the treatment of clay soils

Alumina in the soil forms complex cementitious

materials (the

Ca (OH )2

Ca (OH )2

(POZZOLANIC effect.)

Calcium HydroxideCementitious

Ca (OH )2

Ca (OH )2

Clay Particle

From lime or cementMaterial from pozzolanic reactions[CSH and CAH]

Lime Reacts Chemically with Flyash to provide Cementatious Resultto provide Cementatious ResultEssential to the treatment of non-clay soils and aggregates

Reactions between lime and the Silica and Alumina in

flyash form complex titi t i l

Pozzolanic Reaction

Ca (OH )2

cementitious materials

Lime and Flyash provide a filler for larger particles of Clay Particle

Ca (OH )2

g psand or gravel based soils

Calcium HydroxideFrom lime or cement

CementitiousMaterial from pozzolonic reactions

Ca (OH )2

Ca (OH )2

[CSH and CAH]

Results of Lime Treatment:Immediate Impact on Plasticity Workability

Drying: The water content is reduced from

Immediate Impact on Plasticity, Workability, and Load Bearing Capacity

Before Treatment

PL Wn LL

Wn to W’nPlasticity: Treatment with lime displaces the solid range to the right. This enables the soil to accept a higher water content while remaining solid The plasticity index PI = LL-PL

Liquid RangePlastic RangeSolid Range

PI

Increasing Water Content

solid. The plasticity index PI = LL PL is reduced.

After Treatment

(PI)’

(LL)’W’n (PL)’70

60

CB

R % UNTREATED

0.5 % LIME

3% LIME

Increase in carrying capacity after liming: After 2 hours with an initial water content of 14% the CBR index increased from 9 to 30 (0 5% lime added) and 70 (3%

40

30

20

15

10

9

8

30 (0.5% lime added) and 70 (3% lime added) respectively

4

3

2

0W %

0 12 14 16 18 20

Lime in Soil Modification: Preparing the sitePreparing the site

• Dry up the site and keep on working

• Great working platformf h hifor heavy machinery

• Makes non-workable clays into workableclays into workable soils in minutes

Lime in Soil StabilizationCompressability from initial curing continueCompressability from initial curing continue

The Pozzolanic reactions from Lime treatment

1.0

Mpa

)

6% Caofrom Lime treatment continue, allowing the base to gains strength and reducecompressability.

0.8

0.6

Rc

(M 6% Cao

4% CaO

The availability of small amounts of excess lime provide “self-healing” (or

0.4

2% CaO

1% CaO

provide self healing (or “Autogenous healing”) of cracks caused by repeated freeze-thaw cycles over time.

0.2

0.0Age in days

0% CaO

1 28 360

Cost Effective Solution to Stabilizationto Stabilization

• Lower Construction Costs– Makes in-place materials usable– Eliminates costs to remove and dispose– Eliminates cost associated with re-fill materials

• Lower Lifetime Costs– Lower maintenance costs through better

resistance to water and freeze-thaw effects– Extended lifetime before replacement required

Cost Effective Solution to StabilizationComparison of Lime to Alternative MaterialsComparison of Lime to Alternative Materials A case study* – PA Turnpike Somerset Section, 21km long, 23.6m wide. (* Bashar Seksinsky Jianchao TRB Presentation January 2000)(* Bashar, Seksinsky, Jianchao, TRB Presentation January 2000)

Natural Sub-grade Lime Stabilized Sub-grade Design Methodology

Base Thickness* (mm)

Project Cost** (MM$)

Base Thickness* (mm)

Project Cost*** (MM$)

Resilient Modulus Calculation 730 28.2 490 21.6

CBR Calculation 680 26 1 510 22 1CBR Calculation

680 26.1 510 22.1

Layer Structural Coefficient 680 - 550 23.7

*R i d B Thi k t t D i R i t

20% Cost Saving*Required Base Thickness to meet Design Requirements**Includes $2.3 MM for removal of existing pavement***Includes $2.3 MM for removal of existing pavement plus

$2.3 million for lime stabilization

Lime (or Lime-Flyash) in asphalt FDR (Full Depth Reclamation)in asphalt FDR (Full Depth Reclamation)

• Easy to apply in FDR processFDR process

• Provides Pozzolanic effect to provide strength to thestrength to the reclaimed base material

Working Direction

• Water resistance

• Strength gain over time

Old roadsurface

New base mixtureready for compaction

Lime added

Variable mixing chamber with milling and mixing rotor

time

• Autogenous healing of cracks

Summary – Areas of Application for Lime Stabilizationfor Lime Stabilization

• Base StabilizationRoads (all grades)– Roads (all grades)

– Parking lots / Public areas– Upgrades marginal base material

ki i blmaking it usable

• Asphalt FDR• Structural Fills and Embankments• Structural Fills and Embankments• Site Preparation