New DGBR TI No 14

8/11/2019 New DGBR TI No 14

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DIRECTORATE GENERAL BORDER ROADS

TECHNICAL INSTRUCTION NO 14(REVISION – 2014)



Foreword1. DGBR Technical Instruction No.14 deals with design of flexiblepavement. For the first time This Technical Instruction was issued videDGBR letter No.69242/TI.DGBR/DTP Coord dated 08 Aug 1993 andfurther revised in 1990 and 2003. During 2012 TI was re-printed withminor revision.TI-14 is supplemented by the standards laid down byIndian Roads Congress and MORT&H specification which are beingadopted for Design of Flexible Pavement in BRO. This TechnicalInstruction has now been revised based on IRC: 37- 2012” TentativeGuidelines for design of Flexible Pavement” and MORT&H Specificationsfor Roads & Bridges (Fifth Revision).

2. During last two decades the traffic pattern on Indian roads haschanged significantly and so has technology. The volume of vehicles has

increased manifold and tandem, tridem and multi axle loads are common. Ac co rd ing ly at ten tio n is fo cu se d on fa ti gue re si stance bitumi nous mi xeswith viscosity binders for heavy traffic with a view to construct highperformance long life bituminous pavements.

3. It has been also experienced by R-56 Committee of IRC thatconventional construction materials like stone aggregates are becomingprogressively scarce due to environment concerns and restrictedquarrying. As such use of local, recycled and engineered marginalaggregates as well as use of new forms of construction materials such asStone matrix asphalt, modified bitumen, foamed bitumen, warm mix



INDEX

S No Chapter Page No

1 Introduction

2 Component of Flexible Pavements

3 Traffic Design

4 Soil Parameters

5 Principle of Flexible Pavement Design

6 Composition of Pavement7 Pavement Design Procedure

8 Pavement Design Catalogues

9 Internal Drainage in Pavements

10 Pavement Design in Frost Affected Areas11 Design of Pavement for Expansive Soils



ABBREVIATIONS

AAAT - Average An nua l Ai r Tem pe ra tu re AAPT - Average An nua l Pa ve ment Te mper at ure

AMAT - Average Mo nthl y Ai r Te mpera tu re

AMPT - Average Mo nthl y Pavement Tem pe ra tu re

AASHTO - Ameri ca n Asso ci ati on of St ate Highwa y andTransportation Officials

ASTM - Ameri ca n Soc iety of Tes ti ng and Mate ri al s

AUST ROADS - As soci at ion of Au st ra lia n and New Ze ala ndRoad Transport and Traffic Authorities.

BC - Bituminous Concrete

BIS - Bureau of Indian Standards

BM - Bituminous MacadamCs - Spacing of Transverse Cracks

CBR - California Bearing Ratio

CFD - Cumulative Fatigue Damage

CTB/CT - Cement Treated Base – Includes all type ofCement/Chemical stabilized bases

DBM - Dense Bituminous MacadamE - Elastic Modulus of Cementitious Layer

GB Gran lar Base



N f - Cumulative No. of Repetitions for Fatigue Failure

N R - Cumulative No of Repetitions for Rutting Fatigue

PC - Premix Carpetq i - Water Infiltration Rate Per Unit Area

SAMI - Stress Absorbing Membrane Interlayer

RAP - Reclaimed Asphalt Pavement

RF - Reliability Factor

SDBC - Semi-Dense Bituminous Concrete

SD - Surface Dressing

SDP - State Domestic Product

UCS - Unconfined Compressive Strength

V a - Volume of Air Voids

V b - Volume of Bitumen

VDF - Vehi cl e Da mage Fa ctor

VG - Vi sc os ity Gra de

W p - Width of Pavement Subjected to Infiltration

W c - Length of Transverse Cracks

WBM - Water Bound Macadam

WMM - Wet Mix Macadam

ε t - Horizontal Tensile Strain



DGBR TECHNICAL INSTRUCTION NO-14

SPECIFICATIONS FOR FLEXIBLE PAVEMENTFOR ROADS IN BRO

1. INTRODUCTION

1.1. DGBR Technical Instruction No.14 deals with design of flexiblepavement for roads. Earlier the Pavement design was based on CaliforniaBearing Ratio (CBR) of sub grade and traffic in terms of number ofcommercial vehicle (more than 3 ton laden weight). In later revisiondesign traffic was considered in terms of cumulative number of equivalentstandard axle load of 80kN in millions standard axle (msa) and designchart were provided for traffic up to 30 msa using an empirical approach.

1.2 IRC: 37-2001 was revised during 2001 when pavements were

designed for traffic as high as 150 msa. Multi-layer elastic theory adoptedfor stress analysis of the layered elastic system by using semi-mechanisticapproach based on the results of MORT&H research scheme R-56implemented at IIT Kharagpur and software FPAVE developed for theanalysis and design of flexible pavements. Mechanistic Empiricalapproach, which considered the design life of pavement to last till thefatigue cracking in bituminous surface extended to 20 percent of thepavement surface area or rutting in the pavement reached the terminalrutting 20 mm, whichever happened earlier. The same approach and thecriteria are followed in IRC: 37-2012 as well, except that the cracking andrutting have been restricted to 10 percent of the area for design traffic

di 30 illi d d l



strength rigid bases develop wide shrinkage cracks which reflect to thebituminous surface rapidly. Due to lower strength requirement of thecemented sub-bases and bases, the required compressive strength can beeasily achieved even by stabilizing local and marginal materials. Whiletheir strength may be low, it is essential to ensure a reasonable level ofdurability by ‘ Wetting and Drying T est’.

1.5 The following aspects should be given consideratio n while designingto achieve better performing pavement:

(i ) Incorporation of design period of more that fifteen years.

(ii) Computation of effective CBR of sub grade for pavementdesign.

(iii) Use of rut resistant surface layer.

(iv) Use of fatigue resistant bottom bituminous layer.

(v) Selection of surface layer to prevent top down cracking.

(vi) Use of bitumen emulsion/foame d bitumen treated Reclaimedasphalt pavements in base course.

(vii) Consideration of stabilized sub-base and base with locallyavailable soil and aggregates.

(viii) Design of drainage layer.

(ix) Computation of equivalent single axle load considering

(a) Single axle with single wheel(b) Single axle with dual wheels(c) Tandem axles and



1.9 For design traffic less than 2 msa, IRC:SP:72 - 2007 “Guidelines forthe design of flexible pavements for the low volume rural roads” would beapplicable.2. COMPONENT OFFLEXIBLE PAVEMENTS

2.1 Flexible Pavements: - Flexible Pavements are those pavementswhich on the whole have low or negligible flexural strength and arerather flexible in their structural action under the loads. The flexiblepavement layers reflect the deformation of the lower layer on to thesurface of the layer.

2.2 Components of Flexible Pavement

Flexible Pavements include pavements with bituminous surfacing over:

(i) Granular base and sub-base

(ii) Cementitious bases and sub-base s with a crack relief layer ofaggregate interlayer below the bituminous surface.

(iii) Cementitious bases and sub-bases with SAMI in-betweenbituminous surfacing and the cementitious base layer forretarding the reflection cracks into the bituminous layer.

(iv) Reclaimed Asphalt Pavement (RAP) with or without additionof fresh aggregates treated with foamed bitumen/bitumen emulsion.

(v) Use of deep strength long life bituminous pavement is also

included.

2.3 A typical flexible pavement consists of following components: -



3. TRAFFIC DESIGN

3.1 Design Factors: - The various factors to be considered for thedesign of pavements are given as under:



grained soil matrix (the material forming the hill itself becomesroad bed material).

(b) Hilly regions normally receive very high rainfall (reaching ashigh as 3.000 mm and even more than 10,000 mm annually in

certain areas) spread over 6 months or so with very highintensity for short duration. This results in saturated road bedfor prolonged periods and creates problems of drainage ofpavement, erosion and instability.

(c) Large scale differences in day and night temperatures causethermal stresses.

(d) Atmosphere at high altitude gets exposed to higher degree ofsolar radiation and has effect on performance characteristics ofmaterials like bitumen which tends to become harder andbrittle.

(e) Some regions in high altitudes (and even at lower altitudes inNorthern Himalayan ranges) receive snow fall with some areasremaining snow bound in winter. Apart from extreme cold andproblems of snow clearance, issues like frost heave, icing,repeated freezing and thawing create problems of design,composition construction, drainage and maintenance ofpavement.

(f) Road construction period available in high altitude and snowfall areas is very limited and design of pavement and selectionof materials for same need special consideration so that thework is done with speed in the short working season.

3.3. A pavement design may have to meet any of the followingrequirements:-



(iv) Spectrum of axle loads.

(v) Vehicle Damage Factor (VDF)

(vi) Distribution of commercial traffic over the carriageway.

3.4.1.2 Only the number of commercial vehicle having gross vehicleweight of 30 kN or more and their axle-loading is considered for thepurpose of design of pavement.

3.4.1.3 Assessment of the present day average traffic should be basedon seven-day-24-hour count made in accordance with IRC:9- 1972 “ TrafficCensus on Non- Urban Roads”.

3.5 Traffic Growth Rate

3.5.1 The present day traffic has to be projected for the end ofdesign life at growth rates (r) estimated by studying and analyzing thefollowing data:-

(i) The past trends of traffic growth and

(ii) Demand elasticity of traffic with respect to macro -economicparameters (like GDP or SDP) and expected demand due tospecific developments and land use changes likely to takeplace during design life.

3.5.2 If the data for the annual growth rate of commercial vehiclesis not available or if it is less than 5 percent , a growth rate of 5 percentshould be used (IRC:SP:84-2009).



3.7 Vehicle Dam ag e Facto r

3.7.1 The guidelines use Vehicle Damage Factor (VDF) in estimation ofcumulative msa for thickness design of pavements. In case of cementedbases, cumulative damage principle is used for determining fatigue life ofcementitious bases for heavy traffic and for that spectrum of axle loads isrequired.

3.7.2 The Vehicle Damage Factor (VDF) is a multiplier to convert thenumber of commercial vehicles of different axle loads and axleconfiguration into the number of repetitions of standard axle load ofmagnitude 80 kN. It is defined as a equivalent number of standard axles

per commercial vehicle. The VDF varies with the vehicle axleconfiguration and axle loading.

3.7.3 The equations for computing equivalency factors for single, tandemand tridem axles given below should be used for converting different axleload repetitions into equivalent standard axle load repetitions. Since the

VDF va lues in AASHO Roa d Test fo r fl ex ib le and rig id pave me nt are no tmuch different, for heavy duty pavements, the computed VDF values areassumed to be same for bituminous pavements with cemented andgranular bases.

4 Single axle with single wheel on either side = axle load in kN ..3.1

65



can have different pavement thickness for divided highways dependingupon the loading pattern.



Table 3.1 Sample size for Axle Load Survey

Total number of Commercial Vehic les pe r day

Minimum Percentage ofCommercial Traffic to beSurveyed

<3000 20 percent3000 to 6000 15 percent>6000 10 percent

3.7.5 Ax le lo ad spec trum The spectrum of axle load in terms of axle weights of single,

tandem, tridem and multi-axle should be determined and compiled undervarious classes with class intervals of 10 kN, 20 kN and 30 kN for single,tandem and tridem axles respectively.

3.7.6 Where sufficient information on axle loads is not available and thesmall size of the project does not warrant an axle load survey, the defaultvalues of vehicle damage factor as given in Table 3.2 may be used.

Table 3.2 Indicative VDF Values

Initial Traffic Volume inTerms of Commercial

Vehic les pe r Da y

TerrainRolling/Plain Hilly

0-150 1.5 0.5150-1500 3 5 1 5



(iii) Four-lane single carriageway roads : The design should bebased on 40 percent of the total number of commercial vehicles inboth directions.

(iv) Dual carriage way roads : The design of dual two-lanecarriageway roads should be based on 75 percent of the number ofcommercial vehicles in each direction. For dual three-lanecarriageway and dual four – lane carriageway, the distribution factorwill be 60 percent and 45 percent respectively.

3.8.2 Where there is no significant difference between traffic in eachof the two directions, the design traffic for each direction may be assumedas half of the sum of traffic in both directions. Where significantdifference between the two streams exists, pavement thickness in eachdirection can be different and designed accordingly.

3.8.3 For two way two lane roads, pavement thickness should besame for both the lanes even if VDF values are different in differentdirections and designed for higher VDF. For divided carriageways, eachdirection may have different thickness of pavements if the axle load

patterns are significantly different.3.9 Computation of Design Traffic

3.9.1 The design traffic in terms of the cumulative number of standardaxles to be carried during the design life of the road should be computedusing the following equation:

N = 365 X [(1+r) n -1] X A X D X F …..3.5



3.9.2 The traffic in the year of completion is estimated using thefollowing formula:

A = P (1+r ) x Where

P = Number of commercial vehicles as per last count.

x = Number of years between the last count and theyear of completion of construction.

3.10 Road capacity and pavement width

3.10.1 The width of the carriageway will be arrived at based on theobserved traffic census and or design road capacity as per Table-3.3

Table-3.3 Design Road Capacity (Service volume) for Hill Roads

S/No Type of road Width ofRoad

For lowcurvature (0-200 degreesPer KM)*

For highcurvature (above200 degrees PerKM)*

1 Single lane 3.75 m 1,600 1,400

2 Two Lane 7.00 m 7,000 5,000

* It is the summation of total deviation angle of curves per KM.





the alignment will be required for determination of design CBR. The 90thpercentile of these values should be adopted as the design CBR (such that90 per cent of the average CBR values are equal or greater than thedesign value) for high volume roads such as Expressways, NationalHighways and State Highways. For other categories of roads, design canbe based on 80th percentile of laboratory CBR values. Method ofcomputation of 90th percentile CBR is given in Annex-III. Pavementthickness on new roads may be modified at intervals as dictated by thechanges in soil profile but generally it will be found inexpedient to do sofrequently from practical considerations. The maximum permissiblevariation within the CBR values of the three specimens should be asindicated in Table 4.1

Table 4.1 Permissible Variation in CBR Value

CBR (per cent) Maximum Variation in CBR Value

5 (+/-)15-10 (+/-)2

11-30 (+/-)331 and above (+/-)5

Where variation is more that the above, the average CBR should be theaverage of test results from at least six samples and not three.

4.2 Effective CBR

Where there is significant difference between the CBRs of the selectsubgrade and embankment soils, the design should be based on effectiveCBR. The effective CBR of the subgrade can be determined from Fig 4.1.





5 . PRINCIPLE OFDESIGN OF FLEXIBLE PAVEMENT

5.1 Pavement Model

5.1.1 A flexible pave me nt is mo de le d as an el as ti c mu lt il aye r st ructu re .Stresses and strains at critical locations (Fig.5.1) are computed using alinear layered elastic model. The Stress analysis software IITPAVE hasbeen used for the computation of stresses and strains in flexible

pavements. Tensil e strain Є t at the bottom of the bituminous layer andthe vertical subgrade strain Є v on the top of the subgrade areconventionally considered as critical parameters for pavement design tolimit fatigue and rutting in the bituminous layers and non-bituminouslayers respectively. The computation also indicates that tensile strainnear the surface close to the edge of a wheel can be sufficiently large toinitiate longitudinal surface cracking followed by transverse crackingmuch before the flexural cracking of the bottom layer if the mix tensilestrength is not adequate at higher temperatures.

Fig. 5.1



fatigue denotes the fatigue life of the pavement. In these guidelines,cracking in 20 per cent area has been considered for traffic up to 30 msaand 10 per cent for traffic beyond that.

5.2.2 Fatigue model

Two fatigue equations were fitted, one in which the computed strains in80 per cent of the actual data in the scatter plot were higher than thelimiting strains predicted by the model (and termed as 80 per centreliability level in these guidelines) and the other corresponding to 90 percent reliability level. The two equations for the conventional bituminousmixes designed by Marshal method are given below:

N f = 2.21 * 10 -0 4 x [1/ Є t ] 3.89 * [1/MR] 0.854 (80 per cent reliability)

N f = 0.711*10 -0 4 x [1/ Є t] 3.89 *[1/MR] 0.854 (90 per cent reliability)

(Equation 5.1 & 5.2)Where,

N f = Fatigue life in number of standard axles,

Є t= Maximum tensile strain at the bottom of the bituminous layer,and

M R = Resilient modulus of the bituminous layer.

As per the then preva il ing pract ic e, the mixes us ed in the pavement sunder study sections were generally designed for 4.5 per cent air voidsand bitumen content of 4.5 per cent by weight of the mix (which in termsof volume would come to 11.5 per cent). Most literature recommend a



increased by about three times. The recommendation in these guidelinesis to target low air voids and higher bitumen content for the lower layerto obtain fatigue resistant mix.

Equation 5.1 is recommended for use for traffic up to 30 msa wherenormal bituminous mixes with VG 30 bitumen can be used. Equation 6.3is recommended for use or traffic greater than 30 msa where richerbituminous mixes with stiffer VG 40 binder should be used. Volume ofstiffer grade bitumen is possible to be increased by slightly opening thegrading. The guidelines recommend that the designer should considerthese aspects with a view to achieving a high fatigue life of bituminousmixes.

5.3 Rutting in Pavement

5.3.1 Rutting is the permanent deformation in pavement usuallyoccurring longitudinally along the wheel path. The rutting may partly becaused by deformation in the subgrade and other non-bituminous layerswhich would reflect to the overlying layers to take a deformed shape. Thebituminous mixes also may undergo rutting due to secondary compactionand shear deformation under heavy traffic load and higher temperature.Excessive rutting greatly reduces the serviceability of the pavement andtherefore, it has to be limited to a certain reasonable value. In theseguidelines the limiting rutting is recommended as 20 mm in 20 per cent ofthe length for design traffic up to 30 msa and 10 per cent of the length forthe design traffic beyond.

5.3.2 Rutting Model

Like the fatigue model, rutting model also has been calibrated in the R-56st dies sing the pa ement performance data collected d ring the R 6



subgrade. This needs to be addressed. The recommendatio n in theseguidelines is to provide rut resistant bituminous mixes using higherviscosity grade bitumen or modified bitumen.

5.4 Top Down Cracking in Bituminous Layer

While fatigue cracking is conventionally considered as a ‘bottom -upcracking’ phenomenon, ‘top down cracking’ has also been observed on highvolume roads in the country, because of excessive tensile stressesdeveloping at the top surface due to heavy axle loads. These guidelinesrecommend that a high modulus rut as well as fatigue resistant mix toprevent top down cracking.

5.5 Cementitious Sub-base and Base

5.5.1 Cementitious materials normally crack due to shrinkage andtemperature changes even without pavement being loaded. Slow settingcementitious materials having low cement content develop fine cracks andhave to be preferred to high cement content mixes producing wider cracks.While making a judgment on the strength values for design, the reductionin strength due to the cracked condition of these layers need to be fullyrecognized. The Elastic modules (E) recommended for design is muchlower than their respective laboratory value obtained from unconfinedcompression test. The extent of reductions proposed has been generallyin agreement with practices followed in the national standards of othercountries like Australia, South Africa, MEPDG of the USA etc. There arelimited data in the country on the field performance of such type of

construction to understand and model their performance in the field.Therefore, the new pavements constructed with these materials need to beclosely monitored by Falling Weight Deflectometer (FWD) for thee al ation of material properties for f t re g idance These instr ctions



for the entire axle load spectrum. The design requirement is that thecumulative damage of all wheel loads should be less than 1 during thedesign life of a pavement. If it is greater than 1, the section has to bechanged and iteration done again. The first model is taken from the

Australi an expe ri ence, wh ile the se co nd one is sugg est ed in MEPDG. Th esecond level analysis is necessary only when very heavy traffic isoperating on the highways. The two fatigue equations are given below:

A. Fa tigu e Li fe in Terms of Stand ard Axl es

12

N = RF (11300/E 0.804 + 191)

Є t

Where,

RF = Reliability factor for cementitious materials for failure againstfatigue.

= 1 for Expressways, National Highways and other heavyvolume roads

= 2 for others carrying less than 15 trucks per day.

N = Fatigue life of the cementitious material

E = Elastic modulus of cementitious material.

Є t = tensile strain in the cementitious layer, micro strain.

B F i E i f C l i D A l i





6. COMPOSITION OF PAVEMENT

6.1 The sub-base and the base layer can be unbound (e.g. granular) orchemical stabilized with stabilizers such as cement, lime, fly ash andother cementitious stabilizers. In case of pavements with cementitiousbase, a crack relief layer provided between the bituminous layer and thecementitious base delays considerably the reflection crack in thebituminous course. This may consist of crushed aggregates of thickness

100 mm of WMM conforming to IRC/MORTH Specifications or Stress Ab so rb ing Memb ra ne In te rla ye r (SAMI) of el as tomeri c modi fi ed binder atthe rate of about 2 liter/m2 covered with light application of 10 mmaggregates to prevent picking up of the binder by constructiontraffic(AUSTROADS).

The unbound base layer may consist of granular layer such as Wet MixMacadam (MORTH Specification for Road & Bridge Works) and waterbound macadam. The base layer may consist of granular materialstreated with bitumen emulsion of SS2 grade or foamed bitumen. Freshaggregates or aggregates obtained from reclaimed asphalt pavementswhen treated with foamed bitumen or bitumen emulsion should have therequired indirect tensile strength to be considered as a base layer.

The sub-base layer serves three functions, viz., to protect the subgrade

from overstressing, to provide a platform for the construction traffic andto serve as drainage and filter layer . The design of sub-base , whetherbound or unbound, should meet these functional requirements.



distribution of the sub-base material should be strictly enforced in orderto meet strength, filter and drainage requirements of the granular sub-base layer. When coarse graded sub-base is used as a drainage layer, Los

Ange le s ab ra sion va lue shoul d be less than 40 so tha t there is noexcessive crushing during the rolling and the required permeability isretained and fines passing 0.075 mm should be less than 2 per cent.

6.2.1.3 The sub-base should be composed of two layers, the lowerlayer forms the separation/filter layer to prevent intrusion of subgradesoil into the pavement and the upper GSB forms the drainage layer todrain away any water that may enter through surface cracks.

The drainage layer should be tested for permeability and gradation maybe altered to ensure the required permeability. Filter and drainage layerscan be designed as per IRC: SP: 42-1994 (33) and IRC: SP : 50-1999(34).

6.2.1.4 Strength parameter

The relevant design parameter for granular sub-base is resilient modulus(M R ), which is given by the following equation:

M Rgsb = 0.2h0.45 * M R subgrade Eq …6.1

Where h = thickness of sub-base layer in mm

M R value of the sub-base is dependent upon the MR value of the subgrade

since weaker subgrade does not permit higher modulus of the upper layerbecause of deformation under loads.

d b b l



The relevant design parameter for bound sub-bases is the Elastic ModulusE, which can be determined from the unconfined compressive strength ofthe material. In case of cementitious granular sub -base having a 7-day

UCS of 1.5 to 3 MPa, the laboratory based E value (AUSTROADS) is givenby the following equation:

E cgsb = 1000 * UCS Eq …6.2

Where UCS = 28 day strength of the cementitious granular material

Equation 13.9 gives a value in the range of 2000 to 4000 MPa. Since the

sub-base acts as a platform for the heavy construction traffic, lowstrength cemented sub-base is expected to crack during the constructionand a design value of 600 MPa is recommended for the stress analysis.Poisson’s ratio may be taken as 0.25.

If the stabilized soil sub-bases have 7-day UCS value in the range 0.75 to1.5 MPa, the recommended E value for design is 400 MPa with Poisson’sratio of 0.25.

6.3 Base Layer

6.3.1 Unbound base layer

The base layer may consist of wet mix macadam, water bound macadam,crusher run macadam, reclaimed concrete etc, relevant specifications of

IRC/MORTH are to be adopted for the construction. When both sub-baseand the base layers are made up of unbound granular layers, thecomposite resilient modulus of the granular sub-base and the base is



recommend use of Equation 6.2 for the cemented layer. Curing ofcemented bases after construction is very important for achieving therequired strength as described in IRC: SP-89 and curing should startimmediately by spraying bitumen emulsion or periodical mist spray ofwater without flooding or other methods.

6.3.2.2 Strength parameter

Flexural strength is required for carrying out the fatigue analysis as perfatigue equation. MEPDG suggests that the modulus of rupture forchemically stabilized bases can be taken as 20 per cent of the 28 dayunconfined compressive strength. The same is recommended in these

guidelines. The following default values of modulus of rupture arerecommended for cementitious bases (MEPFG).

Cementitious stabilized aggregates - 1.40 MPa

Lime – fly ash-soil - 1.05 MPa

Soil cement - 0.70 MPa

Poisson’s ratio of the cemented layers may be taken as 0.25.

6.3.2.3 Durability criteriaThe minimum cementitious material in the cementitious base layer shouldbe such that in a wetting and drying test (BIS: 4332 (Part IV)-1968, theloss of weight of the stabilized material does not exceed 14 per cent after

12 cycles of wetting and drying. In cold and snow bound regions like Arunac hal Pra de sh , Jammu & Kashmir, Lada kh , Hima cha l Prade sh etc .,durability should be determined by freezing and thawing test and the loss

f h h ld b l h f l ( (



heavier loads because of high confining pressure. If there is shoving anddeformation in the unbound layer caused by the construction traffic, thegranular layer may be treated with 1 to 2 per cent bitumen emulsion ofgrade MS to avoid reshaping.

6.3.2.6 Modulus of crack relief layer

The resilient modulus of a good quality granular layer provided betweenthe cementitious and bituminous layers is dependent upon theconfinement pressure under wheel load. The modulus may vary from 250to 1000 MPa and a typical value of 450 MPa may be used for the

sandwiched aggregate layer for the analysis of pavements, Strong supportfrom the cementitious base, results in higher modulus than what is givenby Equation 6 .3. Poisson’s ratio of t he aggregate relief layer may betaken as 0.35. A brief description on strength and resilient modulus ofcementitious materials is given in Annex VIII.

6.3.3 Bitumen emulsion/foamed bitumen treatedaggregates/reclaimed asphalt base

If the base is made up of fresh aggregates or milled material fromreclaimed asphalt pavements treated with foamed bitumen emulsion, thevalue of resilient modulus of the material may be taken as 600 MPa whilethe laboratory values may range from 600 to 1200 MPa. The abovementioned resilient modulus value can be ensured if the Indirect TensileStrength (ASTM: D7369-09) of the 100 mm diameter Marshall specimen of

the Emulsion/Foamed Bitumen treated material has a minimum value of100 kPa in wet condition and 225 kPa in dry condition under a rate ofloading of 50 mm/minute (59) at 25oC. Poisson’s ratio is recommended as





6.5. For areas with heavy snow precipitation where mechanized snowclearance operations are undertaken as well as at locations, like bus stopsand roundabouts, consideration ought to be given to the provision ofbituminous concrete in single or multiple courses so as to render thesurface more stable and waterproof. Mastic Asphalt may be used at bus-stops and intersections.



7. PAVEMENT DESIGN PROCEDURE

7.1 Using IITPAVE

Any combination of tr aff ic an d pave ment la ye r co mp os it ion ca n be tr iedusing IITPAVE. The designer will have full freedom in the choice ofpavement materials and layer thickness. The traffic volume, number oflayers, the layer thickness of individual layers and the layer propertiesare the user specified inputs in the Program, which gives strains atcritical locations as outputs. The adequacy of design is checked by theProgram by comparing these strains with the allowable strains as

predicted by the fatigue and rutting models. A satis factory pavementdesign is achieved through iterative process by varying layer thickness or,if necessary, by changing the pavement layer materials. IRC: 37-2012may be referred for outline of procedures for using IITPAVE. ( Softwareof IIT Pave is attached with this Instruction)

7.2 Using Design Catalogues

Design catalogue giving pavement compositions for various combinationsof traffic, layer configuration and assumed material properties is given inChapter-9. If the designer chooses to use any of these combinations and issatisfied that the layer properties assumed in the design catalogue can beachieved in the field, the design can be straightway adopted from therelevant design charts given in the catalogue.

7.3 Material Properties

Regardless of the design procedure, it is essential that the materialti d t d l ft d ti g l t t t th



8. PAVEMENT DESIGN CATALOGUES

Five different combinations of traffic and material properties have beenconsidered for which pavement composition has been suggested in theform of design charts presented in Plates 1 to 24. Each combination hasbeen supported with illustration to compare the proposed design thic knessin the design catalogue with that given by IITPAVE (Clauses 8.1 to 8.5).The five combinations are as under:

(i ) Granular Base and Granular Sub base, (Cl 8.1) (Plate 1 to 8)

(ii) Cementitious Base and Cementitious Sub base with aggregateinterlayer for crack relied. Upper 100 mm of the cementitiousbase is the drainage layer. (Cl 8.2) Plate 9 to 12)

(iii) Cementitious base and Sub base with SAMI at the interface ofbase and the bituminous layer. (Cl 8.3) (Plate 13 to 16)

(iv) Foamed bitumen/bitumen emulsion treated RAP or freshaggregates over 250 mm Cementitious Sub base (Cl 8.4) (Plate17 to 20)

(v) Cementitious base and granular Sub base with crack relieflayer of aggregate layer above the cementitious base. (Cl 8.5)(Plate 21 to 24 )

Note:



8.1 Granular Base and Granular Sub-base

Fig. 8.1 Bituminous Surfacing with Granular Base and GranularSub-base

Fig. 8.1 shows the cross section of a bituminous pavement with granular

base and Sub base. It is considered as a three layer elastic structureconsisting of bituminous surfacing, granular base and Sub base and thesubgrade. The granular layers are treated as a single layer. Strain andstresses are required only for three layer elastic system. The criticalstrains locations are shown in the figure. For traffic > 30 msa, VG 40bitumen is recommended for BC as well as DBM for plains in India.Thickness of DBM for 50 msa is lower than that for 30 msa for a few casesdue to stiffer bitumen. Lower DBM is compacted to an air void of 3 percent after rolling with volume of bitumen close to 13 per cent (Bitumencontent may be 0.5 per cent to 0.6 per cent higher than the optimum).Thickness combinations up to 30 msa are the same as those adopted in









For the given composition of Pavement thickness, 90% Reliability isadopted i.e., Eq. 5.3 and Eq. 5.5 are used (Equations 5.1 and 5.4 with 80%reliability are used for design traffic up to 30 msa).

Al lo wa bl e Hori zonta l Te ns il e St ra in in Bi tumi nou s La ye r is 15 3 x 10 -6 for VG 40 mi xes (Allo wable va lue is 17 8 x 10 -6 from Eq. 5.1 for a mix with VG30 used in IRC: 37 -2001).

Al lo wa bl e Ve rt ica l Co mpress ive St rain on Su bgra de is 29 1 x 10 -6(Allowable value is 370 x 10-6 from Eq. 5.4 used in IRC: 37 -2001).

From PLATE 7, BC = 50 mm, DBM = 125 mm, WMM = 250 mm, GSB-200

mm. The computed strains From IITPAVE Software are

Horizontal Tensile Strain in Bituminous Layer is 149 x 10 -6 < 153 x10 -6 Ve rti ca l Co mpre ss ive St ra in on Subgrade is 244 x 10 -6 < 29 1 x 10 -6 .Hencethe Pavement Composition is Safe.

8.2 Bituminous Pavements with Cemented Base and CementedSub base with Crack Relief Interlayer of Aggregate







(MR = 450 MPa), Cemented base = 110 mm (E=5000 MPa), cemented Subbase = 250 mm (600 MPa)

Equations 5.3, 5.5 and 5.6 are used as design criteria.

Al lo wa bl e Horizont al Te ns il e St ra in in Bi tumi no us Layer is 153x10 -6

Al lo wa bl e Ve rti ca l Compressi ve St rai n on Sub grade is 291x 10 -6

Al lo wa bl e Tensi le St ra in in Cementi ti ous Layer is 64.7 7 x 10 -6 . FromIITPAVE Software the computed strains are

Horizontal Tensile Strain in Bituminous Layer is 131 x 10-6

Ve rt ical Co mpre ss ive Strain on Subgrade is 21 3 x 10 -6

Tensile Strain in Cementitious Layer is 52 x 10 -6

Hence the Pavement Composition is Safe. Design should also be checkedfor fatigue damage.

Minimum thickness bituminous layer for major highways is recommendedas 100 mm as per the AASHTO 93 guidelines.

8.3 Cemented Base and Cemented Sub base with SAMI atthe Interface of Cemented Base and the BituminousLayer



Fig. 8.3 Bituminous Surfacing with Cemented Granular Base andCemented Granular Sub-base with Stress Absorbing MembraneInterlayer (SAMI)

Fig. 8.3 shows a four layer pavement consisting of bituminous surfacing,

cemented base cemented Sub base and the subgrade. For traffic > 30 msa, VG 40 bi tume n is used. DBM ha s air vo id of 3 per ce nt aft er ro ll ing(Bitumen content is 0.5 per cent to 0.6 per cent higher than the optimum).Cracking of cemented base is taken as the life of pavement. Minimumthickness of bituminous layer for major highways is recommended as 100mm as per the AASHTO 93 guidelines. Stress on the underside of thebituminous layer over un-cracked cemented layer is compressive. Upper100 mm of the cemented Sub base is porous and functions as drainagelayer over the cemented lower Sub base.





SAMI is provided on the top of cemented base.

For the given composition of Pavement thickness, 90% Reliability isadopted.e., Equations 5.3, 5.5 and 5.6 are used.

Al lo wa bl e Horizont al Te ns il e St ra in in Bi tumi no us Layer is 153 x 10 -6

Al lo wa bl e Ve rti ca l Compressi ve St rai n on Subgrade is 291 x 10 -6

Al lo wa bl e Tensi le St ra in in Ce me nt it io us La ye r is 64.77 x 10 -6

From IITPAVE Software the computed strains are

Horizontal Tensile Strain in Bituminous Layer is-4.2 x 10 -6 (Compressive).

Ve rti ca l Co mpress ive St ra in on Subgr ade is 19 3 x 10 -6

Tensile Strain in Cementitious Layer is 58 x 10 -6

Minimum thickness of 100 mm has been adopted even though there is nottensile stress at the bottom as per AAHSTO 93 guidelines. The PavementComposition is safe. The reduction in thickness of the cemented baseincrease the bending stresses considerably because it is inverselyproportional to the square of the thickness. Design should be checkedagainst fatigue damage.

8.4 Foamed Bitumen/Bitumen Emulsio n Treated RAP/AggregatesOver Cemented Sub-base



Fig. 8.4 shows a four layer pavement consisting of bituminous surfacing,recycled Reclaimed asphalt pavement, cemented sub-base and thesubgrade. VG 40 bitumen is for traffic > 30 msa. Even bitumenemulsion/foamed bitumen treated fresh aggregates can used to obtainstronger base of flexible pavements as per the international practice.DBM air void of 3 per cent after rolling (Bitumen content is 0.5 per centto 0.6 per cent higher the optimum). Fatigue failure of the bituminouslayer is the end of pavement life. Cement sub-base is similar to that inClause 8.3.





(i ) Al lowable Hori zont al Tensi le St ra in in Bi tumi no us Laye r is 153 x 10 -6

(ii) Allowable Vertical Compressive Strain on Subgrade is 291 x 10 -6


Horizontal Tensile Strain in Bituminous Layer is 131 x 10 -6

Ve rti ca l Co mp re ss ive St ra in on Su bgrade is 277 x 10 -6 Minimum thickness of 100 mm has been adopted for traffic greater than30 msa as per AAHSTO 93 Guidelines. Hence the Pavement Compositionis Safe.

8.5 Cemented Base and Granular Sub -base with Crack Relief

Layer of Aggregate Interlayer Above the Cemented Base



bitumen emulsion if the surface of the granular layer is likely to bedisturbed by construction traffic. Emulsio n can be mixed with water tomake the fluid equal to optimum water content and added to the WMMduring the processing. The granular sub-ba se should consist of drainage(grading 4 of Annex V, Table V-1) as well as filter/separation layer.Upper 100 mm of GSB is drainage layer having a permeability of 300meter/day. A reliability of 80 per cent is used for traffic up to 30 msa and90 per cent for traffic > 30 msa. VG 30 bitumen is recommended fortraffic up to 30 msa and VG 40 for traffic > 30 msa. For colder area,recommendatio n of IRC: 111-20 09 shall be followed. The differentcatalogue of thickness is:





MR of Aggregate layer = 450 MPa, E of cemented base = 5000 MPa, E ofgranular sub-base = 75 X (0.2) x (250) 0.45 = 179.955 = 180 MPa

From PLATE 23, Pavement composition BC + DBM = 100 mm, Aggregateinterlayer = 100 mm, cemented base = 190 mm, granular subbase = 250mm

For the given composition of Pavement thickness, 90 per cent Reliabilityis adopted i.e. Equation 5.3, Equation 5.5 and Equation 5.6 are used.

(i)Allowable Horizontal Tensile Strain in Bituminous Layer is 153x10 -6

(ii)Allowable Vertical Compressive Strain on Subgrade is 291 X 10 --6

Al lowable Tensi le St ra in in Ceme nt iti ous Layer is 64.77 x 10 -6


Horizontal Tensile Strain in Bituminous Layer is 127 x 10 -6

Ve rti ca l Compress ive St ra in on Sub grade is 16 5.4 x 10 -6 Tensile Strain in Cementitious Layer is 63.6 x 10 -6

Hence the Pavement Composition is Safe.

9.6 Other Pavement Compositions

There can be large number of combinations for a good pavementdepending upon the availability of materials. A strong subgrade and astrong Sub base which are non-erodible over a period of time due to pore

f d f



Fig. 8.6 Bituminous Surfacing with Wet Mix Macadam Base andCemented Sub-base

Illustration 1

Traffic = 100 msa, Subgrade CBR = 8 per cent, Pavement Composition:Trial Bituminous layer



Tensile strain at the bottom of Bituminous Layer ( Є t) = 139 * 10 -6

Compressive strain on the top of subgrade ( Є z) = 248 * 10 -6

Thickness can be optimized by different trails. Low strength cementedsub-base without a strong cemented base is not suitable for Wet areas.

Illustration 2

Traffic = 5 msa, Subgrade CBR = 8 per cent, Pavement Composition :Bituminous layer (BC + DBM) = 75 mm, WMM base = 100 mm, Cemented

sub-base = 150 mm.

For 8 per cent CBR, Modulus of subgrade = 17.6*80 -6 4 = 66 MPa, E

MR bituminous layer = 1700 MPa, MR WMM = 350 MPa,

E cemente d sub-base = 600 MPa

For 80 per cent reliability,

Al lo wa bl e Te ns il e st ra in on the bo ttom of Bi tu mi nous la ye r ( Є t) = 425.5 *10 -6

Al lo wa bl e Co mpress ive st ra in on the to p of sub grade ( Є z) = 784.3 * 10 -6

For the above thickness, the strains at the critical locations calculated byIITPAVE software are:

l h b f ( ) 6



9. INTERNAL DRAINAGE IN PAVEMENTS

9.1 The performance of a pavement can be seriously affected if adequate

drainage measures to prevent accumulation of moisture in the pavementstructure are not taken. Some of the measures to guard against poordrainage conditions are maintenance of transverse section in good shapeto reasonable cross fall so as to facilitate quick run-off surface water andprovision of appropriate surface and sub-surface drains where necessary.Drainage measures are especially important when the road is in cuttingor built on low permeability soil of situated in heavy rainfall/snow fallarea.

9.2 On new roads, the aim should be to construct the pavement as farabove the water table as economically practicable. The difference betweenthe bottom of sub grade level and the level of water table/high flood level,generally, not be less than 1.0 m or 0.6 m in case of existing road whichhave no history of being overtopped. In water logged areas, where the subgrade is within the zone of capillary saturation, consideration should begiven to the installation of suitable capillary cut-off as per IRC: 34 atappropriate level underneath the pavement.

9.3 When the traditional granular construction is provided on arelatively low permeability sub grade, the granular sub-base should be

extended over the entire formation width in order to drain the pavementstructural section. Care should be exercised to ensure that its exposedends do not get covered by the embankment soil. The trench type section



D 15 of filter layer ≤5 Eq … 9.2D 85 of subgrade

D 50 of filter layer ≤2 5 Eq … 9.3D 50 of subgrade

D85 means the size of sieve that allows85 percent by weight of thematerial to pass through it. Similar is the meaning of D 50 and D 15.

The permeable sub-base when placed on the erodible sub grade soilshould underlain by a layer of filter material to prevent the intrusion ofsoil fitness into the drainage layer (Flag 11.2). Non -woven geo-syntheticalso can be provided to act as a filter/separation layer. Some typicaldrainage system is illustrated in Figs.9.1, 9.2 and 9.3.





coarse graded granular sub-base would have the necessary permeability of300 m /day with percent fines passing 0.075 mm sieve less that 2 percent.Laboratory test should be conducted for the evaluation of the perm eabilityof the drainage layer. If the surface of the open graded drainage layer is

likely to be disturbed by the construction traffic the layer may be treatedwith 2 percent cement/2-2.5 percent of bituminous emulsion without anysignificant loss of permeability. Field test by Ridgeway in USA indicatedthat it is the duration of low intensity sustained rainfall rather that highintensity rainfall that is critical for infiltration of water into thepavement. It was found that the infiltration rate through the cracks was0.223 Cum/day/m and this value can be used for design for drainage layerin the absence of field data. The infiltration rate per unit area q in Cum/Sqm can be expressed as:

Qi = lcNc/Wp + Wc/Cs Wp+ Kp

Where,

lc = Crack infiltratio n rate (0.223 Cum/day/mN c= Number of longitudinal crack (i.e. number of lanes plus

one)W p = Width of pavement subjected to infiltrationW c = Length of the transverse cracks (equal to the width of

the Pavement)C s = Spacing of transverse crack s (taken as 12 m for

bituminous Pavement)



10 DESIGN IN FROST AFFECTED AREAS

10.1 In areas susceptible to frost action, the design will have to be related

to actual depth of penetration and severity of the frost. At the sub gradelevel, fine grained clayey and silty soils are more susceptible to iceformation, but freezing conditions could also develop within the pavementstructure if water has a chance of ingress from above.

10.2 One remedy against frost attack is to increase the depth ofconstruction to correspond to the depth of frost penetration, but this maynot always be economically practicable. As a general rule, it would beinadvisable to provide total thickness less than 450 mm even when theCBR value of the sub grade warrants a smaller thickness. In addition, thematerials used for building up the crust should be frost resistant.

10.3 Another precaution against frost attack is that water should not beallowed to collect at the sub grade level which may happen on account ofinfiltration through the pavement surface or verges or due to capillary

rise from a high water table. Whereas, capillary rise can be prevented bysoil drainage measures and cut-offs, infiltrating water can be checkedonly by providing a suitable wearing surface.

10.4 In areas susceptible to frost action, the design will have to be relatedto actual deptt of penetration and severity of the frost. At the sub- andgrade level, fine grained clayey and silty soils are more susceptible to ice

formation, but freezing conditions could also develop within the pavementstructure if water has a chance of ingress from above.



10.7.1 Based on study of literature and certain trials the specifications forpavement in High Altitude/Snow Bound areas are formulated as under:-

10.7.2 Frost Action (frost heaving and thawing: Frost can be definedas process of freezing or deposit / covering of minute ice crystals formed

from frozen water vapor. Due to the exposure of the area to sub-zerotemperatures for months together, the soil temperature falls below thefreezing point. Due to the fall in temperature, moisture at sub grade levelfreezes and results in formation of ice crystals. When water freezes, itexpands about 9 per cent of its original volume and is known as frostheave. In some cases, water becomes super cold and remains in liquidstate at temperatures well below the freezing point. The super cold water

and ice crystals have strong affinity, with a result the water is drawn atice crystals that are initially formed and thus continue to grow until icelenses begin to form. The ice lenses in turn grow until frost heavingresults. Fig 4 illustrates ice-lens formation and frozen soil strata.

Fig. – 10 .1 Frozen Soi l and Lens



results in higher potential for moisture absorption. After several cycles offreezing and thawing, a large portion of the sub grade supporting capacityis lost.

10.7.4 In high altitude areas, flexible pavements become brittle and least

ductile during the period of subzero temperature, when the greatestshrinkage tendency and heave occur, Brittleness of the pavement resultsin cracking of pavement surface. Cracks at pavement surface providemeans for ingress of moisture into the base/sub-base /sub-grade. Thisoffers a point where raveling starts and where freezing of moisture in andimmediately below the cracks add to further widen and intensify thecracks as a result of which the life of pavement is affected adversely.

10.8 Design

11.8.1 The General principle of design for pavement in High Al ti tude /Snow Bo un d area wou ld be the same as those in th is TI .However, special care/treatment is required in sub grade which aresusceptible to frost. Therefore, before design of pavement in such areassusceptibility of the sub grade to frost should be determined by testingthe sub grade soil. The general characteristics of the frost susceptible soilbased on the US Army Corps of Engineers guidelines are given in Table -6.

Table-10.1 Frost Susceptible Soils

S/No Group Description Remarks

01 F1 Gravelly soils containing between Least frost3 and 20 per cent finer than susceptibility0.02 mm by weight and least thaw

weakening



(d) Varved clays with non-uniformsub grade conditions

10.8.2 In the Table-10.1 the soil is grouped as F1, F2, F3, & F4. The soilgroup F1 and F2 are least / moderately susceptible to frost and as such nospecial treatment need to be given and the provision in this TI may be

followed. In the case of soil falling under group F-3 and F-4 which arehighly frost susceptible, a layer of 300 mm non frost susceptible (NFS)material to be provided on the sub grade before the pavement as pernormal design is provided.

10.8.3 The criteria for selection of NFS material will be as follows.

10.8.3.1 Graded gravel : Not more than 8% passing 75 micron sieve,plasticity index not more than 6 and liquid limit not more than 25.

10.8.3.2 Poorly graded sands: Generally 100% passing 4.75 mm sieve,with max 10 % passing 75 micron sieve and max 5% passing 50 micronsieve.

10.8.3.3 Fine uniform sand: Generally 100% passing 425 micron sievewith max 18% passing 75 micron sieve and max 8% passing 50 micronsieve.

10.8.3.4 It may, however, be noted that the criteria of NFS material givenabove are the limiting conditions and at site, material of better quality(i.e. having less than 8% passing 75 micron sieve with PI less than 6 andLL less than 25) may be available in the form of natural gravel/granularmaterial, which may be used for layer of NFS material, instead ofsearching for the materials only as per the limiting criteria given above.It may be also noted that the provision of layers of NFS material is

required only in highly frost susceptible area and not throughout thelength of the road, where sub grade is already non frost susceptible orleast/moderately frost susceptible.



NFS sub grade are given in Fig-5 to 8 in case of frost- susceptible sub-grade additional 300 mm thick layer of NFS material to be provided.

10.9.3 Pavement design for protection against frost action

11.9.3.1 For the areas which are affected by frost action two deferentconcepts are available for design of pavements. These concepts are,control of surface deformation by provision of sufficient pavementthickness to reduce frost penetration and design for reduced sub gradestrength during the frost-melt period. Both methods of design areexplained below:-

(a) Limited sub grade frost penetrationIn this method, sufficient thickness of non-frost susceptible materialis used that only limited, tolerable penetration of freezingtemperature into the frost-susceptible sub grade occurs. By thismeans, both pavement heave and sub grade weakening are reducedsufficiently in amount as well as frequency of occurrence andduration so that their effects may be neglected. Depth of frostpenetration can be worked out from the conditions developed by

Aldri ch as pe r the modi fi ed Be rggre n’ s fo rmula give n as under: -

Z = 48 KF A _ __ _ __ _ __ _

L

Z = Depth of frost penetration in m

K = Thermal conductivity (which depends upon dry density ofl d l h 0



reduced sub grade strength and thickness of pavement required. Butthese cannot be readily extended to our condition.

10.9.3.2 Both systems of assessing frost affected sub grade given in para

10.9.3 above may be taken as for information. If necessary, study of sitesby expert agencies in the field and site investigation will have to be done.

10.10 Construction

10.10.1 The general method of construction would be the same as pernormal pavement work. However, following specific care/precautions to betaken before /during construction of pavement in high altitude /snow

bound areas.10.10.2 Investigation of sub grade soil at least up to a depth of 60 cmmust be done to find whether it is frost-susceptible or not and pavementcomposition decided as given 10.8.1 and 10.8.2.

10.10.3 The surface of pavement should be flexible enough to toleratesmall heaves.

11.10.4 It should be impervious and have adequate surface drainage.

11.10.5 It should have adequate thickness and stability.

10.10.6 The binder used should have enough ductility and should notbecome brittle in very cold weather.

10.10.7 The aggregates to be used should be evaluated for dry and wetstrength as well as water absorption. In case they loose strength incontact with water, suitable treatment should be given before use oralternatively some other suitable aggregates be used Similarly due



Fig –10.2 For non-frost susceptible soil

Note:- 1. For Frost Susceptible Subgrade 300 mm thick Layer of NFSmaterial will be provided in addition.

2. All Dimensions are in mm & sketch is not to scale

INTER LOCKING CONCRETE BLOCK





11 DESIGN OF PAVEMENT FOR EXPANSIVE SOILS

11.1 Potentially expansive soils, such as, black cotton soils aremontmorillonite clays and are characterized by their extreme hardness

and deep cracks when dry and with tendency for swelling during theprocess of wetting. Roadbeds made up of such soils when subjected tochanges in moisture content due to seasonal wetting and drying or due toany other reason undergo volumetric changes leading to pavementdistortion, cracking and general unevenness. In semi-arid climaticconditions, pronounced short wet and long dry conditions occur, whichaggravate the problem of swelling and shrinkage. Due recognition of theseproblems at the design stage itself is required so that counter measurescould be devised and incorporated in the pavement structure. A properdesign incorporating the following measures may considerably minimizethe problems associated with expansive soils.

11.2 Subgrade Moisture, Density and Design CBR

12.2.1 The amount of volume change that occurs when an expansive soilroad bed is exposed to additional moisture depends on the following:-

(a) Dry density of the compacted soil(b) Moisture content(c) Structure of soil and method of compaction

11.2.2 Expansive soils swell very little when compacted at low densities

and high moisture but swell greatly when compacted at high densities andlow moisture. Hence where the probability of moisture variation in thesub grade is high , it is expedient to compact the soil slightly wet of thef ld d d h b f f ld l



11.4 Buffer Layer

12.4.1 There is a definite gain in placing the pavement on a non-expansive cohesive soil cushion of 0.6 – 1.0 m thickness. It prevents

ingress of water in the underlying expansive soil layer, counteractsswelling and secondly even if the underlying expansive soil heaves, themovement will be more uniform and consequently more tolerable.However, where provision of non-expansive buffer layer is noteconomically feasible, a blanket course of suitable material and thicknessas discussed inpara 12.5 below must be provided.

11.5 Blanket Course

12.5.1 A blanket course of at least 225 mm thickness and composed ofcoarse/medium sand or non-plastic moorum having PI less than fiveshould be provided on the expansive soil sub grade as a sub -base to serveas an effective intrusion barrier. The blanket course should extend overthe entire formation width.

11.5.2 Alternatively, lime-stabilized black cotton sub-base extending overthe entire formation width may be provided together with measures forefficient drainage of the pavement section.



12 . LIFE CYCLE AND SPECIFICATIONS FORFLEXIBLEPAVEMENT RESURFACING ON BRO ROADS

12.1 Based on study of the life and specifications of Flexible pavementresurfacing for roads in BRO, the periodicity of bituminous resurfacing

and specifications of resurfacing has been approved by MORT&H videletter F.63 (20)/BRDB / Project/90/80435/DGBR/DS dated 01 may1991.The periodicity of bituminous resurfacing are given in Table-8 andspecifications of bituminous renewal coat are given in Table-9.

Table 12.1. Life Cycle and Specifications for Flexible PavementResurfacing

S/ Road/Traffic/ Type of resurfacing with periodicityNo. Intensity in years

SCSD 20 mm PC 40 mmBC

01 Road in Mizoram __ 3 years extendableto 4 years with addi-tion of bitumen byweight of aggregate

02 Other roads in areas 4 6 __ upto 300 cm annualrainfall

03 Other roads in areas

with annual rainfallmore than 300 cm andareas subject to snow

bl f l d f f l b l



Table 12.2 Life Cycle and Specifications for Flexib le PavementResurfacing

Traffic Intensity Specification of bituminous resurfacing withIn msa respect to annual rainfall conditions

Low upto Medium High Remarks150 cms 150-300 cms More than

300 cms

2.0-3.0 20 mm PC 20 mm PC or 20 mm PC orMSS MSS

3.0-50. 20 mm PC 20 mm PC or 25 mm PC oror MSS MSS MSS

5.0-7.0 25 mm PC BC (40 mm) BC (40 mm)or MSS

7.0-10.0 BC (40 mm) BC (40 mm) BC (40 mm)

Ab ove 10 BC (40 mm) BC (40 mm) (B C 40 mm)

(b) The periodicity of renewal vide table 8 above may be taken as aguide and any requirements of renewal before expiry of thestipulated period, may be carried out after examination by aTechnical Board.

(c) The renewal of surface may be carried out in continuous stretchesand small intermediary stretches even though not completed theti l t d i d b f d i lt l t bt i

( ) h h d h b h d



(iv) Stretches strengthened more than 5 years ago but have not receivedrenewal treatment and showing signs of distress due to growingtraffic

(v) Length of stretch should generally be not less than 10 kms, unless

such stretches are in continuation of stretches included in earlierIRQP/strengthened reach.

12.5 Specifications

(a) For existing pavement thickness less than 200 mm 3 x 75mm WBM/WMM+20 mm PC & Seal Coat or MSS

(b) For existing pavement thickness between 200 mm and 250mm2 x 75 mm WBM / WMM + 20 mm Premix Carpet & Seal Coat orMSS

(c) For existing pavement thickness between 250 mm and 300mm 75 mm BUSG +20 mm PC and Seal Coat or MSS

(d) For existing pavement thickness of 300 mm or more (i) 50 mm BM+25 mm SDBC if undulations / cracks in theexisting surface are less than 10% of the surface area

(ii) 75 mm BM+25 mm SDBC if undulation cracks in the existingsurface are between 10-20%

12.6 Binder in case of SDBC/BC as surfacing shall be polymer/rubbe rmodified bitumen as per IRC SP- 53 2002 “Guidelines on use of polymerand rubber modified bitumen in road construction”.

12 7 The above treatments proposed in para 4 1 2 (a) (b) & (c) for exist ing

(iii) A f ibl h h f i di l h ld b



(iii) As far as possible, the stretches for periodic renewal should befor a continuous length of about 10 KMs, or aggregated toabout 10 KMs for the purpose of estimate and tender and incontinuation of reaches improved under IRQP or renewedearlier.

12.9.2 Specifications for renewal

(a) 20 mm MSS/20 mm PC with seal coat for low traffic roads(<1500 CVD)

(b) 25 mm BC for high traffic road (>1500 CVD). BC shall be laidonly where the exiting surface has BC as wearing course.

(c) Binder in case of SDBC/BC as surfacing shall bepolymer/rubber modified bitumen as per IRC : SP-53 2002“Guidelines on use of polymer and rubber modified bitumen inroad construction”

(d) Extra quantity for patching /rectification ofpotholes/undulation may be provided where required as persite conditions as assessed by technical board and approved by

CE Project.

CONCLUSION

1. This technical instruction lays down the procedure for design of flexiblepavement on BRO roads. As said earlier this TI has to be read inconjunction with MORT&H and IRC standards and specifications as wellas IS codes (Bureau of Indian Standards) as required.

2 for design of pa ements nder special circ mstances detailed

ANNE X I



ANNE X- I

Wo rked-out Ex amp les Ill us tr at in g the Des ign Me tho d

(i) Bituminous Pavements with Untreated Granular Layer

Example-I: Design the pavement for construction of a new flexiblepavement with the following:

Data

(i ) Four lane divided carriageway(ii) Initial traffic in the ear completion of construction =5000 CV/day

(Sum of both directions)(iii) Percentage of Single, Tandem and Tridem axles are 45 per cent, 45

per cent and 10 per cent respectively(iv) Traffic growth rate per annum =6.0 per cent(v ) Design life = 20 years(vi) Vehi cl e dama ge facto r = 5.2

(Based on axle load survey)(vii) CBR of soil below the 500 mm of the subgrade = 3 per cent(viii) CBR of the 500mm pf the subgrade = 10 per cent

from borrow pits

Design Calculations

(i) Lane Distribution factor = 0.75(ii) Initial traffic = 2500 CVPD assuming 50 percent in each direction.

dditi l bit OBC) WMM d GSB 185 t



additional bitumen over OBC) over WMM and GSB = 185 mm atreliability of 90 per cent.

(The thickness of the bituminous layer as per IRC : 37-2001 = 210 mm atreliability of 80 per cent).

(ii) Bituminous Pavement with Cemented Base and CementedSub-base with Aggregate Interlayer of 100 mm

Design traffic as above 131 msa.

Bituminous layer with VG 40 (BC + DBM) = 100 mm.

Aggrega te interl aye r = 100 mm.

Cemented base = 120 mm (thickness of the cemented base

for CBR 5 and 10 are 130 mm and 100 mm

respectively).

Cemented sub-base layer for drainage and separation = 250 mm.

The upper 100 mm of the cemented sub-base should be open graded sothat its permeability is about 300 mm/day or higher for quick removal ofwater entering from the surface.Checking of the safety of cemented base due to spectrum of axle

loads resulting in msa of 131

Since there are plenty of single, tandem and tridem axle loads which arefar higher than standard axle load used for pavement design, thickness ofcement layer must be checked for sudden fracture of the brittle materiallike cemented base due to higher axle loads using cumulative damageprinciple. One tandem axle is taken as two single axles and one tridem

145 155 2 58 310 330 2 08 465 495 1 80



145-155 2.58 310-330 2.08 465-495 1.80

135-145 5.8 290-310 4.17 435-465 4.4

125-135 5.8 270-290 4.17 405-435 4.4

115-125 11.82 250-270 12.67 375-405 13.10105-115 11.82 230-250 12.67 345-375 13.10

95-105 12.9 210-230 10.45 315-345 10.90

85-95 12.16 190-210 10.45 285-315 10.4

<85 32.3 170-190 7.05 255-285 7.15

<170 28.28 <255 28.33Total 100 Total 100 Total 100

Cumulative fatigue damage analysis is computed as follows for Single,Tandem and Tridem Axle respectively considering flexural strength ofcemented base as 1.4 MPa.

Cumulative fatigue damage analysis for Single AxleModulus of Rupture of the cementitious base = 1.4 MPa

Ax le Loa din kN

ExpectedRepetitions

Stress inMPa

StressRatio

Fatigue Life FatiguelifeConsumed

190 72504 0.70 0.50 5.37E + 5 0.14

180 90631 0.66 0.47 1.12E + 06 0.08

170 90631 0 63 0 45 2 33E + 06 0 04

Axl e Expected Stress in Stress Fatigue Fatigue



Axl eLoad inkN

ExpectedRepetitions

Stress inMPa

StressRatio

FatigueLife

FatiguelifeConsumed

400 419166 0.74 0.53 2.58E +

05

1.626

380 459950 0.70 0.50 5.37E +

05

0.857

360 459950 0.66 0.47 1.12E +

06

0.411

340 471279 0.63 0.45 2.33E +06

0.202

320 471279 0.59 0.42 4.85E +

06

0.097

300 944823 0.55 0.39 1.01E +

07

0.094

280 944823 0.52 0.37 2.10E +

07

0.045

260 2870721 0.48 0.34 4.38E +

07

0.066

240 2870721 0.44 0.32 9.11E +07

0.032



Checks must be done for cumulative fatigue damage as explained in the



Checks must be done for cumulative fatigue damage as explained in theprevious example.

The upper 100 mm of the cemented sub-base should be open graded sothat its permeability is about 300 mm/day or higher for quick removal of

water entering from the surface in high rainfall area.(iv) Bituminous Pavement with Base of Fresh Aggregates or

Reclaimed Asphalt Pavement (RAP) Treated with FoamedBitumen/Bitumen Emulsion and Cemented Sub-Base

Design traffic = 131 msa

Bituminous layer with VG 40 (BC + DBM) = 100 mm.

Treated aggregates RAP = 180 mm estimated from plates 18 and 19 anddesign is found to be safe from strain consideration.

Cemented sub-base layer for drainage and separation = 250 mm.

(v) Bituminous Pavement with Cemented Base and Granular Sub-base with 100 mm WMM Layer Over Cemented Base

Design traffic = 131 msa

BC (VG 40) = 50 mm, DBM (VG 40) = 50 mm, WMM = 100 mm, cementedbase = 195 mm estimated from plates 22 and 23 for fatigue damageanalysis, GSB = 250 mm.

The upper 100 mm of the cemented/granular sub-base should be opengraded so that its permeability is about 300mm/day or higher for quick

removal of water entering from the surface.Design of Flexible Pavement for 300 msa of Traffic



Bituminous layer must be bottom rich, that is, the bottom layer shouldhave an air-void of 3 per cent after the compaction by traffic. This isachieved by having additional bitumen of 0.5 to 0.6 per cent higher thanthe optimum bitumen content. This can be established from the laboratorytests and a field trail. The bitumen should be grade VG 40 for the plainsin India to control rutting, where temperatures are much higher. In caseof non-availability of VG 40 bitumen, PMB/CRMB has to be used to obtainrut resistant mixes.

Thickness of the Pavement is worked out as:

Thickness of the bituminous layer = 225 mm.

Thickness of Granular Sub-base = 350 mm.Strains in different layers for a design traffic of 300 msa. Al lo wa bl e tens ile st ra in in th e bo ttom bituminous laye r = 1 31 µ∑ (Computed maximum tensile strain = 125 µ Є ).

Al lo wa bl e ve rt ica l subgrade st ra in = 250 µ Є . (Computed maximumvertical subgrade strain = 239 µ Є ).



ANNEXURE –II

PAVEMENT LAYERS WITH CHEMICAL STABILIZED MATERIALS

1. Chemically stabilized soils and aggregates may include all kinds ofstabilization such as cement, lime, lime -flyash, or their combination,proprietary chemical stabilizers, enzymes, polymers and any otherstabilizer provided these meet the strength and durability requirement s ,while cement, lime, lime-fly ash stabilized materials are well known for

their strength , performance and durability, the commercially producedstabilizers should meet the additional requirements of leach ability andconcentration of heavy metals. Where stabilized materials are used in thepavement, only mechanized method of construction for laying andcompaction should be used. The equipment should be capable ofadministering the design doses of stabilizer and quantity of water andproducing a uniform and homogeneous mix. Such materials are also

termed as cemented or cementitious materials.

2. IRC: SP: 89-2010 Guidelines for soil and granular materialstabilization using cement, lime & fly ash has very comprehensivelydescribed the entire process of stabilization. High strength chemicallystabilized layer having a 7-day unconfined strength of 6-12 MPa given

Table 8 of IRC: SP: 89-2010 is not recommended because of wideshrinkage and thermal cracks that may occur during the service.Cementitious materials having lower strength can be used in bases and

09 Standard Test Methods for Unconfined Compressive Strength of



09 Standard Test Methods for Unconfined Compressive Strength ofCompacted Soil-Lime-Mixtures). Accelerated curing may be use to providea correlation between normal and accelerated curing strengths for thematerial-binder combination. Three day curing of lime of lime-fly-ash soilat 50 Degree Cilices is found to be equivalent to about 33 to 38 days ofmoist curing at ambient temperature of about 30 Degree Cilices (16).Some typical values of unconfined compressive strength and modulus ofrupture of lime-fly ash concrete suitable for cemented bases extractedfrom IRC: SP: 20-2001 Rural Road Manual are given below:Extracted from IRC: SP: 20-2002 Rural Road manual

The proportions may vary depending upon the quality of materialsand laboratory tests are required to be done prior to construction toensure that the materials have the minimum strength. Different trials arenecessary to arrive at a good mix proportion for a base and a sub-base.Construction procedure is explained in IRC: SP: 20-2002. Table X1indicates that even for lime-fly ash stabilized materials, flexural strengthcan be about 20 percent of the UCS. Published literature also (16) showsthat flexural strength may be as high as 35 to 40 percent of the UCS oflime or lime-fly ash stabilized soil. The recommendation of MEPDG (3)taking the flexural strength as 20 percent of the UCS is very reasonable iflaboratory date is not available. Long term strength gain for slow settingstabilizers can be considered in design

Table Annex II-1 Expected Strength of Lime-Fly ash ConcreteMixes

E (Cemented base) = kxU CS ... 1



E (Cemented base) kxU CS ... 1UCS = Unconfined strength at 28 days, MPa; k = 1000 to 1250

E value of the cemented bases containing 4 to 6 percent OrdinaryPortland and slag or Pozzolanic cement is recommended as 5000 MPa. Iffield evaluation by PWD indicates higher modulus, fresh estimate ofpavement life can be made.

Poisson’s ratio of the cemented layer may vary from 0.2 to 0.25. Avalue of 0.25 may be adopted. Stresses are not very sensitive to Poisson’sratio

Cemented granular sub base may have cement from 2 to4 percent toget a7 day strength of 1.5 to 3.0 MPa. Its modulus as determined inlaboratory may range from 2000 MPa to 3000 MPa. Since it forms theplatform for the construction traffic, it cracks and cannot retain theinitial modulus. A value of 600 MPa is recommended and its fatiguebehavior is not considered because of cracks. If the stabilized soil subbases have 7 day UCS values in the range 0.75 to 1.5 MPa, therecommended E value for design is 400 MPa. Field tests by PWD shouldbe routinely done to collect data for obtaining pavement designparameters. Cement requirement for a given strength is much higher forsoils than for granular materials. For the commercial ly availablepropriety cementing materials, the binder contents have to be determined

from laboratory tests to meet the strength requirement.

5 C t d b h ld b t d i i l l t

wheels of a construction machinery. Geotextile seal and many other



wheels of a construction machinery. Geotextile seal and many othercommercially available commercially have the promise. SAMI is not veryeffective n if the crack opening is more than 3 mm to retard crackpropagation in the bitum8inous layer.

8. Another method of arresting the cracks from propagating to theupper bituminous layer is to provide an interlayer of good qualityaggregates between the bituminous layer and the cemented base. Theaggregate layer should extend the cemented base by about 0.5 m so thatmoisture, if any, travels down to the porous sub-base. Wet Mix Macadam(WMM) meeting the IRC/MORTH specification can form a good aggregate

interlayer. Being sandwiched between two stiff layers, the aggregatebehaves as layer of high modulus under heavy load while its modulus islower when lighter loads act. Priming and tack coating are requiredbefore laying of the bituminous layer. Use of 1 to 2 percent bitumenemulsion in WMM is needed only when the construction traffic is likely todeform the compacted WMM requiring regarding. It does not improve thecrack resistance of the aggregate layer. Thickness of 75 mm to 150 mmhas been used for the inter layer by different organizations. TheGuidelines propose a thickness of 100 mm.

9. Behaviour of cemented base after traffic associated cracking .thecemented layers may get numerous cracks due to fatigue cracking and itsmodulus may be reduced drastically from 5000 MPa to 500 MPa. Falling

weight deflect meter can be a good tool to examine the condition of thecemented base at any time during its service life. The bituminous layerh littl t il t i b f ki f th t d b b t th l



11. Procedure for the mix design method for cemen titious granularbases and sub-bases can be same as adopted for Dry Lean Concrete(MORTH) except that the cementitious stabilizer content is much lowerdue to low strength requirement. Optimum moisture content has to bedetermined by trial. Since maximum size of aggregates can be 53 mm ,150 mm cubes have to be made at different moisture content andcompacted by vibratory hammer with square plates. Details are given inMORTH Specifications for determination of optimum moisture content,method of curing and evaluation of strength. The properties ofcementitious bases and sub-bases are given in Table Annex II-2.

12. For stabilized soils, even 50 mm diameter, 100 high samples can beused for UCS after curing. Beam size can be 50 mm x50 mm x 300 mm forflexure tests after curing. Field condition may be simulated during thecuring.

13. If the soil is modified by addition f small percentage of lime/cement/other stabilizers, CBR tests can be done to evaluate the quality of themodified soil. If the cement content is 2 percent or higher, unconfinedcompressive strength should be determined to determine the strength ofthe stabilized soil.



ANNEX -I II

(Refer Clause 5.1.1.2)

Preparation of Laboratory Test Specimens for CBR Test and Selection ofSubgrade CBR for Pavement Design

Sample Preparation

(1) Wherever possible, the test specimens should be prepared bystatic compaction but if not possible, dynamic method may beused as an alternative .

Static Compaction

(2) The weight of wet soil at the required moisture content to give theintended density when occupying the standard test mould is calculated as

follows:

Vo lume of mou ld = 2209 cc

Weight of dry soil = 2209 d gm

Weight of the Wet Soil = (100 + m) x 2209 d gm 100

Where,

d = Required dry density in gm/cc



Dynamic Compaction

(4) The soil is mixed with water to give the required moisturecontent, and then compacted into the mould in three layersusing a standard soil rammer. After compa ction, the soil istrimmed flush with the top of the mould with the help of ametal straight edge. The mould is weighted full and empty toenable determination of wet bulk density, and from it,knowing the moisture content, the dry density is calculated.

(5) Further specimens, at the same moisture content, are thenprepared to different dry densities by varying the number ofblows applied to each layer of soil so that the amount ofcompaction that will fill the mould uniformly with calculatedweight of wet soil (vide para 2 above) is known.

Selection of Subgrade CBR for Pavement Design

The CBR values of the subgrade soil varies along a highway alignmenteven on a homogeneous section. 90th percentile CBR isrecommended in the guidelines. Method of dete rmination ofthe 90th percentile is given below. The following exampleillustrates the procedure for finding the design.

16 CBR values for a highway alignment are as follows:

3.5, 5.2, 8.0, 6.8, 8.8, 4.2, 6.4, 4.6, 9.0, 5.7, 8.4, 8.2, 7.3, 8.6,8.9, 7.6



Fig. III.1 Evaluation of Subgrade CBR for Pavement Design

The 90th percentile CBR value = 4.7, and 80th percentile CBR = 5.7 in. As phal t In st it ute of USA (6 ) re commen ds 87.5 perc ent il e subgrademodulus for design traffic greater than one msa.

NOTE : if the data is very large, the CBR values can be grouped for

homogenous section and the same procedure followed.





REFERENCES

(1) AASHTO T307-99 (2003), Standard Method of Test for Determiningthe Resilient Modulus of Soils and Aggregate Materials.

(2) AASHTO (1993) Guide for Design of Pavement Structures, American Asso ci ati on of Sta te High way and Tra nsport ati on Offi ci als ,Washington DC.

(3) AASHTO 20 02 (2 004 ), ‘Gu ide fo r Mechanis tic -Empirical Design ofNew and Rehabilitat ed Pavement’ MEPDG, NCHRP, TRB, FinalReport.

(4) Amaranatha Reddy, M., Sudhakar Reddy, K. and Pandey B.B.(2001),‘Design CBR of Subgrade for Flexible Pavements’, IRC HighwayResearch Bulletin No. 64, June 2001 pp. 61-69.

(5) Asphalt Institute (2003), Performance Graded Asphalt Binder -Specification and Testing, Superpave Series No. 1(SP-1).

(6) Asp halt Institute “Cold Mix Recycling”.

(7) Asphalt In st itu te “As phalt Cold Mix Ma nual” MS 14



(12) ASTM D7369- 09 “Standard Test Method for Determining theResilient Modulus of Bituminous Mixtures by Indirect TensionTest”.

(13) ASTM D7460- 10) “Standard Test Method for Determining FatigueFailure of Compacted Asphalt Concrete Subjected to RepeatedFlexural Bending”.

(14) AUST ROADS (2 004), “Pa veme nt De si gn -A Guide to StructuralDesign of Road Pavements”, Sydney.

(15) Bhattacharya, P.G. and Pandey, B.B. (‘Flexural Fatigue strength ofLime-Laterite Soil Mix tures’) Transportation Research Record 1986,No. 1089, pp. 86-91.

(16) Bhattacharya, P.G. and Pandey, B.B. “Study of Strength and curingof Lime-Stabilised Laterite Soil-Plain and Fibre- Reinforced’ IndianRoads Congress, HRB Bulletin No. 24, 1986, pp 1-26 ’.

(17) BIS: 4332 (Part IV) – (1968, Reaffirmed in 2010), ‘Methods of Testfor Stabilized Soils: Wetting and Drying, Freezing and ThawingTests for Compacted Soil-Cement Mixtures.

(18) Brown, S.F., Brunton, J.M., and Pell, P.S., “The Development andImplementation of Analytical Pavement Design for British

Conditions, proc. of 5th Int. Conf. on struct., Des of Asph.Pavements, Vol. I, 1982, pp. 81-87.



(23) Flaherty, C.A.O, “HIGHWAYS”, 4th Edition, 2004, Butterworh -Heinemann.

(24) Harvey, J.T., Monismith, C.L., Bejarano, M., Tsai, B.W., andKannekanti, V., ‘Long Life AC Pavements: A Discussion of Designand Construction Criteria based on California Experience’International Conference on Design of Long Lasting AsphaltPavements, Aubun, Alabama, USA, pp 284-333.

(25)

http://www.irc.org.in/ENU/knowledge/research/Pages/MORTHResearchReport .aspx

(26) http://www.tpub.com/content/engineering/14070/css/14070_428.htm

(27) http://www.ohio.edu/icpp/upload/Fatique per cent20Characteristics percent20of per cent20RBB-Carpenter.pdf

(28) Haung, Y.H. ( 2004), ‘Pavement Analysis and Design’ 2nd Ed.Pearson/education.

(29) IRC:111- 2009 “Specifications for Dense Graded Bituminous Mixes”.

(30) IRC:SP:89-2010 Guidelines for Soi l and Granular Mate rialStabilisation Using Cement, Lime & Fly Ash.

(31) IRC:81-199 7 “Guidelines for Strengthening of Flexible PavementsUsing Benkelman Beam Deflection Technique”.

http://www.irc.org.in/ENU/knowledge/research/Pages/MORTHResearchReport



http://www.tpub.com/content/engineering/14070/css/14070_428.htm


http://www.ohio.edu/icpp/upload/Fatique








(37) Jack Van Kirk and Glynn Holleran (2000), ‘Reduced Thickness Asphalt Rubber Concr et e’, Is t. Int. Conf. wor ld of Pavement s,Sydney, Australia.

(38) Krishna, M. (2010), ‘Investigations on Long Life BituminousPavements’ M. Tech. thesis, IIT Kharagpur’.

(39) Kumar, S.S., Sridhar, R., Reddy, K.S. and Bose, S. (2008),‘Analytical Investigation on the Influence of Loading andTemperature on Top- Down Cracking in Bituminous Layers’, J.

Indian Roads Congress, Vol. 69-1, pp. 71-77.

(40) Lister, N.W. and Powell, W.D. (1987), Design Practice of BituminousPavements in United Kingdom, Proc. of 6th Int. Conf. on Struct. Desof Asphalt Pavements, Vol1.

(41) Metcalf J.B., Li, Y., Romanoschi, S.A. and Rasoulian, M. (1999),“The Performance and Failure Mo des of Louisiana AsphaltPavements with Soil Cement Bases under Full Scale AcceleratedLoading”, Transportation research record 1673, pp. 9 -15.

(42) Monismith, C.L., Harvey, J.T., Bressette, T., Suszko, C. and Martin,J.S., ‘The I -710 freeway Rehabilitation Project: Mix and StructuralSection Design, Construction Considerations, and Lessons Learned’,International Conference on Design of Long Lasting Asphalt

Pavements, Aubun, Alabama, USA, pp. 217-262.

(43) Lister, N.W. and Powell, W.D. ‘Design Practice for Bituminous



(47) Pavan Kumar. G, (2009), “Effect of Binders on Fatigue Life ofBituminous Mixes”, M. Tech Thesis, IIT Kharagpur.

(48) Philips, S.D. 1994, ‘Theoretical Analysis of Labour -IntensiveConstruction of Water Bound Macadam Roads’. Ph.D. Dissertation,University of the Witwatersrand, Johansnesburg.

(49) Rao, S.K., Das, J.K. and Roychowdhury, P. (2007), Asphalt MixDesign – Refusal Density Approach for Heavily Trafficked Roads,Journal of Indian Congress, Vol. 68, No. 1, pp. 53-64.

(50) Rajsekhar, R. (2011), ‘ Mechanistic Design of Bituminous Pavementswith Different Types of Bases’ M. Tech. Thesis, IIT Kharagpur.

(51) Reddy, K.S. (2007), Investigation of Rutting Failure in SomeSections of National Highway-2 between KM. 317 and KM. 65,Transportation Engineering Section, Department of CivilEngineering, IIT Kharagpur, India.

(52) Reddy, N.M. and Pandey, B.B. (2010), ‘Bituminous Pavement withCementitious Base’ Highway Research Journal, Indian RoadCongress, Vol.3, No. 2, pp. 23-29.

(53) Reddy, K.S. (2005), ‘Top Down Cracking of Bituminous Concrete onGodhra-Shamlajee section of SH-5 in Gujarat.

(54) Research Scheme R- 56 “Analytical Design of Flexible Pavements”Final Report submitted to the Ministry of Surface Transport (Roads





(69) Witczak, M.W. and Mirza, M.A. (1999), ‘Comparison and Assessmentof Fatigue of Elvaloy Modified Asphalt Mixture with Conventional

Asphalt Mixt ures’ A Te ch nical Re po rt prepa re d for Du pont,Delaware, University of Maryland, USA. Witczak161.

(70) IRC:9-1 972 “Traffic Census on Non -Urban Roads”.

(71) IRC:SP:84- 2009 “Manual for Specifications & Standards for FourLaning of Highways Through Public Private Partnership”.





Table Annex II.2 Properties of Cementitious Base and Sub-base

S/No Description UCS (MPa) Modulus of Rupture ElasticModulus, E(MPa) andPoisson Ratio

Range of Modulus Remarks

1. Granularmaterial forbase layer

4.5-7.0 at 7 days forcement (28 days forlime-flyash),determined bytest on 150 mm cube(IRC:SP:89;2010) Cubeshall be made as perIS-516- except thatthey shall becompacted by thevibratory hammer atOMC as per MORTHspecifications for DLC

Determined by thirdpoint bending test at28 days, as per IS-516except that thesample should becompacted by thevibratory hammer withrectangular foot,OMC, (20 percent ofthe UCS at 28 daysmay be taken asdefault value forModulus of Rupture)

E=1000* UCS(MPa) at 28days(Austroads)

Ad op ted va lu eE=5000

= 0.25

Initial Modulus canbe in the range3000-14000MPa(65), Austroadsrecommendsflexural modulus of5000 MPa forpavement designassuming 28 daysUCS of 5 MPa

Material mustpass durabilitytest asprescribed inIRC:SP:89-2010for long termdurability. Lossof weight in 12cycles ofwetting-dryingor freeze thawnot more than12 percent.

2. Granularmaterial forsub-base

1.5-3.0 at 7 days forcement (28 days forlime-flyash),determined by test on150 mm cube(IRC:SP:89:2010)

- E = 600,= 0.25

Inaitial moduluscana be in therange 2000-10000MPa, it may bereduced to 500-800MPa due tocracking by theconstruction traffic(49)

-

3. Granular

material forsub-base(Design traffic, 10 msa)

0.75-1.5 at 7 days for

cement (28 days forlime-fly ash) ,determined by test on150 mm cube(IRC:SP:89:2010)

- E= 400,

= 0.25s

Initial modulus can

be in the range500-7000 MPa, itmay abe reduced to400-600 MPa due tocracking by theconstruction traffic(65)

-



4. Chemicallystabilized soilfor sub-base

UCS:0.75 to 1.5 MPaat 7 days for cement(28 days for limeflyash) UCS is to bedone cylindricalspecimen 50 mm dia

100 mm height (ASTMD-51-2-09)

- E= 400 MPqa The range of themoduli depends onthe soil type

Quantity ofchemicalstabilizerrequirement ismuch largethan that of the

granularmaterial for thesame strength,same strength,Generally notrecommendedfor heavytraffic in wetarea.

5. Chemicallystabilized soilfor base

UCS: 4.5 to 7 MPa at7 days for cement (28days for lime flyash)UCS is to be done oncylindrical specimen50 mm dia 100 mmheight

MR = 0.7 MPa(MEPDG) for UCSvalue of 5.2 MPa forsoil cement.

AS TM -D 16 35 -0 6Standard Test Methodfor Flexural strengthof Soil-Cement UsingSimple Beam withThird-Point Loading

E= 3500 MPa isrecommend byMEPDG for soilcement basevalue is to bedeterminedfrkom theflexkural testby measuringload anddeflection after28 days ofcuring







(v) PCC 14:8 - 150 mm - -

(vi) PCC 1:2:4 - - - 200

(vii) Stone Set Pavement - 150 mm - -

(viii) Sand Layer - - 30 m -

(ix) Precast Cement ConcreteBlock (M-30)

- - 200 mm -

Total 565 mm 750 mm 680 mm 650 mm

(b ) In non-frost susceptiblesoil subgrade

(i) Crushed stone base (CSB) 150 mm 150 mm 150 mm 31

(ii) BM/DBM 75 mm - - -

(iii) Bituminous concrete (BC) 40 mm - - -

(iv) PCC 14:8 - 150 mm - -

(v) PCC 1:2:4 - - - 200

(vi) Stone Set Pavement - 150 mm - -

(vii) Sand Layer - - 30 mm -

(viii) Precast Cement ConcreteBlock (M-30)

- - 200 mm -

Total 265 mm 450 mm 380 mm 350 mm



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