Share It

Share It

Blog Archive

Wednesday, 15 June 2016



1.     Overview of the Highway Planning and Development Process:

Highway design is only one element in the overall highway development process. Historically, detailed design occurs in the middle of the process, linking the preceding phases of planning and project development with the subsequent phases of right of way acquisition, construction, and maintenance. While these are distinct activities, there is considerable overlap in terms of coordination among the various disciplines that work together, including designers, throughout the process.
Although the names may vary by State, the five basic stages in the highway development process are: planning, project development (preliminary design), final design, right-of-way, and construction. After construction is completed, ongoing operation and maintenance activities continue throughout the life of the facility.

1.               Introduction

1.1             Project Background

1.2             Core Network

1.3             Geography

1.4             Climatic Condition

1.5             The Sub-Project Road

2.               Alignment

2.1             General

2.2             Sailent Features

3.               Land Requirement

3.1             General

3.2             Proposed ROW

3.3             Additional Land

4.               Geometric Design Standards

4.1             General

4.2             Terrain

4.3             Design Speed

4.4             Right of Way (ROW)

4.5             Roadway Width

4.6             Carriageway Width

4.7             Earthen Shoulders

4.8             Roadway width at cross-drainage structures

4.9             Sight Distance

4.10          Radius of Horizontal Curve

4.11          Camber & Super elevation

4.12          Vertical Alignment

4.13          Vertical Curves

4.14          Cross Section Element and Side slope

4.15          Extra Widening of Pavement

5.               Topographic Survey

5.1             General

5.2             Traversing

5.3             Levelling

5.4             Cross Section & Detailing

5.5             Data Processing

6.               Soil and Materials Survey

6.1             General

6.2             Soil sample collection and Testing

6.3             Analysis of Test Results

6.4             Coarse and Fine Aggregates

7.               Traffic Survey

7.1             General

7.2             Traffic Data and Analysis

7.3             Traffic Growth Rate and forecast

8.               Pavement Design


8.1             General

8.2             Pavement Design Approach

8.2.1          Design Life

8.2.2          Design Traffic

8.2.3          Determination of ESAL applications

8.2.4          Subgrade CBR

8.3             Pavement composition

9.               Hydrological Survey


9.1             General

9.2             Rainfall Data

9.3             Catchment Area

9.4             Time of Concentration

9.5             Existing Cross Drainage Structures

9.6             Justification for retaining/widening and replacement of culverts

9.7             Hydraulic calculation for Culvert

10.            Design of Cross Drainage


10.1          General

10.2          Hydrological Design

10.3          Design Feature

11.            Protective Works & Drainage


11.1          General

11.2          Road side drain

11.3          Protective Works

12.     Specification

13.     Environmental Issues

14.            Analysis of Rates

15.     Cost Estimate

16.     Construction Programme

17.     Environmental Code of Practice (ECoP)

18.     Road Safety

19.     Road Furniture including Citizen Information Signboards

Various Study Required:

20.            Geometric Design Standards

20.1          General

The geometric design standards for this project conform to MORTH / PMGSY (ADB) guidelines and the guidelines as stated in IRC-SP 20:2002. Recommended design standards vis-à-vis the standards followed for this road are described below.

21.            Topographic Survey

21.1          General

Topographic survey true to ground realties have been done using precision instruments like Total Stations and Auto Levels, and bringing out data in digital form (x, y, z format) for developing digital terrain model (DTM).
The topographic survey was carried out by the Surveyors / Supervisors under the guidance of DRE.
The in-house standards, work procedures and quality plan prepared with reference to IRC: SP 19-2001, IRC: SP 20, IRC: SP 13 (in respect of surveys for rivers / streams) and current international practices have been followed during the above survey.

21.2          Traversing

Traverse will be done by Total Station having angular measurement accuracy of ± 1 sec.
Control pillars were established at suitable intervals along the project corridor and their coordinates were established by Total Station. The starting coordinate was assumed and accordingly the coordinates of the other Reference/ Temporary Benchmark (TBM) were established. All the Control points have been established on concrete pillars.

21.3          Levelling

All leveling for establishing Benchmark are to be carried out as per method adopted by Survey of India. All leveling are to be carried out with Auto Level having accuracy ± 2.5 mm/ km. The Consultant started the work by assuming arbitrary level, as no GTS benchmark was available in the nearby location of the road.

21.4          Cross Section & Detailing

Cross section taken at 50 m interval and at closer interval in curved portion of the existing road. The following features of the road were recorded:
v  Existing road details
v  Existing toe point of Road
v  Canal / River & Banks
v  Natural Surface Points
v  Edge of Water Body / Pond
v  Edge of ditch / Borrow pit
v  Electricity and Telephone poles
v  Edge of Building & Fence line
v  Religious Structure & Graves
v  Temporary House or Hut
v  Edge of Wall
v  Bore Well
v  Concrete Wall
v  Level Crossing / Railway Tracks
v  Trees
v  Cross roads and other major crossings

21.5          Data Processing

All data from topographic survey recorded by total station were downloaded and final alignment, plan, profile is prepared and presented in AutoCAD Format.

22.            Soil and Materials Survey

22.1          General

The soil and material investigations have been done following the guidelines of IRC: SP 20 - 2002 and IRC: SP 72 - 2007 and other relevant IS codes. The potential sources of borrow areas for soil and quarry sites have been identified.

22.2          Soil sample collection and Testing

Soil samples have been collected along and around the road alignment at three (3) locations per km, from the adjoining borrow areas, as well as one sample is collected from the existing road. Soil Classification tests like grain size analysis and Atterberg’s limit were conducted for all the samples collected. Standard Proctor test and the corresponding 4 day soaked CBR test were conducted either for a minimum of one test per km for soil samples of same group or more tests due to variation of soil type. The following tests were conducted as detailed below:
v  Grain size analysis as per IS : 272 (Part 4) – 1985
v  Atterberg’s limit as per IS : 2720 (Part 5) – 1985
v  Standard Proctor density test as per IS : 2720 (Part 7) – 1980
v  4 day soaked CBR test as per IS : 2720 (Part 16) – 1985

22.3          Analysis of Test Results

The laboratory soaked CBR value ranges from 4.2% to 4.4%.

22.4          Coarse and Fine Aggregates

Information regarding the source of aggregate and sand was gathered. The stone aggregate shall be procured from Nalhati. The source and the lead distance from the quarry to project site was finalized in discussion with the PIU. The aggregates and sand shall be used for bituminous work, Concrete works, other pavement works.

23.            Traffic Survey

23.1          General

In the present scenario of new connectivity road, 3 day, 24 hr. traffic volume count has been conducted. The Classified Volume count survey has been carried out in accordance with the requirements of the TOR and relevant codes (IRC: SP: 19-2001, IRC: SP: 20, IRC: SP: 72-2007).The surveys have been carried out by trained enumerators manually under the monitoring of Engineering Supervisor.

23.2          Traffic Data and Analysis

All field data sheet collected from site has been dispatched from site to project design office for data entering and analysis. The traffic count done has been classified into different vehicle category as given below:
v  Motorized vehicle comprising of light commercial vehicle, medium commercial vehicle, heavy commercial vehicle, Car, Jeep, two wheelers etc.
v  Non-motorized vehicles comprising of cycle, rickshaw, cycle van, Animal drawn vehicle etc.
The numbers of laden and un-laden commercial vehicles have also been recorded during the traffic counts. Traffic volume count for this project road has been done during lean season. However, as per local information, the traffic will be double during the peak harvesting season.
Average daily traffic (ADT) has been found for each vehicle type. Computation of Average Annual Daily traffic (AADT) is given below:
T = Average number of vehicles plying during lean season
nT= Enhanced traffic during peak season, over and above lean season traffic T
t = Duration of Harvesting season

23.3          Traffic Growth Rate and forecast

In the absence of any specific information to the designer, an average annual growth rate of 6% over the design life has been adopted. .

24.            Pavement Design

24.1          General

Considering the subgrade strength , projected traffic and the design life, the pavement design for low volume PMGSY roads have been carried out as per guidelines of IRC : SP : 72 – 2007.

24.2          Pavement Design Approach

24.2.1       Design Life

A design life of 10 years is considered for the purpose of pavement design of flexible and granular pavements.

24.2.2       Design Traffic

The average annual daily traffic (AADT) computed in the opening year is 2038 as described in Chapter 7. The total commercial vehicle per day (CVPD) works out to 23.

24.2.3       Determination of ESAL applications

Only commercial vehicles with a gross laden weight of 3 tonnes or more are considered. The design traffic is considered in terms of cumulative number of standard axles to be carried during the design life of the road. The numbers of commercial vehicles of different axle loads are converted to number of standard axle repetitions by a multiplier called the Vehicle Damage Factor (VDF).An indicative VDF value has been considered as the traffic volume of rural road does not warrant axle load survey.
For calculating the VDF, the following categories of vehicles have been considered as suggested in paragraph 3.4.4 of IRC: SP: 72 – 2007.
v  Laden Heavy/Medium Commercial vehicles
v  Un-laden /partially loaded heavy/medium commercial vehicles
v  Over loaded heavy/medium commercial vehicles
Indicative VDF values considered 10% of laden MCV and 10% laden HCV as overloaded & given below:
Vehicle type
Un-laden /Partially laden
Lane distribution factor (L) for Single lane road = 1.0
Cumulative ESAL application = To x 4811 x L, where To = ESAL application per day
The Cumulative ESAL application for the project road works out to 74,907 and falls in traffic category T3 as per paragraph 3.5 of IRC: SP: 72 – 2007.

24.2.4       Subgrade CBR

The average subgrade CBR 4.2, range of 3-4 has been considered.

24.3          Pavement composition

The designed pavement thickness and composition have calculated by referring Figure 4 (Pavement design catalog) of IRC : SP : 72 – 2007.The pavement layers provided are given below:
Top Layer
Premix Carpet with Type B Seal Coat
26 mm
Base Layer
WBM Grading III & WBM Grading II
150 mm
Sub – Base Layer
Granular Sub-base Grading II
175 mm
Total thickness
325 mm

25.            Hydrological Survey

25.1          General

Hydrological survey is necessary for design of adequate and safe Cross Drainage Structures so that the rain water can pass as per natural slope. Hydrological survey of the proposed road is based on the following observations:
v  Rainfall Data
v  Catchments Area
v  Time of Concentration
v  Existing Cross Drainage Structures

25.2          Rainfall Data

Rainfall Data as applicable for the project road has been collected having an average annual rainfall of more than 1500 mm with maximum rainfall occurring in the months of July and August.

25.3          Catchment Area

The Catchments area has been calculated by gathering local information as it could not be calculated from topographical sheets due to their unavailability.

25.4          Time of Concentration

Time of concentration (tc) is calculated from the formula of (0.87 x L3/H)0.385, where L is distance from the critical point to the structure site in km and H is the difference in elevation between the critical point and the structure site in meters.


Sl no
Description of DATA


Site Plan / Internet

Climatic Condition



Survey Data

Geometric Design Standards

Codal Provision

Design Speed

Right of Way (ROW)

Roadway Width

Carriageway Width

As per Client’s requirement / MORTH

Earthen Shoulders

Roadway width at cross-drainage structures

Sight Distance

Radius of Horizontal Curve

Camber & Super elevation

Vertical Alignment

Vertical Curve

MORTH or other standerd

Cross Section Element and Side slope

v  Existing road details
v  Existing toe point of Road
v  Canal / River & Banks
v  Natural Surface Points
v  Edge of Water Body / Pond
v  Edge of ditch / Borrow pit
v  Electricity and Telephone poles
v  Edge of Building & Fence line
v  Religious Structure & Graves
v  Temporary House or Hut
v  Edge of Wall
v  Bore Well
v  Concrete Wall
v  Level Crossing / Railway Tracks
v  Trees
Cross roads and other major crossin
Survey data

Soil and Materials

v  Grain size analysis as per IS : 272 (Part 4) – 1985
v  Atterberg’s limit as per IS : 2720 (Part 5) – 1985
v  Standard Proctor density test as per IS : 2720 (Part 7) – 1980
4 day soaked CBR test as per IS : 2720 (Part 1
Lab Testing

Coarse and Fine Aggregates

Lab Testing

Traffic Data and Analysis

Traffic Survey

Design Traffic


Traffic Survey

Rainfall Data



2.     Difference between Flexible and Rigid Pavement

Flexible pavement
Rigid  pavements
Deformation in the sub grade is transferred to upper layers
Deformation in the sub grade is transferred to subsequence
Have low flexural strength
Have high flexural Strength
Load transferred to gain to gain contract
No such phenomenon of grain to grain load transferred
Have low completion test but high repairing cost
Have low repairing cost but high completion cost
Damaged by oil and chemicals
No damage by oil or Greece
Design Based on load distribution factor
Design based on Flexural strength or slab action

Construction Steps for Cement Concrete Pavement / Road

Concrete pavements are rigid pavements having very high flexure strength as compared to flexible pavements. Concrete pavements can be constructed using two different methods:
1.           Alternate Bay method

2.           Continuous bay method

·                     In alternate bay method, concrete pavement slab are laid on whole width of pavement in alternate bays.
·                     In continuous bay method, concrete pavement slabs are laid continuously only on one bay and another bay is open for the traffic. 
Generally the second method of continuous bay, is preferred over alternate bay method because, traffic movement is allowed while it is restricted in the first. Also, the alternate empty spaces invites the rainwater collection and create in-convenience to the construction work.
Various steps for the construction of concrete pavements:

1.           Preparation of Sub-grade and Sub-base
2.           Placing of forms
3.           Batching of material and Mixing
4.           Transporting and Placing of Concrete
5.           Compaction and Finishing
6.           Floating and Straight Edging
7.           Belting, Booming and Edging
8.                   Curing of Cement concrete

3.     List of some common test:
Sl No
Type Of Test
Requirement as per Code
Code reference
A.     Coarse Aggregate
Sieve Analysis

IS:383 / IS 2386-Part I
Specific Gravity

IS:383 / IS 2386-Part III
Flakiness Index
Maximum 30%
IS:383 / IS 2386-Part I
Crushing Strength
Road -  30% (Max) Other -45% (Max)
IS:383 / IS 2386-Part IV
Impact Value
Road -  30% (Max) Other -45% (Max)
IS:383 / IS 2386-Part IV
Moisture Content
1% - 2%

Abrasion Value
Road -  30% (Max) Other -50% (Max)
IS:383 / IS 2386-Part IV
Maximum 12% & 18%
IS:383 / IS 2386-Part V
Water absorption
1% - 2%
IS:383 / IS 2386-Part III
Alkali Aggregate Reactivity test

IS:383 / IS 2386-Part VII
Deleterious Material Content
Maximum 5%
IS:383 / IS 2386-Part II
Alkali Silica Reactivity Potential of Aggregate

ASTM C 289

Sl No
Type Of Test
Requirement as per Code
Code reference
B.  Soil

Liquid Limit & Plasticity Index
below 50% & 25%
IS: 2720 - PART 5
Maximum Dry Density

IS: 2720 - PART 8
Field Dry Density

IS: 2720 - PART 28 & 29
Swelling Index
Below 50%
IS: 2720 - PART 40
Moisture Content

IS: 2720 - PART 2
C.  Bitumen


ASTM D5 [ASTM, 2001] / 1201 - 1220 :1978

ASTM D1310 / 1201 - 1220 :1978

ASTM D 2042 / 1201 - 1220 :1978

ASTM D113 / 1201 - 1220 :1978

ASTM D2171/ 1201 - 1220 :1978
D.  Cement 

Compressive Strength

IS: 8112 - 2013
Normal Consistency

IS: 8112 - 2013
Setting time

IS: 8112 - 2013

IS: 8112 - 2013

IS: 8112 - 2013



(i) To determine the impact value of the road aggregates;
(ii) To assess their suitability in road construction on the basis of impact value
The apparatus as per IS: 2386 (Part IV) – 1963 consists of:
(i) A testing machine weighing 45 to 60 kg and having a metal base with a painted lower surface of not less than 30 cm in diameter. It is supported on level and plane concrete floor of minimum 45 cm thickness. The machine should also have provisions for fixing its base.
(ii) A cylindrical steel cup of internal diameter 102 mm, depth 50 mm and minimum thickness 6.3 mm.
(iii) A metal hammer or tup weighing 13.5 to 14.0 kg the lower end being cylindrical in shape, 50 mm long, 100.0 mm in diameter, with a 2 mm chamfer at the lower edge and case hardened. The hammer should slide freely between vertical guides and be concentric with the cup. Free fall of hammer should be within 380±5 mm.
(iv) A cylindrical metal measure having internal diameter 75 mm and depth 50 mm for measuring aggregates.
(v) Tamping rod 10 mm in diameter and 230 mm long, rounded at one end.
(vi) A balance of capacity not less than 500g, readable and accurate upto 0.1 g.
The property of a material to resist impact is known as toughness. Due to movement of vehicles on the road the aggregates are subjected to impact resulting in their breaking down into smaller pieces. The aggregates should therefore have sufficient toughness to resist their disintegration due to impact. This characteristic is measured by impact value test. The aggregate impact value is a measure of resistance to sudden impact or shock, which may differ from its resistance to gradually applied compressive load.
The test sample consists of aggregates sized 10.0 mm 12.5 mm. Aggregates may be dried by heating at 100-110° C for a period of 4 hours and cooled.
(i) Sieve the material through 12.5 mm and 10.0mm IS sieves. The aggregates passing through 12.5mm sieve and retained on 10.0mm sieve comprises the test material.
(ii) Pour the aggregates to fill about just 1/3 rd depth of measuring cylinder.
(iii) Compact the material by giving 25 gentle blows with the rounded end of the tamping rod.
(iv) Add two more layers in similar manner, so that cylinder is full.
(v) Strike off the surplus aggregates.
(vi) Determine the net weight of the aggregates to the nearest gram(W).
(vii) Bring the impact machine to rest without wedging or packing up on the level plate, block or floor, so that it is rigid and the hammer guide columns are vertical.
(viii) Fix the cup firmly in position on the base of machine and place whole of the test sample in it and compact by giving 25 gentle strokes with tamping rod.
(ix) Raise the hammer until its lower face is 380 mm above the surface of aggregate sample in the cup and allow it to fall freely on the aggregate sample. Give 15 such blows at an interval of not less than one second between successive falls.
(x) Remove the crushed aggregate from the cup and sieve it through 2.36 mm IS sieves until no further significant amount passes in one minute. Weigh the fraction passing the sieve to an accuracy of 1 gm. Also, weigh the fraction retained in the sieve.
Compute the aggregate impact value. The mean of two observations, rounded to nearest whole number is reported as the Aggregate Impact Value.
Sample 1
Sample 2
Total weight of dry sample ( W1 gm)
Weight of portion passing 2.36 mm sieve (W2 gm)
Aggregate Impact Value (percent) = W2 / W1 X 100
Mean =

Aggregate Impact Value =
Classification of aggregates using Aggregate Impact Value is as given below:
Aggregate Impact Value
Exceptionally Strong
10 – 20%
Satisfactory for road surfacing
Weak for road surfacing

27.            Determine the Maximum Dry Density and the Optimum Moisture Content of Soil

This test is done to determine the maximum dry density and the optimum moisture content of soil using heavy compaction as per IS: 2720 (Part 8) – 1983.The apparatus used is
i) Cylindrical metal mould – it should be either of 100mm dia. and 1000cc volume or 150mm dia. and 2250cc volume and should conform to IS: 10074 – 1982.
ii) Balances – one of 10kg capacity, sensitive to 1g and the other of 200g capacity, sensitive to 0.01g

iii) Oven – thermostatically controlled with an interior of non corroding material to maintain temperature between 105 and 110oC
iv) Steel straightedge – 30cm long
v) IS Sieves of sizes – 4.75mm, 19mm and 37.5mm

A representative portion of air-dried soil material, large enough to provide about 6kg of material passing through a 19mm IS Sieve (for soils not susceptible to crushing during compaction) or about 15kg of material passing through a 19mm IS Sieve (for soils susceptible to crushing during compaction), should be taken. This portion should be sieved through a 19mm IS Sieve and the coarse fraction rejected after its proportion of the total sample has been recorded. Aggregations of particles should be broken down so that if the sample was sieved through a 4.75mm IS Sieve, only separated individual particles would be retained.

Procedure To Determine The Maximum Dry Density And The Optimum Moisture Content Of Soil

A) Soil not susceptible to crushing during compaction –

i) A 5kg sample of air-dried soil passing through the 19mm IS Sieve should be taken. The sample should be mixed thoroughly with a suitable amount of water depending on the soil type (for sandy and gravelly soil – 3 to 5% and for cohesive soil – 12 to 16% below the plastic limit). The soil sample should be stored in a sealed container for a minimum period of 16hrs.

ii) The mould of 1000cc capacity with base plate attached, should be weighed to the nearest 1g (W1 ). The mould should be placed on a solid base, such as a concrete floor or plinth and the moist soil should be compacted into the mould, with the extension attached, in five layers of approximately equal mass, each layer being given 25 blows from the 4.9kg rammer dropped from a height of 450mm above the soil. The blows should be distributed uniformly over the surface of each layer. The amount of soil used should be sufficient to fill the mould, leaving not more than about 6mm to be struck off when the extension is removed. The extension should be removed and the compacted soil should be levelled off carefully to the top of the mould by means of the straight edge. The mould and soil should then be weighed to the nearest gram (W2).

iii) The compacted soil specimen should be removed from the mould and placed onto the mixing tray. The water content (w) of a representative sample of the specimen should be determined.
iv) The remaining soil specimen should be broken up, rubbed through 19mm IS Sieve and then mixed with the remaining original sample. Suitable increments of water should be added successively and mixed into the sample, and the above operations i.e. ii) to iv) should be repeated for each increment of water added. The total number of determinations made should be at least five and the moisture contents should be such that the optimum moisture content at which the maximum dry density occurs,
lies within that range.

B) Soil susceptible to crushing during compaction –
Five or more 2.5kg samples of air-dried soil passing through the 19mm IS Sieve, should be taken. The samples should each be mixed thoroughly with different amounts of water and stored in a sealed container as mentioned in Part A)

C) Compaction in large size mould –
For compacting soil containing coarse material upto 37.5mm size, the 2250cc mould should be used. A sample weighing about 30kg and passing through the 37.5mm IS Sieve is used for the test. Soil is compacted in five layers, each layer being given 55 blows of the 4.9kg rammer. The rest of the procedure is same as above.


Bulk density Y(gamma) in g/cc of each compacted specimen should be
calculated from the equation,

Y(gamma) = (W2-W1)/ V
where, V = volume in cc of the mould.
The dry density Yd in g/cc

Yd = 100Y/(100+w)
The dry densities, Yd obtained in a series of determinations should be plotted against the corresponding moisture contents,w. A smooth curve should be drawn through the resulting points and the position of the maximum on the curve should be determined. The dry density in g/cc corresponding to the maximum point on the moisture content/dry density curve should be reported as the maximum dry density to the nearest 0.01. The percentage moisture content corresponding to the maximum dry density on the moisture content/dry density curve should be reported as the optimum moisture content and quoted to the nearest 0.2 for values below 5 percent, to the nearest 0.5 for values from 5 to 10 percent and to the nearest whole number for values exceeding 10 percent

Penetration Test on Bitumen
The penetration test is one of the oldest and most commonly used tests on asphalt cements or residues from distillation of asphalt cutbacks or emulsions. The standardized procedure for this test can be found in ASTM D5 [ASTM, 2001]. It is an empirical test that measures the consistency (hardness) of an asphalt at a specified test condition.
Procedure of Penetration Test on Bitumen:
In the standard test condition, a standard needle of a total load of 100 g is applied to the surface of an asphalt or Liquid bitumen sample at a temperature of 25 °C for 5 seconds. The amount of penetration of the needle at the end of 5 seconds is measured in units of 0.1 mm (or penetration unit). A softer asphalt will have a higher penetration, while a harder asphalt will have a lower penetration. Other test conditions that have been used include
  1. 0 °C, 200 g, 60 sec., and
  2. 46 °C, 50 g, 5 sec.
The penetration test can be used to designate grades of asphalt cement, and to measure changes in hardness due to age hardening or changes in temperature.

Flash Point Test on asphalt:
The flash point test determines the temperature to which an asphalt can be safely heated in the presence of an open flame. The test is performed by heating an asphalt sample in an open cup at a specified rate and determining the temperature at which a small flame passing over the surface of the cup will cause the vapors from the asphalt sample temporarily to ignite or flash. The commonly used flash point test methods include
  1. The Cleveland Open Cup (ASTM D92)
  2. Tag Open Cup (ASTM D1310).
The Cleveland Open-Cup method is used on asphalt cements or asphalts with relatively higher flash points, while the Tag Open-Cup method is used on cutback asphalts or asphalts with flash points of less than 79 °C. Minimum flash point requirements are included in the specifications for asphalt cements for safety reasons. Flash point tests can also be used to detect contaminating materials such as gasoline or kerosine in an asphalt cement. Contamination of an asphalt cement by such materials can be indicated by a substantial drop in flash point.
When the flash point test is used to detect contaminating materials, the Pensky-Martens Closed Tester method (ASTM D93), which tends to give more indicative results, is normally used. In recent years, the flash point test results have been related to the hardening potential of asphalt. An asphalt with a high flash point is more likely to have a lower hardening potential in the field.

Initial and Final Setting Time Of Cement
 To do so we need Vicat apparatus conforming to IS: 5513 – 1976, Balance, whose permissible variation at a load of 1000g should be +1.0g, Gauging trowel conforming to IS: 10086 – 1982.
Procedure to determine initial and final setting time of cement

i) Prepare a cement paste by gauging the cement with 0.85 times the water required to give a paste of standard consistency.
ii) Start a stop-watch, the moment water is added to the cement.
iii) Fill the Vicat mould completely with the cement paste gauged as above, the mould resting on a non-porous plate and smooth off the surface of the paste making it level with the top of the mould. The cement block thus prepared in the mould is the test block.


Place the test block under the rod bearing the needle. Lower the needle gently in order to make contact with the surface of the cement paste and release quickly, allowing it to penetrate the test block. Repeat the procedure till the needle fails to pierce the test block to a point 5.0 ± 0.5mm measured from the bottom of the mould.The time period elapsing between the time, water is added to the cement and the time, the needle fails to pierce the test block by 5.0 ± 0.5mm measured from the bottom of the mould, is the initial setting time.


Replace the above needle by the one with an annular attachment. The cement should be considered as finally set when, upon applying the needle gently to the surface of the test block, the needle makes an impression therein, while the attachment fails to do so. The period elapsing between the time, water is added to the cement and the time, the needle makes an impression on the surface of the test block, while the attachment fails to do so, is the final setting time.

Traffic is the most important factor influencing pavement performance. The performance of pavements is mostly influenced by the loading magnitude, configuration and the number of load repetitions by heavy vehicles. The damage caused per pass to a pavement by an axle is defined relative to the damage per pass of a standard axle load, which is defined as a 80 kN single axle load (E80). Thus a pavement is designed to withstand a certain number of standard axle load repetitions (E80’s) that will result in a certain terminal condition of deterioration.

Moisture can significantly weaken the support strength of natural gravel materials, especially the subgrade. Moisture can enter the pavement structure through cracks and holes in the surface, laterally through the subgrade, and from the underlying water table through capillary action. The result of moisture ingress is the lubrication of particles, loss of particle interlock and subsequent particle displacement resulting in pavement failure.
The subgrade is the underlying soil that supports the applied wheel loads. If the subgrade is too weak to support the wheel loads, the pavement will flex excessively which ultimately causes the pavement to fail. If natural variations in the composition of the subgrade are not adequately addressed by the pavement design, significant differences in pavement performance will be experienced.

Failure to obtain proper compaction, improper moisture conditions during construction, quality of materials, and accurate layer thickness (after compaction) all directly affect the performance of a pavement. These conditions stress the need for skilled staff, and the importance of good inspection and quality control procedures during construction. Ø MAINTENANCE:
 Pavement performance depends on what, when, and how maintenance is performed. No matter how well the pavement is built, it will deteriorate over time based upon the mentioned factors. The timing of maintenance is very important, if a pavement is permitted to deteriorate to a very poor condition, as illustrated by point B in Error! Reference source not found., then the added life compared with point A, is typically about 2 to 3 years. This added life would present about 10 percent of the total life. The cost however of repairing the road at point B is minimum four times the cost if the road had been repaired at point A. The postponement of maintenance hold further implications, in that for the cost of repairing one badly deteriorated road (Point B), four roads at point A would have to be deferred, which would mean that in a few years the rehabilitation cost could be 16 times as much. Thus, postponing maintenance because of budget constraints, will result in a significant financial penalty within a few years.

Maintaining and Repairing Bituminous Road:
The maintenance and repair of roads and airfields are particularly important because of increased mobility in modern warfare. Damage caused by the weight of heavy loads, the abrasive action of military traffic, and combat conditions must be repaired as quickly as possible. The repairs are often made under adverse conditions, such as shortages of manpower, material, equipment, and time and the possibility of an attack. Continuous maintenance cannot be overemphasized; small repairs made immediately are much cheaper than major repairs made at a later date.
 For effective results, the cause of a failure must be corrected. If surface repairs are made without correcting a defective subgrade or base, the damage will reappear and repairs can be more extensive. Also, a minor maintenance job that is postponed can develop into a major repair job involving the subgrade, the base, and the wearing surface. Repairing the surface without correcting the base is justifiable only as a temporary measure to meet immediate needs under combat or other urgent conditions.  Ensure that the maintenance and repair of a surface conform as closely as possible to the original specifications for strength, appearance, texture, and design. Ignoring the original specifications can mean recurring maintenance on areas that are below standard, and differences in wear and traffic impact may result from spot strengthening.
The priority for maintenance and repair depends on tactical requirements, traffic volume, and hazards that can result from failure of the paved area. For example, roads used to support tactical operations should have priority over less essential facilities. A single pothole in a heavily used road that is in excellent condition otherwise should have priority over a less used road that is in poor condition.
 Use any stable material for temporary repairs in combat areas or in areas where suitable material is unavailable and the area must be patched to keep traffic moving. Use good-quality soils and masonry or concrete rubble for this purpose. Ensure that patches are thoroughly compacted and constantly maintained. Permanently patch the area as soon as possible.
Blade the shoulders to facilitate rainwater drainage from the surface, and fill in ruts and washouts. Grade the shoulder material flush against the FM 5-436
Maintaining and Repairing Bituminous Wearing Surfaces pavement edges to restrict water seepage to the subgrade and to prevent the pavement edge from breaking under traffic. Replace material that is displaced from the shoulders with new material as required.
Successful repair with bituminous materials is more likely in warm, dry weather. When breaks occur during cold weather, repair them on a temporary, expedient basis to prevent progressive failures until the weather conditions allow more permanent repairs. Eliminate frost and moisture from the area with surface heaters or blowtorches.

5.     Quality Control Measures During Construction of Road.

All materials to be used, all methods adopted and all works performed shall  be strictly in accordance with the  requirements  of  Specifications.

The Contractor shall carry out quality control tests   on   the materials and work.

 For cement, mild steel, and similar other materials where essential   tests are to be carried out at  the manufacturer's plants or at laboratories other than the site laboratory.

For  testing of cement  concrete  at site    during     construction, arrangements   for supply of samples, sampling,  testing and  supply  of test results shall be made. The  method of sampling  and  testing  of materials  shall be as required by the "Handbook of Quality Control for Construction of Roads and Runways" (IRC: SP: 11), and  these MOST Specifications.

Similarly, the supply of aggregates for construction of road pavement shall   be from quarries approved    by   the   Engineer.

Cement  concrete  pavement:  The    defective   areas   having  surface  irregularity exceeding  3 mm but not greater than  6 mm  may  be  rectified by bump  cutting   or scrabbling  or grinding  using  approved equipment.

Dry lean concrete sub-base:

 Sampling  and   testing   of cubes: Samples   of  dry  lean concrete  for making cubes shall  be taken from the uncompacted material from different  locations  

In-situ density: The dry density of the laid material shall be determined   from three density holes at marked locations

Thickness: The average thickness of the subbase   layer  as computed by the level data of sub-base and subgrade or lower  sub-base shall be as per the thickness specified  in the contract drawings. The thickness  at any single location shall not be 10 mm less than the specified thickness.
Pavement concrete

Sampling and testing of beam and cube specimens: At least two beam and two cube specimens, one each for 7 day and 28 day strength testing shall be cast for ever 150 cu.m (or part thereof)  of concrete placed during construction. On each day's work, not less than three pairs of beams and cubes shall be made for each type of mix from the concrete delivered to the paving plant.

 In-situ density: The   density   of the compacted concrete shall be such that the total air voids are not more than 3 per cent. The air voids shall  be derived from the difference   between   the theoretical maximum dry density of the concrete calculated from the specific gravities of the constituents of the concrete mix. Thickness shall be controlled by taking levels as indicated Thickness of the slab at any point shall be within a tolerance of -5 mm to + 25 mm of the specified thickness as per Drawing. Thick ness deficiency more than 5 mm may be accepted.

No comments:

Post a Comment