feed back

please give me your feed back

Search This Blog

Followers

Thursday, August 26, 2010

My visit to Mahabalipuram(mamallapuram)

Hai,

Recently i visited Mahabalipuram ,the ancient port city of Pallavas .The ancient city Really Enthralled me.

I have no words to explain but i will try to give full view of the ancient (truly these are the pride and honor for Indians) marvelous city.

I have seen Rock cut caves and Temples and See shore temple and other monuments which are built by narasimhavaraman- I and his successors . the period of construction is in between 8 th century A.D to 10 th century A.D.

The see View is also very good and i enjoyed whole day with my childhood friends doctor sreekanth and Gopi.....

if you have a time and if you want see the other end of the world you can visit this gift given by the Pallavas.


Mahabalipuram

Mahabalipuram (Source: Archeological Survey of India, Wikipedia)

Mahabalipuram,derived from 'Mamallapuram' is a town in Kancheepuram district in theIndian state of Tamil Nadu. It has an average elevation of 12 metres (39 feet).
Mahabalipuram was a 7th century port city of the South Indian dynasty of the Pallavas around 60 km south from the city of Chennai in Tamil Nadu. The name Mamallapuram is believed to have been given after the Pallava king Narasimhavarman I, who took on the epithet Maha-malla (great wrestler), as the favourite sport of the Pallavas was wrestling.

Mahabalipuram (or Mamallapuram) was a celebrated port city of the Pallavas. It has been identified as the port Melange mentioned in the Periplus of the Erythraean Sea by an unknown Greek navigator of the first century A.D.

The monuments at Mahabalipuram are of different types like the rock-cut cave temples, monolithic temples, bas-relief sculptures and structural temples besides excavated remains of temples. The Pallava dynasty, which ruled this area between 6th-9th centuries A.D., patronised the creation of these wonderful edifices. Among them, Mahendravarman (AD 580-630), his son Narasimhavarman I Mamalla (AD 630-668), Paramesvaravarman (A.D. 672-700) and Narasimhavarman II Rajasimha (A.D. 700-728) contributed the most in developing Mahabalipuram as a centre of art and architecture. Many monuments remain unfinished.

Cave temples

Varaha cave

General view of Varaha Cave

The mandapa in the front has two lion- pillars and two pilasters, and beyond this in the centre, the cell is guarded by two dwarapalas. There are four panels on the walls of front mandaparepresenting Varaha raising goddess earth from the ocean. (Bhuvaraha panel), Gajalakshmi seated on lotus and bathed by elephants, Durga with four arms and Trivikrama overcoming the demon king Bali. The delineation and modelling of the figures are remarkable.

Bhuvaraha Panel, Varaha Cave

Gajalakshmi Panel, Varaha Cave


Four armed Durga, Varaha Cave

Trivikrama Panel, Varaha Cave

Mahishamardini cave

The cave has a front mandapa with a triple cell with four pillars and two pilasters. On either side of this mandapa two large panels one representing Seshasayi Vishnu and other Mahishamardhini. The central cell is intended for a Siva Linga; on the wall behind is the representation of Somaskanda.

Seshasayi Vishnu Panel, Mahishamardini Cave

Mahishamardini Panel, Mahishamardini Cave

Close up details of Mahishamardini Panel

Dharmaraja Mandapa

The triple celled cave temple with massive pillars belongs to Mahendravarman’s time. The cave temple contains inscription in Pallava grantha which gives the name of the temple asAtyantakama Pallavesvara -griham

Panchapandava mandapa

A large cave temple of which only six lion pillars and similar pilasters at either end are finished. The brackets above the capitals of these pillars are decorated with lions and griffins with human riders. The pillars and Pilasters with vyala base mounted on square pitha

Kotikal Mandapa is a small primitive rock cut temple of Mahendra style devoted to Durga. The façade shows two massive pillars and pilasters at either side end. In the centre of the back wall a cell has been cut and is guarded by female door keepers on either side of the entrance. There is an inscription with 7th century letters-Sri Vamankusa.

Koneri Mandapa

An unfinished five celled rock cut temple with four pillars supported by couchant lions and flanked by pilasters and with a central cell.

Trimurthi cave

A Triple celled temple with superstructure is believed to be dedicated to Brahma, Vishnu and Siva, the three gods of the Hindu pantheon. The entrance of each cell is flanked by dvarapalas in narrow panels.

The Monolothic temples

There are about nine monolithic temples at Mahabalipuram. They are the unique contribution of the Pallavas to Indian Art. The monolithic temples are called locally as Ratha (Chariot) as they resemble the processional chariots of a temple. The Five rathas, the best of all monolithic temples, are hewn out of a huge boulder. Temples of different plan and elevation have been carved and the left over portions were intelligently used to carve animals in a natural way. The naming of these ratha, after Pandavas and their wife, the heroes of epic Mahabharata, is simply a local tradition.

General view of the Monolithic temples, known as Five Rathas, From left to right: Draupadi, Nakula-Sahadeva, Bhima and Dharmaraja Rathas

Dharma raja ratha

Dharma raja ratha

Among the Five rathas, Dharmaraja ratha is the most impressive and sculpturally rich. The tritala (three storeyed) vimana, square in its talas but octagonal in the griva sikhara region, faces west.The sculptures around the sanctum in the corner blocks depict simple forms of Siva, Harihara, Brahma-Sasta, Brahma, a delicately balanced representation of Ardhanarisvara besides a portrait of a king, possibly Narasimhavarman I himself above which his titles Sri Meghaand Trailokiya vardhana-vidhi are inscribed. The upper floors, a veritable gallery of images, have excellently modelled images of Siva as Gangadara, the earliest representation of Siva as Natesa in the Tamil country, Vrishbantika, Kankalamurti, Vishnu resting on Garuda, and Kaliyamardhana. An inscription gives the name of the sanctum in the uppermost tier as Atyantakama Pallavesvaram, Atyantakama being a title of Paramesvaravarman I.

Bhima Ratha

This monolithic ratha is oblong in plan and having an ekatala vimana possibly intended to be dedicated to the reclining form of Vishnu. Only the impressive Sala -Sikhara is fully finished and there is a hara above the ground storey and has high griva wall. The Sala roof carries boldnasikas to carry a row of Stupis and Astradeva trident-finials at the apexes of gable ends. The gable ends is brilliantly relieved with decorative motifs and at the centre is a miniature model of a square, ekatala shrine with circular and crowning stupi.

Bhima Ratha

Arjuna Ratha

This monolithic Vimana is one among five that carved out of a live rock. This small dvi-tala (two tiered) vimana consists, on plan a garbhagriha with a pillared Mukhamandapa. It shares an Upa Pitha with Draupathi ratha. The adhisthana is of simple Padabandha type. The pada portion has slit-niches between elegantly carved pillars carrying very handsome figures of Parthiharas,Amaras, a Siddha, a Chowri bearer, apsaras, and various deities like Vishnu, Skanda on elephant and Siva-Vrishabhantika. The upper tala (Storey) carries a hara with octagonal sikhara. There is a stupi carved out of the live rock but not detached from it, possibly to crown the Sikhara of the Vimana.

Arjuna Ratha

Draupathi Ratha

This is the smallest and the northern most of five monolithic rathas. It illustrates a simple hut-likeKutagara-Vimana. It shares an upapitha with Arjuna ratha. In elevation, the vimana has a simple padabandha adhisthana. The pada portion has devakoshtas containing images of Durga. The usual kapota is not to be seen. The roof, shaped like a hut with decorative motif in the joints. There is stupi carved out of the bedrock in a corner of the upapitha but yet to be detached from it. The sanctum bears an excellent depiction of Durga, possibly of later period.

Draupadi Ratha

Sahdeva Ratha

This monolithic ratha has an apsidal (Gajapriishta) plan from base to sikhara, recalling the earlierchaitya models. It is carried out of an independent boulder, stands near the Arjuna ratha and faces south. It has a dvitala vimana (two storeyed). The adhistana of this vimana is not defined. The pada is simple punctuated by pilasters. There is a mukha- mandapa in the front.

Sahadeva Ratha


The other monolithic temples worth mentioning are Ganesha ratha and Pidari ratha.

Ganesha Ratha


Arjuna Penance

Arjuna’s penance is an impressive bas-relief, datable to Narasimhavarman I’s period, suggestively depicts the story of Kiratarjuniya, wherein Arjuna, the great warrior hero of the Mahabharata, obtained the all-pervading Pasupatha weapon from Siva after a gruelling fight and severe penance. Siva and an emaciated Arjuna, doing penance, are shown prominently at the centre. The artist has excelled in imagination by placing the scene by the side of a river, judiciously suggesting the natural cleft as a river by depicting a naga and nagini. The peace and calm of the situation further enhanced by the presence of Chandra, Surya, Kinnaras, Ghandarvas, Apsaras etc., hunters carrying the hunt, host of animals, sages doing penance in front of a temple and Brahmins doing the mid-day rituals. The deer resting at ease by the side of a lion and the rats frolicking around the wily cat doing penance on hind legs have only enhances the mood. Depicting the animals in the most natural form and in right proportion is a testimony to the skilful execution by the artist.

Arjuna's Penance Panel

Govardhanadhari Panal

Govardhanadhari Panel

The huge bas-relief with a hall (mandapa) of 16th century added in front depicts the story of Krishna lifting the Govardhana hill to protect the cowherds and the cattle from the storm raised by Indra. The central figure of Krishna, with Balarama by his side, is shown lifting the hill with his little finger. Enjoying the divine protection, the rest are carrying on their business as usual. The artist suggests this by depicting a gopa (cowherd) milking a cow while the cow itself is fondly licking its calf. Another cowherd is seen playing a flute while the gopis carry a pile of pots. A woodcutter strolls with an axe. While one child enjoys the warmth of her mother, another takes a ride over the shoulder of an old man. The hill itself is a habitat for lions, griffins and sphinxes. This is the best representation of this story in the art of India.


Structural temples

Among the structural temples, the Shore temple consisting of two graceful Siva temples –Kshatryasimhesvaram (east) and Rajasimhesvaram (west), built by Pallava King Rajasimha (AD 700-728), mark the culmination of the architectural efforts begun with the carving of monolithicrathas. The western shrine has an outer wall (prakara) and a simple entrance tower (gopura). The elevation is gracefully proportioned. Located in between is an earlier shrine for reclining Vishnu (Narapatisimha Pallavagriham). It has no superstructure.

Shore Temple

All the names of these shrines represent Rajasimha’s various titles. The outer enclosure withnandis is of later period. Fully aware of inherent problems of this scenic location, the architects built the temple on a rock outcrop jutting from the sea. The use of hard stones like granite and leptinite, could not stop the erosion by abrasive wind and salty surroundings. The groyne wall, the plantation and periodic extraction of salt in recent times have checked this effect. The outcrop itself was utilized for carving several masterpieces like the excavated miniature shrine, Bhuvaraha image, Vishnu shrine, and the Mahishamardhini shrine with the beautifully carved deer.

Other structural temples worth mentioning are the Mukundanayanar and Olakkanesvara temples.

Excavated Remains

Sustained removal of the sand in the last century brought to light several buried structures around the Shore temple. Unique among them is the early Pallava stepped structure, approximately 200 m long. This structure is running north to south parallel to the sea. The exact purpose of this massive edifice is still uncertain. The steps are built of interlocking granite slabs over a laterite core. The intelligent interlocking method used here prevented the slabs from collapsing and recalls the megalithic traditions.

Stepped structure in front of Shore Temple

Accidentally discovered in 1990, the Bhuvaraha image, the miniature shrine and the well belongs to Pallava King Narasimhavarman Mamalla’s (AD 638-660) reign, but enclosed by an elliptical enclosure of Rajasimha’s (AD 700-728) period. These remains are carved on the live bedrock containing the reclining Vishnu.

Miniature Shrine to the north of Shore Temple

Close up details of Miniature Shrine and Varaha


The miniature shrine, dedicated to Siva, has its sixteen-side base carved out of the bedrock while the circular wall and superstructure are structural. Its form is unique and differs from all other single tier temples of Pallava period. The Bhuvaraha is shown retrieving the Mother Earth symbolically from the deep ocean. It was intentionally broken for unknown reasons. The base is inscribed with titles of the Pallava king Rajasimha. The enclosure wall built possibly to arrest sand from covering the remains contains an inscription in Pallava-Grantha script on the topmost course equating the king in pun with Arjuna.

Recently, remains of two temples were excavated, one to the south of Shore temple and another massive brick temple of Subrahmanya near the Tiger Cave at Saluvankuppam, a hamlet about 7 km from here.

Subrahmanya Temple, Saluvankuppam, view from north

Subrahmanya Temple, Saluvankuppam, view from south

Ticket Rates:

  • For Shore temple and Five rathas: Rs. 10 for Indian citizens and Rs.250/- or US $ 5 for others. Admission is free for all below the age of 15

  • A ticket purchased at one monument is valid at the other

  • Admission to the rest of the monuments located in the hillock area and other places is free as of now

  • No fee for still photography with handheld cameras.

  • Rs. 25/- for videography with handheld cameras. A simple form may be filled at the counter to get permission

  • For all other types of photography and videography, the Superintending Archaeologist, A.S.I ,Chennai Circle, Chennai-9 may be contacted (Ph. 044- 25670396/25670397)

Hours of opening:

0600 hrs to 1800 hrs on all days. Sale of admission tickets will be closed at 1730 hrs.

Approach:

Mahabalipuram is about 58 km from Chennai on the East Coast Road and well connected by public and private transport. The nearest airport is located at Chennai.

Photo Gallery

023

Surya, monument known as Dharmaraja ratha, east wall, 7th century A.D.

005

Monkey group, Arjuna's penance, 7th century A.D.

012

Seshasayi Vishnu, Mahishamardini cave, 7th century A.D

013

Devi killing Mahisha, Mahishamardini cave, 7th century A.D.

Map : Mahabalipuram

Group of Monuments at Mahabalipuram

Friday, August 20, 2010

Hampi - My favorite Tourist Spot



Hampi

Hampi is a village in northern Karnataka state, India. It is located within the ruins of Vijayanagara, the former capital of the Vijayanagara Empire. Predating the city of Vijayanagara, it continues to be an important religious centre, housing the Virupaksha Temple, as well as several other monuments belonging to the old city.

The name is derived from Pampa, which is the old name of the Tungabhadra River on whose banks the city is built. The name "Hampi" is an anglicized version of the Kannada Hampe(derived from Pampa). Over the years, it has also been referred to as Vijayanagara and Virupakshapura (from Virupaksha, the patron deity of the Vijayanagara rulers).

Hampi is identified with the historical Kishkindha, the Vanara (monkey) kingdom mentioned in the Ramayana. The first historical settlements in Hampi date back to one CE.

Hampi formed one of the cores of the capital of the Vijayanagara Empire from 1336 to 1565, when it was finally laid siege to by the Deccan Muslim confederacy. Hampi was chosen because of its strategic location, bounded by the torrential Tungabhadra river on one side and surrounded by defensible hills on the other three sides.

The site is significant historically and architecturally. The topography abounds with large stones which have been utilized to make larger than life statues of Hindu deities. A structure of historic importance appears every quarter of a mile. The Archaeological Survey of India continues to conduct excavations in the area, to discover additional artifacts and temples.

Geography

Hampi is situated on the banks of the Tungabhadra river. It is 353 km from Bangalore and 74 km away from Bellary. Hosapete (Hospet), 13 km away, is the nearest railway head. The chief languages spoken are Kannada and Telugu. The principal industries of the village areagriculture, the support of the Virupaksha temple and some other local holy places in the vicinity, and tourism. The annual Vijayanagar Festival is organized by the Government of Karnataka in November.

Due to the presence of several mineral deposits in this region (iron-ore, manganese), mining has been going on for many years now. But a recent boom for the supply of iron-ore in the international market has led to excessive mining in this district. The World Heritage Site at Hampi as well as the Tungabhadra Dam are now under threat.

Important sites at and near Hampi


Temples

Hampi has various notable Hindu temples, some of which are still active places of worship. Most notable ones are:Virupaksha Temple complex: Also known as the Pampapathi temple, it is a Shiva temple situated in the Hampi Bazaar. It predates the founding of the Vijayanagar empire. The temple has a 160-foot (49 m) high tower at its entrance. Apart from Shiva, the temple complex also contains shrines of the Hindu goddesses Bhuvaneshwari and Pampa.








Hampi - the story that unrevealed

HAMPI- THE VIJAYANAGARA KINGDOM

Saint Vidyaranya established the seat of Vijayanagara empire in 1336 A.D, with the help of his devotee disciples Hakka and Bukka. The empire later became famous for its support towards renovation/reconstruction of temples through out India. It also became renowned for re-establishment of Indian culture, its support for music, art and literature. With the prime purpose of caring for the people and their welfare, this empire stretched physically covering Karnataka, Andhra and Maharashtra and became a by-word for golden rule.



Inside Vittala Temple

HAMPI, the seat of the famed VIJAYANAGARA empire was the capital of the largest empire in post-mogul India, covering several states. The empire reigned supreme under Krishnadevaraya, the Emperor. The Vijayanagara empire stretched over at least three states – Karnataka, Maharashtra, and Andhra Pradesh. The destruction of Vijayanagar by marauding Moghul invaders was sudden, shocking and absolute. They reduced the city to ruins amid scenes of savage massacre and horrors beggaring description.

Narasimha Monolith

Virupaksha Temple

The Ruins of Vijayanagara

Although in ruins today, this capital city once boasted riches known far beyond the shores of India. The ruins of Hampi of the 14th Century lies scattered in about 26 sq. km area, amidst giant boulders and vegetation. Protected by the tempestuous river Tungabhadra in the north and rocky granite ridges on the other three sides, the ruins silently narrate the story of grandeur splendor and fabulous wealth. The splendid remains of palaces and gateways of the broken city tells a tale of men infinite talent and power of creativity together with his capacity for senseless destruction.

Stepped Tank

Street view Of Vijayanagara Kingdom

View of Chariots

Strewn over a large area (about nine square miles) the ruins at Hampi offers to the tourist a remainder of the greatest land in the whole world. Every rock, every path and every monument at Hampi speak the same language; a language of glory and beauty.

View of Virupaksha Temple

The Chariot ( Beautiful Art)

Inside Virupaksha Temple (Musical Stones)


View from Virupaksha temple (Vijayanagara)

Stone Sculpture vishnumurthi

Ruined Temple

The Rathas

In March 2002, the Government of India has announced that Hampi would be developed as an international destination centre. The State Govt will constitute a Hampi World Heritage Area Management Authority for integrated development and conservation of Hampi.





Hampi - the story that unrevealed

Lotus Mahal In Hampi



Wednesday, August 18, 2010

When i was a child i was listen to my father about Hampi, he told me about the greatness of Sri Krishnadevaraya and the beauty of Vijayanagara Kingdom, the picture above is virupaksha Temple in Hampi(Vijayanagara).

Thursday, January 28, 2010

Pavemnt analysis and design III

1.3. INNOVATIVE APPLICATIONS

Innovative applications may be construction method based or design principle based. Some of the relevant issues are discussed in the following.

1.3.1 Construction Method Based

A mixture of aggregate and binding material, at varied proportions, constitute various specifications for road construction, for example, bituminous concrete, built-up spray grout, wet mix macadam, lean cement concrete etc. Discussion on all these standard specifications have been skipped here, rather, some specific mixes and their construction methods are discussed.

Emulsified bituminous mix

Cold emulsified bituminous mix (EBM) is gaining more and more acceptance for its environmental friendliness and less hazardous construction process. A relative comparison between the EBM and hot bituminous mix (HBM) has been presented in Table 4. It may be noted that though the rate of strength gain in EBM is slower (refer Figure 7), the final strength of EBM is comparable to that of HBM.

Table 4. Comparison of hot bituminous mix (HBM) and emulsified bituminous mix (EBM)

Property

HBM

EBM

Heating

Strong heating required, oxidative hardening occurs

No heating required, so no oxidative hardening

Setting time

Low

High

Applicability

Clear weather with high ambient temperatures

All weather (wet surfaces, rainy seasons, cold)

Convenience

Relatively difficult construction than EBM

Relatively easy construction

Energy

Relatively higher requirement

Relatively lower requirement

Uniqueness

Modifiers needed

Inherent anti-stripping agents

Economy

Less costly

More costly

Safety

Hazards from fuming, fire and environmental pollution

Free from such hazards

Foamed bituminous mix

  • Foamed bituminous mix (FBM) is a foamed mixture of air, water and bitumen. It is produced by injecting very small quantity of water into the hot bitumen, resulting in spontaneous foaming and temporary alteration of the physical properties of the bitumen. Figure-8 represents schematically the manufacture of FBM.
  • Although the foamed bitumen technology was developed more than forty years ago, it is now gaining popularity owing to its good performance, ease of construction and compatibility with a wide range of aggregate types (Transportek 1998).
  • Usage of FBM results in reduction in binder content and transportation costs, as it requires less binder and water than other types of cold mixing methods.
  • FBM can be compacted immediately and can carry traffic almost immediately after compaction is completed ( Jenkins et al., 2003 ).
  • The strength characteristics of FBMs are highly moisture dependent. This is because of the relatively low binder content and high void content of foamed bituminous mixes.
  • FBMs are not as temperature susceptible as HBM. Since larger aggregates are not coated with binder, the friction between the aggregates is maintained at higher temperatures.
  • Foamed bitumen can achieve stiffness comparable to those of cement-treated materials, with the added advantages of flexibility and fatigue resistance (Ramanujam and Kendall, 1999).
  • FBMs usually lack resistance to abrasion and raveling and are not suitable for wearing/friction course applications.

Figure - 8 Schematic presentation of FBM manufacture ( Romanoschi 2003 )

Some specific situations where use of foamed bitumen technology can be considered are:

• A pavement which has been repeatedly patched to the extent that pavement repairs are no longer cost effective.

• A weak granular base overlies a reasonably strong subgrade.

• Granular base too thin to consider using cementations binders.

• Can be effectively used in desert road stabilization etc. (Jenkins et al., 2003).

Relatively high cost, requirement of specific equipment for mix production, sensitivity to aggregate grading and stripping risk are some of the disadvantages with the foamed bituminous mix ( Jenkins et al., 2003 ).

Fiber reinforced bituminous mix

Addition of various kinds of fibers to the binder and aggregates during mix preparation process results in fiber reinforced bituminous mix (FRBM). Fibers are generally blended with bitumen binder before mixing it with the aggregates to achieve complete coating and even distribution throughout the mix. Research shows that FRBMs develop good resistance to aging, fatigue cracking, moisture damage, bleeding, reflection cracking etc. (Serfass and Samanos, 1996; Maurer et al., 1989).

Ultra-thin white topping

Overlaying technique of pavement rehabilitation is well known and widely practiced. However, ultra thin whitetopping (UTW) of concrete over existing bituminous pavement is a relatively new concept. UTW can be designed for low-speed, low volume traffic areas such as street intersections, aviation taxiways and runways, bus stops and tollbooths.

In this technique, a thin layer of high-strength, fiber-reinforced concrete is placed over a clean, milled surface of distressed bituminous concrete pavement to achieve a full or partial bonding. Bonding makes the two layers behave as a monolithic unit and share the load. Due to bonding, the neutral axis in concrete shifts from the middle of concrete layer towards its bottom. This results in a lowering of stresses at the bottom of concrete layer. Thick composite section behavior causes the corner stresses to decrease. On the other hand, downward shifting of neutral axis may cause critical load location to shift from edges to corners thus increasing the corner stresses. Short joint spacing is used to decrease the slab area that can curl or warp thus minimizing the corresponding stresses (MTTP 2004). A schematic diagram of UTW have been presented inFigure-9.

Figure -9 Flexible composite pavement using UTW

UTW is an excellent resurfacing option for deteriorated bituminous pavements which otherwise require frequent repair or overlays.

Following are some of the advantages of a UTW system (CAC 2004, Murison 2002):

• It is beneficial for repair of roads and intersections having problems of rutting, cracks, and poor drainage.

• It provides improved skid resistance.

• Its light colour reflects more light than bituminous pavement.

• Its heat-reflecting property can help to lower the average city temperature.

• It is less costly to maintain, than conventional flexible pavements, and does not require frequent resurfacing and repairs.

• The UTW concrete resists bitumen aging.

• The UTW concrete prevents degradation of bituminous surface due to fuel spills.

• It causes minimal traffic disruption due to faster construction and repair procedure.

• Its small panels are ideal for utility maintenance.

Bituminous recycling

In recycling method, bitumen and aggregates are separated out (partly or fully) and used again. The specific benefits of recycling of bituminous pavement can be summarized as:

  • Conservation of energy and construction material.
  • Prevention of undesirable rise in height of finished surface and preservation of the existing road geometrics.
  • Reuse of deteriorated road materials which in turn solves the disposal problem.
  • Solution to the problem of scarcity of good quality material.
  • Preservation of the environment.
  • Reduction in susceptibility to reflection cracking.

Bitumen ages due to oxidation with atmospheric oxygen as a result of which resins get converted into asphaltenes (Petersen, 1984). By this process bitumen loses its ductility and becomes more brittle. Recycling is based on the fact that bitumen obtained from old deteriorated bituminous pavement, may still has its residual properties and recycling helps in restoring those residual properties of the bitumen.

To judge the suitability for use as a recycled material, aggregates are tested for their gradation and bitumen is tested for its engineering properties. The optimum quantity of reclaimed material to be mixed with fresh material is generally determined from mix design process. Fresh thin (soft grade) bitumen having low viscosity can be used to replenish the aged bitumen. Rejuvenators (like road oils and flux oils) are sometimes added for improvement in properties of reclaimed bitumen.

There are four major technologies exist for bituminous pavement recycling (NCHRP-452). They are

(i) Hot mix recycling

Here recycled asphalt pavement ( RAP) is combined with fresh aggregate and bituminous binder or recycling agent in a hot mix plant. Mix is transported to paving site, placed, and compacted.

(ii) Cold in-place recycling

In this the existing pavement is milled up to a depth of 75 to 100mm, RAP, if necessary and recycling agent in emulsion form is introduced, and then compacted.

(iii) Hot in-place recycling

In hot in-place recycling method the existing asphalt surface is heated, scarified to a depth from 20 to 40 mm, scarified material combined with aggregate and/or bituminous binder and/or recycling agent and compacted. New overlay may or may not be provided.

(iv) Full depth reclamation

Here all the bituminous layers and predetermined thickness of underlying material is pulverized, stabilized with additives, and compacted. A surface course is applied over it.

Semi flexible grouted macadam

  • Grouted Macadam consists of a single sized porous bituminous layer whose voids can be filled with the selected fluid grout or cementations slurry.
  • The porous bituminous skeleton is designed to achieve a high void content while maintaining a thick bitumen coating on the aggregate particles (Zoorob et al., 2002).
  • Grouted macadam gives advantages of both flexible and rigid pavements namely,

• Flexibility and absence of joints by use of bitumen,

• High static bearing capacity and wear resistance (as for concrete) by use of cementations grout.

Micro-surfacing

  • Micro-surfacing is a fast and economical surface treatment technique used for preventive maintenance of bituminous and cement concrete pavements.
  • Polymer modified emulsion, cold blended with fine graded aggregates, mineral fillers, additives and water, gives the high performing micro-surfacing mixture.
  • Micro-surfacing is generally used to restore the top wearing surface of pavement as a maintenance measure, thereby extending the pavement life.
  • Its thickness may be varied to achieve desired objective(s) such as rut-filling, skid resistance improvement, surface sealing, surface texturing, noise reduction, repairing abraded wheel path channels etc (ODOT 2004; Miller 2004).

Design Principle Based

This section discusses about the design principle based innovative applications of road materials. Discussion has been divided into two parts viz.

  • Structural design considerations, and
  • Mix design considerations

Optimum pavement design thickness

In Mechanistic-Empirical pavement design, generally sustainability of a pavement structure against fatigue and rutting failures is considered, for which the critical responses are: (a) the tensile strain at the bottom fiber of bituminous layer and (b) the vertical strain at the top of the subgrade. A number of design thickness combinations of bituminous and granular layers are possible which satisfies the above mentioned requirement.

Standard design charts developed by various organizations (Shell 1978; Austroads 1992; Asphalt Institute 1981; IRC:37-2001) are available; these design charts generally provide thickness composition of bituminous and granular layers, depending upon other input parameters viz. temperature, traffic, design life, subgrade strength, material type etc. A designer can choose any suitable granular layer thickness, and, corresponding thickness of bituminous layer can be read from these charts.

Figure 10. Typical pavement design chart

POINT A - Safe from rutting but over safe from fatigue considerations.

POINT B- Safe from rutting but unsafe from fatigue considerations.

POINT C- Safe from fatigue but insafe from rutting considerations.

POINT D- Safe from fatigue but oversafe from rutting considerations.

POINT E - Unsafe from both rutting and fatigue considerations.

Point F- Oversafe from both rutting and fatigue considerations

POINT O- Just safe from both rutting and fatigue considerations.

Figure 10 illustrates a typical design chart. The design chart consists of two curves: fatigue curve and rutting curve. The fatigue curve shown as COD in Figure 10 represents the points, which are just safe from fatigue consideration. Similarly, the rutting curve shown as AOB in Figure 10 represents those points which are just safe from rutting consideration. Figure 10 shows various points like A, B, C, D, etc. They are safe, oversafe or unsafe from fatigue or rutting considerations. The reader can point the cursor on the respective points to know about their status. In the design chart the fatigue curve and the rutting curve intersects at a point (point O in this case) that may be called as structurally balanced design point (Narasimham, et al., 2001). Thickness of pavement layers chosen according to this point will result in a pavement deign which would fail due to fatigue and rutting simultaneously. Similarly, there could be cost optimal point, where bituminous and granular layer thicknesses are selected such that the total cost of materials used is minimized, without compromising with the structural adequacy of the pavement. The cost optimal point may or may not coincide with the structurally optimal point (Narasimham et al. 2001, Das 2004 ).

Perpetual pavement

A perpetual bituminous pavement may be defined as a pavement designed and built to last longer than fifty years without requiring major structural rehabilitation or reconstruction (APA101 2001). This pavement may only require periodic replacement of top wearing surface and recycling of old pavement material (TRL 2001; AA-2 2001).

The concept of full depth bituminous pavement is in vogue from 1980s in USA. Nunn and his associates of Transport Research Laboratory, UK found (Nunn et al., 1997) that thick bituminous pavements tend to show long lasting performance and may require only minor surface repairs. California Department of Transportation in collaboration with University of California, Berkeley (Monismith et al., 2001) first implemented concept of perpetual pavement in a rehabilitation planning project.

In full depth bituminous pavement, the thickness is so designed that the fatigue and rutting strains developed are below the permissible limit (MS-1 1999 ). If the thickness is chosen to be sufficiently large so that the fatigue strain is close to the endurance limit, then the fatigue life becomes very long, and the pavement may be said to have attended 'perpetual life'. A perpetual pavement, in general, is made up of the following layers:

  • The top wearing surface is designed in such a way that it is water-tight as well as removable and hence replaceable. Stone Matrix Asphalt (SMA) or Open Graded Friction Course (OGFC) are recommended. They also produce less noise due to tyre-pavement interaction.
  • The intermediate layer is constituted with good quality aggregates and designed to be strongly resistive to rutting.
  • The bottom part is made resistant to fatigue cracking by making it rich in bitumen and choosing a gradation that has less voids.

Figure 11 Layer composition of a perpetual pavement.

Figure-11 schematically represents the layer composition of a typical perpetual pavement.

A perpetual pavement is a full depth bituminous pavement in most of the cases. The principles based on which it is designed (mix design and structural thickness design) are the following:

  • The pavement layers are chosen in such a way that they are rut resistive. The pavement is chosen to be adequately thick such that the vertical subgrade strain is low. Since subgrade contributes to the major part of rutting, low vertical subgrade strain would cause low level of rutting.
  • The wearing surface should be adequately water-proof. The surface should be so designed that it can be repaired or recycled and the whole pavement will not require any major reconstruction (AA-2 2001).
  • The thickness of the bituminous layer is chosen in such a way that the horizontal tensile strain (εt) developed is less than the endurance limit (refer Figure-12) of the bituminous mix, hence its laboratory fatigue life (N) becomes infinity (AA2-2001, Nunn et al. 1997). It is justifiable to design the pavement as 'bottom rich' (refer to next section), which shifts the endurance limit to higher level.
  • The temperature gradient tends to be steeper towards the surface of the pavement (TRL 2001,Newcomb 2001) as shown schematically in Figure-12. Therefore the bituminous mixes with temperature susceptible binder should be avoided as surface course. Use of modified binder could be helpful in this regard.

Figure 12 Idealized diagram of fatigue characteristics of bituminous mixes.

Rich bottom bituminous pavement

Increased binder content above the optimum content can appreciably enhance the fatigue life.

Higher bitumen content increases the thickness of the binder film between aggregates resulting in lower stress in the binder film, and thus the fatigue life is improved (Sousa et al., 1998; Harvey et al., 1996).

However, with increased amount of binder content, the bituminous mix tends to be softer and thereby its stiffness modulus value may fall.

A mix designer's objective would be to achieve both high stiffness and high fatigue life.

This mutually contradictory situation can be handled by using a bituminous pavement layer where it is made richer in binder content towards the bottom layer(s).

Since fatigue cracks start from bottom of bituminous layer, higher bitumen content helps to give greater restraint against fatigue cracking.

This concept has been termed as 'rich bottom pavement' (Monismith et al., 2001; Harvey et al., 1997; Harvey and Tsai 1996).

Figures 13 and 14 provide two such options of achieving this condition. In Figure-13, quantity of bitumen is used more towards the bottom of the layer. In Figure-14, two different bituminous mixes are used in two layers. Out of three possible alternatives, alternative-II turns out to be the best alternative.

Figure 13 Rich bottom pavement

Figure 14 Two grades of bitumen used in two layers

Inverted pavements

  • Inverted pavement system, or inverted base, is a high depth pavement whose supporting layers are thicker and stiffer than top layers.
  • The system consists of a thin bituminous concrete (BC) layer provided on top of a graded aggregate base (GAB) layer. A Portland cement-treated stiff base layer is provided at the bottom.
  • This arrangement causes the critical stress/strain plane to be located at the interface of the BC and GAB layers. Thus only the top portion of the inverted pavement structure absorbs the traffic loads as compared to conventional design where thick sections are required for load distribution.
  • Research by South African Roads Board (SARB 2004) and Georgia Department of Transportation, has shown that an inverted base provides enough structural performance to support traffic loadings up to 100 million Equivalent Single-Axle Loads (ESAL s) with a maximum two inch bitumen riding course (Halsted, 2002). According to SARB, this type of system proves to be more cost effective for construction of long lasting pavements.
Bituminous pavement with cemented base
  • The cemented bases are derived from aggregates mixed with some binding material. Since it is bounded layer, it also has some fatigue life.
  • Thus, unlike the unbound granular base, the cemented base layer contributes to some fatigue life, which may give rise to comparative reduction of design thickness of bituminous layer (Das and Pandey 1998).
  • The stiffness modulus of cemented layer is generally found to be much higher than granular sub-base; however, due to shrinkage cracks, the stiffness modulus falls rapidly.
  • This change in stiffness values at different stages of the design life has been schematically shown in Figure-15(a) and Figure-15(b) presents a typical design chart for design of bituminous pavement with cemented base made up of lime-soil mixture.

15 (a) Change of elastic modulus of cemented bases at different phases.

15 (b) A typical design chart of bituminous pavement with cemented base (LS º lime soil)

Mix design considerations

Non-standard gradation

The fatigue life of the mix can be increased by increasing the bitumen content.

But, Voids in Mineral Aggregates (VMA), being fixed for a given gradation and compaction level, increase in bitumen content will result in less Air Voids (VA), which is undesirable for a mix.

However one can deviate from the specified gradation in order to come up with a new gradation, which possibly can give rise to better fatigue performance, yet without compromising with the VMA and Marshall-stability requirements.

Stone matrix asphalt

Stone matrix asphalt (SMA) is a gap-graded bituminous mix with high percentage of coarse aggregates with high bitumen content. Gap gradation aims at maximizing stone-to-stone contact. This gives a structurally strong mix due to efficient load distribution through the stone-matrix skeleton. The drawback of this method is the absence of medium sized aggregates due to gap gradation. This may arise possibility of drain-down of low-grade penetration bitumen through the stone matrix. To check this possibility, modifiers, such as cellulose fibers, are used to hold the bitumen in place (Better Roads 2003; GDOT 1995; Decoene et al., 1990).

Porous pavement

  • Porous pavement is a special type of pavement which allows surface water to pass through it, thereby keeping the road surface water-free, as well as providing drainage outlet to storm water.
  • Porous pavement may be effectively used in light traffic areas like parking areas, airport taxiway and runway shoulders, footpaths, playgrounds etc. provided that the subsoil drainage, groundwater level and topography of the area is suitable (Michele, 2003; USEPA 1999; DEQ 1992).
  • Pavement structure consists of a top porous bituminous layer placed over a filter layer below which a highly permeable open-graded stone layer (known as reservoir course).
  • A geotextile layer is placed at the bottom to screen off fine soil particles. Porous bituminous layer consists of gap-graded aggregates (lower percentage fines), held together by a fiber-bitumen blend, giving a matrix structure which allows movement of water through its fine voids.
  • Besides load bearing, the reservoir course stores the runoff water (in the void spaces in aggregate layers) until it can infiltrate into the soil beneath.
  • Porous pavement has been found (RPL 2001) to be quite effective in reducing noise levels, splash and spray during rains, and aquaplaning tendency thereby improving the wet skid resistance.

CLOSING REMARKS

Certain standard methods are followed for road design and construction. They are modified from time-to-time to match with the technological advancements. Certain modifications in the mix design or structural design can give rise to substantial economy in terms of the longevity of the pavement or the cost of the material concerned.

Cement is manufactured by heating a mixture of limestone, iron ore, gypsum, clay and other ingredients. Cement concrete is a mixture of coarse aggregates, fine aggregates, cement and water, in suitable proportions. Through mix design, suitable proportions of the ingredients of concrete are estimated considering strength, workability, durability and economics. Workability test and air-content test are the tests generally conducted on fresh concrete. Compressive strength, tensile strength, modulus of rupture, elastic modulus, Poisson's ratio, creep and shrinkage, durability, thermal expansion coefficient etc are the tests conducted on hardened concrete.

Various modifications and innovatory applications of pavement materials and pavement design brings in better performance and economy.