The document discusses laterite, a type of weathered rock found in tropical regions that has traditionally been used as a building material in India. It provides background on laterite formation and properties. It then describes several examples of historic laterite buildings in India, including prehistoric megaliths, maritime forts from the 15th-18th centuries, religious structures, and traditional residences. The document also discusses laboratory experiments that examined laterite's weathering mechanisms and properties like compressive strength. It finds that laterite is sensitive to salt crystallization and weathering can be reduced by protecting weaker laterite from damp conditions.

1. LATERITE
MANU MALIEKAL
PRASHINPRASHANTH
MALAVIKA M
ATHIRAD
AMRITAS
Abdulla farhan

2. Background
The rich Architecture of India is a
reflection of geological diversity of
the nation. Indigenous architectural
styles and construction techniques
were evolved utilizing locally
available building stones.
Objectives:
• Laterite formation
• Weathering issues
• Conservation strategies
• Laterite buildings

7. LATERITE STORY
Of the various soil types that occur in the tropics and sub-tropics,
laterites are
of special interest in conjunction with building construction. These
are highly
weathered soils, which contain large, though extremely variable,
proportions
of iron and aluminium oxides, as well as quartz and other minerals.
They are found abundantly in the tropics and sub-tropics, where they
generally
occur just below the surface of wide grasslands or forest clearings in
regions
with high rainfall. The colours can vary from ochre through red,
brown, violet to
black, depending largely on the concentration of iron oxides

8. • Soft occurrences tend to harden on exposure to air, which is why
blocks have traditionally (eg in India) been cut in situ, allowed to
harden and then used for masonry wall construction (hence the
name was derived from “later”, the latin word for “brick”).
• The darker the laterite, the harder, heavier and more resistant to
moisture it is.
• Some laterites are found to have a pozzolanic reaction when mixed
with lime (which can be explained by the high clay content),
producing hard and durable
building materials (eg stabilized blocks).

9. Outline of Presentation
• Laterite- Background
• Laterite Monuments in India
– Prehistoric megaliths
– Maritime Forts
– Religious monuments
– Traditional residences
– Ancillary structures
• Laterite – Properties and weathering
mechanisms
• Conservation Strategies
• Summary & Conclusions

10. World wide distribution of laterite
– Laterite: weathered rock found in tropical and subtropical humid
regions of the world.
– Major part of the Indian peninsula, which falls within Koppen’s ‘A’
climate, is subjected to formation of laterite

11. About laterite…
• Laterite, tropical weathered rock, defined for the first time by
Buchanan(1807) as a versatile building material of Malabar region of
India
• It is considered as metasomatic rock (different from other type of
rocks) altered form of other rock types- igneous, sedimentary or
metamorphic
• Laterite is treated as a weak rock for building applications; also as a
soil group. Methods of testing-different from other rock types
• Cost effective, energy efficient and environment friendly
building material in Malabar region of Kerala
• Good aesthetics, easiness to cut and hardening with age,
makes it unique compared to other natural stones

12. Significance of Malabar laterite
National Geological Monument at
Angadipuram, Kerala
Definition of Laterite in
Malabar: later-ite meaning
“brick-stone” by Buchanan in
1807

18. Laterite Quarrying
• Quarrying of laterite using rotary saw machine
• Standard size specified by IS codes

19. Laterite Quarrying
Quarrying of laterite using mobile
rotary saw machine
Obtaining laterite blocks of
standard size from the same strata
Obtaining laterite specimens from
quarry

21. Decrease in
iron content
with depth
and increase
in silica and
aluminum
(clay) content
was seen in
the profile.
Typical laterite profile: Characteristics

24. Prehistoric Megaliths( 2nd Cent B.C-1st Cent A.D.)
Pre-historic burial sites-lateritic
zones
• Umbrella stones (kudacallu)
• Cap stones (Thoppicallu)
• Hood stones
• Caves ( muniyaras)
• Dolmens and menhirs
Protected monuments –Archaeological survey of India

25. Group of Umbrella Stones ( kodakkallu), Trichur
(ASI Protected Monuments)
Prehistoric Megaliths ( 2nd Cent B.C-1st Cent A.D.)

26. Maritime Forts of Malabar
• Bekkal Fort, Kasarkode (16th Century)
• Tellicherry Fort ( 18th century)
• Fort St. Angelo, Kannur ( 15th Century)
These heritage monuments and natural sites with its environmental settings has
been recommended by ASI to include in the World Heritage list of UNESCO

27. Bekkal Fort – A Tourist Destination
BEKKAL FORT, KERALA, W.India-
(16th Cent. A.D.)

28. Bekkal Fort, W.India
BEKKAL FORT, KERALA

29. Bekal Fort, Kasarkode
BEKKAL FORT, KERALA

30. Bastions and Fort walls facing sea
Bekkal Fort, Kasarkode, Kerala

31. Raised Bastion , Bekkal Fort, Kerala, India
Bekkal Fort, Kasarkode, Kerala

32. Main entrance from the road
Bekkal Fort, Kasarkode, Kerala

33. Tellicherry Fort- Entrance Structure
Tellicherry Fort ( British 18th Cent A.D.)

34. 12m High Wall in laterite Tellicherry Fort
Tellicherry Fort, Malabar, India

36. Tellicherry Fort: Adjoining Areas

37. The Fort was built by the Portuguese in 1505
Fort St Angelo, Kannur : Main Entrance

38. View towards the Sea from the Fort- Cannons pointing towards sea
Fort St Angelo, Kannur 15th Century

39. Fort St Angelo, walls abutting the Arabian sea

40. Fort St Angelo, Kannur

41. Fort St Angelo, Kannur

42. Vaulted Structures in Laterite, Fort St Angelo
Fort St. Angelo- Horse stables within the fort

43. The Vaulted structure- Horse
stables
Fort St Angelo, Kannur

45. Fort St. Angelo- The Prison cells within the
Fort

46. Thick Fort Walls – Laterite Ashlar Masonry
Fort walls- Laterite Ashlar masonry

47. Church Within the Fort. St Angelo
Fort St Angelo- Church building within the Fort

48. Maintenance work by ASI- Fort St. Angelo
Fort St Angelo- Removal of vegetation

49. Fort St Angelo- Maintenance

50. Fort St Angelo, Kannur

51. Fort St Angelo, Kannur

52. Fort St Angelo, Kannur

53. After
Fort St Angelo, Kannur

54. Fort St Angelo, Kannur

55. Fort St Angelo, Kannur

56. Fort St Angelo, Kannur

57. Fort St Angelo, Kannur

58. Fort St Angelo, Kannur
Weathering of Laterite due to aggressive sea environment

59. Temples of Malabar
Trikkaikunnu Temple,
Kottayam
Siva Temple at Ferooke, Calicut

60. Siva Temple at Calicut
Wide Projecting Eaves
Granite Door Frames
Granite Plinth Protection
Traditional Conservation Practices

61. Traditional residences in Malabar, Kerala

62. Traditional residences in Malabar,
Kerala

63. Ancillary structures –temple entrance

64. Ancillary structures –temple entrance

65. Traditional ancillary structures
Bathing ponds attached to temples and residences
Temple enclosure wall-(elephant form)

66. World heritage monuments: Churches and
convents of Goa
Church of St. Francis of Asissi, Goa

67. DETERIORATION TO LATERITE:
BASILICA OF BOM JESUS , GOA

68. Mosque , Goa

69. Traditional Bungalow, Goa
Bungalows in Goa

70. CONSTRUCTION
OF LATERITE
BUILDINGS

76. Foundation

77. PLINTH

83. PREPERATION OF SPECIMEN

84. Engineering properties: compressive strength

85. Engineering Properties
Density Dry 1.80- 2.78
Saturated 2.36-3.04
Specific gravity - 2.84-3.58
Porosity % 20-40
Water absorption % 10- 18
Compressive strength
( MPa)
Parallel to bedding plane Wet 1.29-4.45
Dry 6.0-9.60
Parallel to bedding plane Wet 1.29- 4.54
Dry 4.41- 8.29
Modulus of Elasticity
(Flexure) MPa
Wet 2.09-4.66
Dry 4.41-5.96

86. Weathering Studies
• Field studies- classification of weathering forms
• Laboratory weathering studies
– Slake durability
– Salt crystallisation
– Wetting and drying
• Natural weathering trials
• Weathering process

87. Field Study: Classification of weathering
forms
1
4
2
5 6
3
Granular
disintegration Biodegradation Vegetation growth
Human
intervention
EfflorescenceSalt attack

88. Laboratory weathering studies
Salt crystallisation test (RILEM test No: IV)
Wetting and drying test (ASTM D 5313)
Slake durability test (ASTM D 4644)

89. Laboratory studies
Salt crystallisation testSlake durability test

90. Salt weathering Mechanism – Schematic model
Phase 1
Leaching
Phase 2
Salt crystallisation
Phase 3
Debonding
Vesicules
Clay filled
cavities Salt
crystals
Fragments of
debonded laterite
Honeycomb
•Field weathering forms matched with the laboratory
findings
•Salt crystallisation attack was severe form of decay in
laterite
•Salt and moisture were the mechanisms of salt attack

91. Summary
• Salt attack and biodegradation were the main cause for
weathering in laterite (as determined from the field
studies on monuments)
• Salt crystallisation test proved that dampness and salt
were the agents for the decay mechanism
• Slake durability study established the corrosive action of
acidic rains on laterite
• Strong laterite (high compressive strength) offered good
resistance to weathering (salt attack and rainwater
slaking)

92. Conclusions
• Laterite is sensitive to attack by salt crystallisation; salts migrate into
the structure mainly from the ground
• Deferential weathering of laterite in the same environment suggests
need for protection of weak laterite in damp environment
• Laterite with dense iron formation are found more durable and can
be used in exposed conditions
• Decline in strength of laterite due to saturation suggests protection
from dampness
• Protection from dampness can prevent deterioration to a large
extent

93. THANK YOU