Stabilization of Soils by Termites
Transcript of Stabilization of Soils by Termites
Natural Stabilization of Soils With Special Reference to
Entomological Considerations
by
Dr.A.S.Nene and Y.D. Parihar
Termites, Wasps and earthworms can be considered
as soil engineers because of their effects on soil
properties.
Insects or Soil Engineers
v In nature there are insects that stabilize and
use soil for their dwellings. Such insects are
Wasps, Earthworms and Termites etc.
v The stabilization agents used by these insects are
yet unknown.
v Many ancient Indian Texts on Engineering mention
the use of ant-hill soils for mud plaster, mud flooring,
metallurgical crucibles and clay idols.
Introduction
Fascinating Facts about Termites and Termitarium (Ant-hills)
Ø Termites use adjacent soil grains for construction of
ant-hill.
Ø These particles are coated with sticky rapidly
hardening material secretions from mouth or rectum.
Ø On drying the material becomes hard as rock.
Ø Strength of the ant-hill increases with time.
Ø Ant-Hills are very strong and need sharp tools, or evendynamites to destroy.
Queen’s Chamber
Ø Size and shapes of termitarium are indicative of the species of termites.
Ø Shapes may like a mushroom,column, pyramid sheet piles etc.
Ø Size may be as large as 4 m. at base and height up to 9 m.
Ø On a scale of relative size, a man made pyramid would be4 km high !
Ø In spite of the huge soil mass used for giant ant-hills, there is no cavity in the ground.
Research Objectives
§ To study the engineering properties of ant-hill soiland compare with the properties of parent soil fromwhich the ant-hill are constructed.
§ To Conduct Chemical analysis of ant-hill soil for pH, phosphates and sulphate content.
§ To Conduct X ray Diffraction tests.
§ To Identify the secret of construction of ant-hills which will be very useful for low cost mud constructions.
The secret of construction of ant-hills
Cellulose54.6%
Pentosans18.0%
Lignin27.4%
Cellulose18.0%
Pentosans6.5%
Lignin75.5%
Food
Before Digestion After Digestion
1. Field visits and Samples collection
• Samples were collected from seven sites of Vidarbha.
• For each site two samples were collected.
• The first sample was of parent soil and the second sample was from ant-hill.
• About 10 kg soil samples were collected from each site for laboratory testing.
2. Laboratory Investigations Part 1
Following laboratory tests were conducted on 14 samples collected from seven sites.
Ø Differential free swell test (DFS )
Ø Grain Size Analysis (GSA)
Ø Consistency Limits (Liquid Limit -LL, Plastic Limit -PL and Shrinkage Limit -SL
S1 S2 S3 S4 S5 S6 S7
Site No
0
5
10
15
20
25
30
35
DF
S V
alue
%
Parent Anthill
Reduction in DFS Value and Nominal reduction in Liquid Limit
S1 S2 S3 S4 S5 S6 S7
Site No
30
35
40
45
50
55
60
65
Liqu
id L
imit
%
Parent Anthill
S1 S2 S3 S4 S5 S6 S7
Site No
10
12.5
15
17.5
20
22.5
25
27.5
Pla
stic
Lim
it %
Parent Anthill
Increase in Plastic Limit and Shrinkage Limit
S1 S2 S3 S4 S5 S6 S7
Site No
0
2.5
5
7.5
10
12.5
15
17.5
20
22.5
25
27.5
Shr
inka
ge L
imit
%
Parent Anthill
S1 S2 S3 S4 S5 S6 S7
Site No
0
10
20
30
40
50
60
Sw
ellin
g P
ress
ure
kP
a
Parent Anthill
Reduction in Swelling Pressure
Ø Swelling Pressure test (Constant volume method)
Ø Chemical Test on soils for pH
Ø Sulphate and Phosphate content test
Ø X Ray Diffraction test.
Laboratory Investigations Part 2
Laboratory tests were conducted on parent soils from three sites to find
Ø The effect of lignin on Consistency Limits of soils.
Ø The effect of lignin on dry density- Optimum moisturecontent of soils
CHandur Rajura Nagzira0
10
20
30
40
50
60
Liqu
id L
imit
%
0% 4 8 12
Effect of Lignin on Liquid LimitCHandur Rajura Nagzira
10
14
18
22
26
Pla
stic
Lim
it %
0% 4 8 12
Effect of Lignin on Plastic Limit
Decrease in Liquid Limit but increase in Plastic Limit
CHandur Rajura Nagzira12
16
20
24
Shr
inka
ge L
imit
%
0% 4 8 12
Effect of Lignin on Shrinkage Limit
Increase in Shrinkage Limit
Conclusions
Based on the review of literature and limited laboratory
investigations following conclusions were drawn.
vThe swelling characteristics of parent soils are drastically reduced in Natural stabilization by termites.
vThere is negligible change in soil Constituents of soil.
vLignin of the cementing material is the secret of strength of ant-hills.
vMore research is necessary to create similar cementing agent on large scale.
References
1. Eugene Marais (1973) “Sole of white ants”, Penguin Publications, London.
2. Roonwal M.L. (1979) Termite Life and Termite control. Scientific Publishers Jodhpur.
Ø Nene, A.S. and Parihar, Y.D. (1992)"Natural Stabilizationof Expansive Soil" Proceeding of Indian GeotechnicalConference 1992, Calcutta, 18-20 December 1992, Vol.1 .pp 207-209.
Ø Nene, A.S. and Parihar, Y.D. (1996) “Natural Stabilizationof soils with special reference to Entomological considerations" Second International Conf. On Soft soilEngineering, Nanjing (China) May 17-20.
Publications