Hazards related to coir pith:

Normally, coir pith is dumped as agricultural waste and become

accumulated as a waste product in the form of heaps of coarse and

fine dusts.

It is estimated that at present there is an accumulated stock of 10 X

106 metric tons of coir pith in the southern states of India viz. Kerala,

Tamil Nadu, Andhra Pradesh, Karnataka, and Orissa.

Coir pith has been traditionally been disposed off by burning. This

burning has resulted in various environmental problems, including

carbon deposits and the warming of the atmosphere.

During the rainy season, the tannins and phenols of the coir pith are

leached out into the soil and into the irrigation canals, thereby making

agricultural lands unproductive. Also, the water pollution caused by

such leaching is harmful to the aquatic and soil biological life.

Coir pith is a biomass residue generated during the extraction of

coir fibre from coconut husk and is a by-product of the coir

manufacturing industry.

The Coconut husk contains 20% to 30% fibre of 60 to 300mm

length. After grinding the husk, the long fibres are removed and used for

various industrial purposes, such as rope and mat making. The

remaining 70% material is composed of short and medium-length fibres

as well as pith tissue, this is commonly referred to as waste-grade coir.

The waste grade coir may be screened to remove part or all of the fibre,

and the remaining product is referred to as coir pith.

Introduction:

Thermal insulation on roofs Heat exchange between a building and its surroundings occurs

primarily through the ‘skin’ of the building e.g. roof, walls, fenestrations

etc.

Roofs and ceiling may amount to about 15 to 50% of the total

heat gain depending upon the roof area and height of the building.

Hence insulation in roofing play an important role in contributing to the

energy loads of a building for achieving thermal comfort through air

conditioning or other strategies.

Improper thermal insulation on roofs may lead to excessive

expenditure on air conditioning and also add to the global energy

consumption when observed on a global scale.

Many agencies have prescribed standards for the thermal

conductance/resistance of roofing assemblies. ECBC prescribes such

values depending upon the region, climate and usage of buildings.

There are many technologies that provide such insulation. But

the production of constituent materials of many such assemblies is

from non-renewable sources and they generally also have a larger

carbon foot print

Most commonly constructed insulation and

water proofing system in India, Brick Bat Coba

(BBC): Roof slabs constructed by RCC need insulation for thermal

comfort and waterproofing treatment to prevent leakage of water. Both

these requirements are supposed to be fulfilled by BBC assembly.

Drawbacks of brick bat Coba:

The drawbacks of brick-bat coba are as follows:

• Provides insufficient thermal insulation

• It imposes unnecessary load on the parent slab

• Damages the parent slab during repairs as bricks adhere to the

parent slab

• If rain water reaches the bricks through cracks, the bricks absorb

the water. But they dry slowly, hence a reservoir of water is created

inside, specially in regions of heavy rainfall

• Needs excellent workmanship

Aims and objectives: Aim: Incorporating coir pith for efficient thermal insulation and

water proofing on terrace RCC slabs.

Objectives:

• To study the applicability of coir pith in a thermal insulation and

water proofing assembly.

• To compare the thermal performance of commonly used system

i.e. brick-bat coba with thermal insulation and water proofing

assembly using coir pith.

• To study the water proofing performance of a thermal insulation

and water proofing assembly of coir pith.

Design of the study Brick-bat coba is the most commonly used system for thermal

insulation and water proofing in India. There are many disadvantages

in using brick-bat coba as a thermal insulation and water proofing

system on terrace RCC slabs as mentioned. Coir pith shows

potentially better thermal insulating and water absorbing properties

than burnt clay bricks and can be a potential replacement for bricks in

conventional brick-bat coba technology.

A comparative study of thermal and water-proofing performance of

Brick-bat coba (BBC) and a system cast by replacing bricks by coir

pith blocks in brick bat coba (Coir Pith Block Assembly, CPBA) is

carried out..

Limitations: • The research needed a detailed study about the thermal properties

of coir pith. No such studies are available, and the laboratory testing

of coir pith for its thermal properties was not possible due to the local

unavailability of apparatus or a laboratory that could perform such

tests.

• There could be many different ways to use coir pith in thermal

insulation and water proofing systems. But due to the limitations of

the time for this study, the assembly casted by replacing bricks by

coir pith blocks in brick bat coba was adopted.

• It was not possible to calculate the exact thermal

conductance/resistance of the two assemblies, that are compared,

due to the time and availability constrains of apparatus and local

laboratories.

• The experiment is conducted on specimen size of 300x300mm, due

to which the implications of the use of coir pit on larger scale cannot

be conclusively found out.

• Due to limitations of time, the specimens could not be tested in very

harsh weather of summer or intense rains.

• This use of this technology is restricted to south Indian coastal

regions due cost implications

• Coir pith blocks loosen up in the presence of excessive water. This

problem was not explored to detail and remains a limitation of the

product.

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Comparative study of thermal performance of CPBA as compared

to Brick-bat coba

Analysis and discussion of resultant data

Conclusion

• Durability

• Load bearing capacity

• Water absorption capacity

• Chemical reactivity

• Fungal and bacterial infections

• Theoretical comparison of thermal performance

• Experimental comparison of thermal performance

• Thermal insulation

Experimental study of water proofing performance

• Designing controlled space

for experiment

• Selecting instruments

and sampling method

• Performing experiment

• Data collection

Applicability of coir pith in thermal insulation and water proofing

system

• Casting of specimen

assemblies

•

• Performing the

experiment

• Observations

Durability

Coir Pith contains three major constituents .

• Cellulose: A polymeric chain of anhydrous glucose units, which

exists mostly in crystalline form

• Hemi Cellulose: Which is made up of mixed polymers of various

pentose and hexose sugars and is amorphous in nature.

• Lignin: A complex amorphous ploymer of phenyl propane which

surrounds the cellulose in cell walls. Lignin is relatively inert to

hydrolysis.

Chemical composition of raw coir pith is listed below: Contents

%(w/w)

Cellulose……………………….35

Lignin…….……………………25.20

Ash…………….………………8.70

Moisture………….…………..11.90

Pentosans………….………….7.45

Fats and Resins…...…………..1.80

Other Materials….…………...10.06

Fixed Carbon………………….37.10

Coir Pith contains Lignin and cellulose in almost equal quantities

around 25 to 35% .

Highly lignified materials are extremely durable and do not

degrade under normal atmospheric conditions. Coir Pith contains lignin

in the same percentage as teak i.e. 30% lignin, Hence it is extremely

durable like teak wood and does not degrade even in the presence of

moisture or water.

Applicability of coir pith in thermal insulation and water

proofing system:

Thermal Insulation

Both Coir and Coir pith have similar chemical composition with slightly

different physical appearance and properties. Coir Pith is more porous and has

more water absorption capacity than coir. Following is the comparison of

porosity and density of coir and coir pith:

Coir Coir pith

Porosity(%) 40 76.77

Density (g/cc) 1.44 0.1525

Coir has Thermal conductivity 0.075 W/mK . Considering the above factors

where the porosity of coir pith is more porous and density of coir pith is less

than coir, it can be concluded that the thermal conductivity of coir pith would be

more and never less than coir. As there is data available on thermal

conductivity of coir pith, for the purpose of this study we consider that the

Thermal conductivity of coir pith as equal to that of coir i.e. 0.075W/mK

Load bearing capacity

For the purpose of our study we would be using coir pith blocks which

are manufactured by compressing coir pith. As there are no available

studies related to the compressive strength of the coir blocks, a

laboratory testing was conducted to evaluate the compressive strength of the coir blocks.

0.000

5.000

10.000

15.000

20.000

25.000

30.000

35.000

0.0 10.0 20.0 30.0 40.0 50.0

Results: Load of failure (kN): 29.1 Stress (Mpa): 0.84

29.1kn=2967.37kg force ~ 3000kg force

Considering the applicability of coir pith blocks on the terrace,

there will be an absence of walls and other dead load and dynamic point

loads, 3000kg force is satisfactory and applicable for terrace thermal

insulation and water proofing system.

Water absorption capacity

In the absence of any study related to absorption capacity of coir pith

blocks, water absorption capacity of coir pith block was experimentally

compared to the water absorbing capacity of burnt cay brick

Design of study

Specimens of burnt clay brick bat and coir pith block having equal

volume were selected. Coir block as wrapped in porous membrane to

avoid loosening These specimens were placed in plastic troughs of equal

size each. The weight of the two specimens and the plastic troughs was

recorded. The experiment was carried out in a controlled atmosphere of

humidity controlled room.

Observations: It is clearly observed that coir pith block had absorbed

962gm and brick had absorbed 234gm of water for the same volume of

specimen size.

Hence, coir pith is a better absorbent of water than Brick. This property of

Coir pith block will be helpful in absorbing any water that percolates into

the system and shall obstruct the water from reaching the parent slab

INCORPORATING COIR-PITH FOR EFFICIENT THERMAL INSULATION AND WATER PROOFING IN ROOF RCC SLAB 2013-2014

Chemical reactivity of coir pith with water

When lignin comes in contact with water for long durations of

more than 6months some of the lignin and phenols are washed away

into the water to the extent of 5 to15%. But studies have shown that

there is no further loss of constituents or mass of coir pith even after

coir pith is in contact with water for further prolonged periods. Studies

conducted on 15 year old hillocks of coir pith have shown that there

has been 5 to 10% loss of lignin and same amount of loss of phenols

with negligible change in other constituents. Lignin forms the outer

lining of cellulosic material and protects it from disintegration. The

physical properties of coir pith unaltered.

The inert behaviour of coir pith towards water proves it as an

applicable material in the water proofing system.

Fungal and bacterial infections

Coir pith is not infected by commonly present bacteria or fungi.

Due to this it requires a highly complicated procedure where controlled

atmospheric conditions and rare bacteria are required to disintegrate

coir pith into compost which can be used for agriculture.

Due to the absence of potential infections due to fungi and

bacteria, coir pith is extensively exported to gulf and European

countries as a growing medium for horticulture without the risk of

exporting indigenous specious of fungi and bacteria to foreign

countries.

As coir pith does not bare a risk of getting infected by fungi

and bacteria unless under controlled circumstance in the presence of

rare bacteria and fungi, it can be effectively used as part of thermal

insulation and water proofing assembly in the construction industry.

Theoretical comparison of thermal performance: Thermal insulation and water proofing system with

Brick Bat Coba (BBC): .

The achieved resistance of the assembly is 0.351m2k/w which is very

low as compared to the minimum required 2.1 m2k/w by ECBC

Standard for all climates for day use buildings in India.

Dead load on parent slab calculation:

The total dead load exerted by brick-bat coba on parent slab is 4.2kN/

m3

Thermal Insulation and water proofing cast by replacing bricks

by coir pith blocks in the brick bat coba (CPBA):.

The achieved resistance of the assembly is 2.321m2k/w which

complies with the minimum required 2.1 m2k/w by ECBC Standard for all

climates for day time use buildings in India.

Dead load on parent slab calculation:

The total dead load exerted by coir pith system on parent slab is

1.365kN/m3

Table of comparison:

Sr.No

. Design Details

Resistance

– m2k/w

Dead load

kN/m3

A Brick Bat Coba 0.351 4.2

B CPBA 2.321 1.365

Experimental comparison of thermal performance

Casting of specimen

assemblies

Designing controlled space for experiment

Selecting instruments and sampling method

Performing the experiment

Data collection

INCORPORATING COIR-PITH FOR EFFICIENT THERMAL INSULATION AND WATER PROOFING IN ROOF RCC SLAB

Designing controlled space for experiment The study of thermal performance of the two specimens involves

recording the temperatures of the top and bottom of the assemblies. The

top surface has to be exposed to the sky and the respective solar radiation.

The bottom of the slab needs to be insulated from the direct solar radiation.

In order to protect the bottom of the slab from direct exposure to the solar

radiation and to achieve identical environments at the bottom of the slab a

small enclosure of size 300x300mm is created using polystyrene sheets as

insulation.

Experiment enclosure for BBC Experiment enclosure for CPBA

Performing experiment

• The two assemblies on the stands with the enclosed room at the bottom

of each are placed on the terrace such that no shadows of the over-head

water tank fall on them.

• 4 temperature sensing probes are attached to the surface of the top and

bottom of the two assemblies respectively.

• The probes are connected by wires to the microtronics temperature data

logger.

• The data logger is set to record temperatures at intervals of 20mins

• The experimental setup is let undisturbed for 5 consecutive days.

• After 5 days, the data logger is disconnected from the temperature

probes and connected to a computer having Microtronics Soft software.

• The data is downloaded from the data logger to the computer.

Data Collection:

The top and bottom temperatures of the 2 assemblies are plot on a

graph for each day and data of three days is selected for analysis.

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CPB slab bottom

Day 1: 07-08-2014

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BBBC slab top

BBC slabbottom

CPB slab top

CPB slabbottom

Day 2: 08-08-2014

Day 2: 09-08-2014

Observations and analysis:

After conducting the experiment and observing the graphs of the thermal

performance of BBC and CPBA the following points are found:

• By the use of coir pith better thermal insulation was achieved.

• The parent RCC slab bottom of CPBA got heated only up to the ambient

air temperature. Heat did not get transferred through the CPBA to the

bottom of the parent RCC slab. Whereas the RCC slab bottom for BBC

showed temperatures higher than the ambient temperature, proving that

some amount of heat got transferred through the BBC to the parent RCC

slab.

• The slab top of CPBA got heated quickly and also cooled down quickly.

CPBA top got heated more than BBC as there was no heat dissipation

through coir pith blocks. It also cooled down quicker than BBC as only

the 25mm thick screed retained heat and hence the thermal mass was

low. CPBC acted as a thermal barrier or insulator.

• In BBC heat dissipated through the screed to the bricks and to the

parent slab. This whole assembly acted as a thermal mass. Hence BBC

took more time to cool down or heat up.

Experimental study of water proofing

performance In order to actually test the water proofing performance of an

assembly in natural weather conditions it would take years. So in

order to expedite the process and limited time span of the study a

simpler and quicker method was devised.

In actual scenario, wear and tear of the water proofing

assembly as well as the parent RCC slab takes place due to

expansion and contraction and varying loads. Water leakage starts

when water enters the water proofing assembly from cracks on its

surface and reaches the parent slab and seeps to the bottom of the

slab. When the water reaches the RCC slab, it means that the water

proofing assembly has failed. So it means that a water proofing

assembly is successful if the water is stopped from reaching the

parent slab.

Performing the experiment

The screed on the surface of the CPBA was cracked with the

help of a hammer.

The assembly was left exposed to the monsoon rains from 12th June

to 20th June.

Observations were made after separating the CPBA assembly from

the Parent RCC slab

Observations • The surface of the RCC parent slab was dry.

• All the water that seeped through the cracks on the surface was

absorbed by the coir pith block.

• While separating the CPBA from the parent slab, no damage was

done to the slab, which is persistent to BBC as bricks adhere to

the slab.

• The water proofing compound layer was not damaged.

Summery and Conclusion The introduction and use of RCC technology for constructing

buildings in India has increased the pace and reliability of Indian

construction Industries. But due to the inefficient thermal insulation

and water proofing capabilities of concrete, technologies like brick

bat coba have to be used for terrace level slabs. Brick bat coba is

used abundantly because other technologies are unavailable in

most parts of India and casting brick bat coba is much cheaper.

But brickbat coba in itself is inefficient in thermal insulation

and water proofing due to the extreme climatic conditions in most

parts of India. This leads to the cooling energy loads in the

buildings. Hence there is a lack of energy efficiency leading to

national and global energy crises. Also there are frequent water

leakage problems in roof slabs due to inefficiency of brick bat coba.

From the study done in this research it was found that coir

pith is applicable as a material in thermal insulation and water

proofing assembly. CPBA is a much more efficient thermal

insulation and water proofing system than brick bat coba.

Incorporation of coir pith in the thermal insulation and water

proofing assembly would help in insulating the parent slab from the

heat of the sun, hence reducing the heat transfer to the interior

spaces. There will be lower consumption of energy required for air

conditioning the interior spaces, achieving energy efficiency. Also,

CPBA acted as an efficient water proofing system.

Coir pith absorbed almost all the water that percolated into

the assembly and did not allow it to reach the parent slab, which

proved that coir pith can be efficiently used for water proofing.

Coir pith is a by-product of coir industry and is proving to

be a soil pollutant due to excessive dumping and air pollutant due to

burning of coir pith for its disposal. Through further research, if a

consolidated technology is developed and more uses for coir pith

are explored in construction industry, it would prove to be a boon for

the nature and also a money spinner.

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BBC slab top

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CPB slab top

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2013-2014