Pradhan Mantri Awas Yojana - Gramin (PMAY-G) · Author: ILOVEPDF.COM Created Date: 9/7/2015...

No. M-1301 l/05/2013_RHGovemment of India

Ministry of Rural Development(Rural Housing Division)

Krishi Bhawan, New Delhi,Dated: 3rd September, 2015

To

The Principal Secretary / Secretary (Rural Development)ofall State Govemments and UT Administrationdealing with lndira Auaas Yojana.

Subject: Production of Fly Ash atrd Cemeot Stabilized Earth Blocks for utilising in theconstruction ofIAY House - Detailed Project Report - Regarding,

Sir / Madam

I am directed to refer to the discussions held during the Regional Review Meetingsheld on 18th, 20th and 25th August, 2015 wherein a presentation was made by NIR&PR on theproduction offly ash and cement stabilized mud blocks. Based on the interest shown by the StateGovemment in the proposal, it was decided that a Detailed Project Report (DPR) prepared byNIRD&PR would be circulated among the states for comments and suggestions.

In this connection, I am forwarding herewith the DPRS on Fly Ash and CementStablized Mud Blocks (CSEB) for your perusal. You are requested to examine the DPRS and

firmish your comments and suggestions with reference to the feasibility ofproducing and usage

of the bricks, projected requirement, source of funds to meet the expenditure for producing thebricks, system of supplying the bricks to the beneficiaries of [AY, acccptability ofthe people touse the bricks, etc. by 30th September, 2015.

Based on the inputs and expression ofinterest received from the States, the modalitiesofproduction ofthese bricks and supply ofthe same to the beneficiaries of Indira Awaas Yojanacan be worked out. Further, an odentation and training workshop for the States / UTs on theproduction ofthese bricks would be organised at NIRD&PR.

Yours faithfully

Encl: l. DPR on Fly Ash Bricks

2. DPR on Cement Stablized Eanh Blocks nWPL-(M. Rama Krishna)

Undcr Secretary to Govt. of IndiaTel:233813.13

INSWAREB Visakhapatnam

Report on

Production of FaL-G Bricks and Blocks

For

NATIONAL INSTITUTE OF RURAL DEVELOPMENT & PANCHAYAT RAJ Hyderabad

(Strictly Confidential-Not for circulation)

Consultants:

Institute for Solid Waste Research & Ecological Balance (INSWAREB)

FaL-G Mansion 32-10-53. Shri Venkateswara Colony

Visakhapatnam 530012 Phone: +91-891-2516411

Fax: +91-891-2517429 e-mail: [email protected]

August 2015


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Contents

Page No.

Background … … … … … … 3

Understanding Fly ash ... … … … 3

FaL-G Technology … … … … … 6

Project at a Glance … … … … … 13

Schematic Process Flow Chart for FaL-G bricks/blocks 14

Specification of fly ash bricks … … … … 15


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BACKGROUND

There are two formidable avenues of utilization for fly ash; one in production of bricks &

blocks, and the other for the production of cement and concrete. In either case, the role

of fly ash is pozzolan. In the case of brick & blocks, fly ash is tapped of its pozzolanic

virtues in association with lime and/or cement, getting converted as cementitious binder

which attains strength through hydration chemistry. Earlier to the advent of FaL-G

technology, the known practice was to compress the mass in heavy duty press followed

by autoclaving at high temperature (about 180 oC) and pressure (around 12 atm). These

process steps made the plant costly prohibiting micro and small scale entrepreneurs to

practice the technology. Just by tapping the aluminate phase of fly ash into a strength

rendering mineralogy ie., as calcium alumino-sulphate hydrates, FaL-G could boost of the

strength of fly ash-lime by three to four fold, eliminating the dependence on press and

autoclave. Thus the plant cost has slashed down from a few crores to a few lakhs, almost

to 1/100th of erstwhile plant, bringing the technology within the reach of micro and small

entrepreneur. This has helped the proliferation of over 18,000 plants throughout the

country as on date, generating over 54 billion bricks annually putting almost 27 to 54

million tons of fly ash to use only in brick segment.

UNDERSTANDING FLY ASH

Fly ash is the incombustible residue of clayish material entrapped in coal during its

formation and emerges as byproduct in coal combusted thermal power plants. While the

basic quality of fly ash depends on the nature of clay in the coal that differs from source

to source, the other qualities such as fineness, reactive phases depend on coal mill,

combustion conditions of boilers, and collection mechanism.

Ever since fly ash has been identified as a pozzolanic material, to offer better

performance towards long-term durability of concrete, studies have been simultaneously

initiated to establish correlations between the characteristics of fly ash and its

performance in concrete.

Fly ash characteristics are significantly distinct when compared to other pozzolanic and

cementitious materials due to which it is accredited to offer ‘Holistic Performance’ when

used in concrete. Till mid of 80s the Indian fly ash quality had been considered to be poor

in comparison to that of fly ashes at global level. The thrust given for energy efficiency of


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coal combustion and environmental regulations on stack emissions, however, resulted in

an unasked for benefit to improve the quality of fly ash. Thus present quality of Indian fly

ashes is considered adequate and nowhere inferior to international standards. In this

background thrust is given in India also to characterize the fly ashes.

In modern thermal plant operations, coal is segregated of its impurities and clayish lumps

and ground to a fineness of about 75 micron (70% passed). This coal powder is injected

into combustion chamber where the coal particles burn instantaneously within the least

residential time. After combustibles are burnt the residual particles get converted into

ash particles that tend to fly out along with flue gases, living up to its name as ‘fly ash’.

The flues are subjected to economiser, in order to recover the heat of air and ash, in the

process of which the ash particles are subjected to sudden fall in temperature generally

known as quenching, that, in turn, improves reactivity to fly ash.

The fly ash is separated out of flue gases and entrapped in electrostatic precipitator (ESP)

or bag filter. The ESP normally consists of four to six fields (hoppers). The field at boiler

end is the first field and the one at stack (chimney) end is the last field.

American Society for Testing and Materials (ASTM) classified the fly ash based on the coal

type. Generally coal is available in four types viz., Anthracite, Bituminous, Sub bituminous

and Lignite. In addition to various clay mineralogies the latter two coals contain alkali and

alkaline earth based mineralogical phases. When these coals undergo combustion the fly

ash is generated with calcium and alkali associated mineralogy. Thus the basic difference

between first two types and latter two types lies in the calcium oxide (CaO) content.

Hence ASTM used CaO as the dividing parameter for classifying fly ash into two

categories.

ASTM Class C Fly ash:

The fly ash generated through the combustion of lignite and sub bituminous coal, and

that contains CaO higher than 10%, is Class C. The presence of reactive calcium

associated mineralogy such as dicalcium silicate and tetracalcium sulphoaluminate,

makes these fly ashes self-hardening. Means class C fly ashes exhibit both cementitious

and pozzolanic characteristics. The presence of reactive phases makes Class C fly ashes

less resistant for chemical attacks and relatively prone for distress of concrete as

observed by many researchers.

ASTM Class F Fly ash:


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The ash generated through combustion of anthracite and bituminous coal, and that

contains CaO lower than 10%, is Class F. These fly ashes generally contain too low CaO to

develop considerable quantities of calcium-associated mineralogy. Hence Class F ashes

are less reactive or dormant in comparison to Class C and exhibit only pozzolanic

characteristics. The absence of calcium associated reactive phases makes Class F fly ashes

to offer better durability to concrete and enhanced service life for the structures.

In India, almost all the boilers generate Class F fly ash, except a couple of pockets in

South India and extreme West where Class C fly ash is generated. Indian code IS 3812-

2003 gave a nomenclature of siliceous pulverized fuel ash for Class F and Calcareous

pulverized fuel ash for Class C in line with European standards.

With reference to Indian operations, INSWAREB’s classification of fly ash is significant as

follows:

LT fly ash

The fly ash generated out of combustion temperatures of 750-850 oC is classified as Low

Temperature (LT) ash. This is more reactive at early ages of hydration, thus highly

suitable for precast products such as bricks and blocks. The reactive SiO2 and Al2O3 are

available as metakaolinite phases in LT fly ash those render rapid hydration in the

presence of lime, with particular reference to Al2O3. But their high LOI in the range of 4 to

6% forbids their use in cement and concrete.

HT fly ash

The fly ash generated out of combustion temperatures of 900 to 1400 oC is classified as

High Temperature (HT) ash. As explained earlier the constituents of silica and alumina

form as metastable glass phase or spheroids or cenospheres in HT fly ash with relatively

slow reactivity. Till the glass phases get broken and the silica and alumina enter the

matrix, the reactions of HT fly ash are slow manifesting as low reactivity at very early

ages. But once this phenomenon triggers off HT ashes contribute for potential hydration

chemistry and offer better performance at late ages. This feature associated with low

LOI at less than 1.5% makes HT fly ashes more preferable in cement and concrete.


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FaL-G TECHNOLOGY

FaL-G is a pozzolanic binder to tap the potential of fly ash towards cementitious

applications. This means, a well synthesized FaL-G behaves like cement and can be used

for mortar and concrete applications upto certain strength grades.

Originally FaL-G was developed in lime route. The FaL-G mix at 60:30:10 is synthesized,

considering the purity of lime [Ca(OH)2] at min. 85% and calcium sulphate purity at 95%.

These purities need to be aimed at while selecting the raw materials.

The best properties of FaL-G manifest when fly ash + lime + gypsum are ground in a pan

mixer, along with fine aggregate, till the paste gets thoroughly homogenized. Depending

on the mixer efficiency, this takes about 2 to 3 minutes.

In order to enlarge the scope of raw materials, FaL-G is developed later on in cement

route, availing OPC as source of lime. While FaL-G with LT fly ash hardens faster, the

same with HT fly ash takes relatively longer time in association with lime. Hence for early

setting, hardness and strength, it is desirable to deploy OPC for FaL-G made of HT ash.

Such mixing of OPC to fly ash could be 10:90 to 30:70 depending on target strength and

setting behaviour.

All the building elements which are manufactured using OPC can equally be

manufactured based on FaL-G. Particularly for low strength applications, the cement is

minimized making the mortar or concrete permeable. While the same elements are

manufactured using FaL-G, the impermeability is impressively high because of higher

particulate input of fly ash and lime for the given weight. The ultimate strengths depend

on the quality of raw materials, mix preparation and mix design. However, certain

stringent quality control aspects need to be observed to tap the potential of FaL-G.

Fly ash:

Fly ash is available from ESP of the thermal plants. While it is acceptable to use

composite fly ash from all the fields of ESP, it is desirable to collect fly ash from the

second field onwards for better reactivity. Three parameters need to be checked to

assess the quality of fly ash as follows:

Blaine Fineness: Not less than 3000 cm2/gm. Or

Retention on 45µ sieve: Not more than 34%


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Pozzolanic activity Index: Not less than 80% of the control mortar. (vide ASTM C311)

Lime:

Lime is available as byproduct in acetylene industry in the form of Ca(OH)2. It is always

necessary to use lime in the form of calcium hydroxide Ca(OH)2 otherwise called as

slaked lime. The wet sludge should never be allowed to dry up, lest the same gets

carbonized, proving of no use for cementitious reactions. The slaked lime should be

analysed of its purity in terms of Ca(OH)2 through sucrose test, and the purity should not

be less than 75%. It is desirable to maintain CaCO3 as low as possible if not totally

avoided in the lime.

If at all quick lime (CaO) needs to be used, the same should be slaked for three to four

days and the resultant paste has to be used. The heat of hydration of quick lime is

harmful and causes cracking for the product. Pebbles and unreacted lime stone need to

be segregated and thrown out while using the slaked lime.

Determining quality of Lime:

Purity of lime is generally mentioned in terms of CaO. When lime stone is sintered to

produce quick lime, certain portion remains invariably as unburnt lime (CaCO3) and its

portion of CaO is of no use for reactions. Hence while accepting quick lime (CaO) or

slaked lime [Ca(OH)2], it is desirable to have the purity of product in terms of calcium

hydroxide. Here are some workings for a notional sample of lime which has 70% as burnt

lime; 20% as unburnt lime and 10% other constituents:

Constituent content As CaO Constituent As Ca(OH)2

Burnt lime 70% 70 Burnt lime 92.4

Unburnt lime 20% 11.2 Unburnt lime 00

Total CaO 81.2 Total Ca(OH)2 92.4

As CaO 70

Procedure for determining Ca(OH)2:

The following is the approach to determine the purity of Ca(OH)2 in calcined/ quick lime

and hydrated lime, available either from mineral source or as a byproduct from acetylene

industry or any other such source.

1. Weigh 1 gm of sample and put in 500 ml volumetric flask.


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2. Add 30 gms of Sucrose to the sample.

3. Add 300 ml of distilled water into the flask and shake well for 1.5 hours for

effective reaction.

4. Make upto 500 ml. and shake well for about 5 to 10 minutes.

5. Take 50 ml aliquot from main solution and titrate against 0.1 N HCl in the

presence of methyl orange as indicator.

Calculate Ca(OH)2 as follows: % Ca(OH)2 = Titer value x 100 x 0.003705/sample weight.

Gypsum:

Anhydrite gypsum offers best results to render early strengths for fly ash-lime mixture.

This is available as byproduct in the aluminium fluoride industries such as TANFAC,

Cuddalore. It is desirable to use anhydrite gypsum with a purity of not less than 95% in

terms of CaSO4, after grinding to a Blaine fineness of not less than 3200 cm2/gm, for

better dispersion and early participation in hydration chemistry.

Plaster of Paris (PoP) available from Rajasthan can also be used but the mix derived

should not be allowed to stack for longer time (beyond 30 minutes).

Last choice is to use dihydrate gypsum available from fertilizer industry as byproduct of

phosacid production and popularly known as phosphogypsum. Since this grade of

gypsum does not contain heat of hydration, it contributes slowly to FaL-G chemistry as

against above two grades of gypsum. However when phosphogypsum is used it needs to

be washed off the salts and chemical impurities those percolate during the phosacid

process.

Tests on Fly ash:

To ascertain suitability as pozzolanic material, Consultants do study fly ash for three

physical parameters vide IS:1727, IS:3812, ASTM C311 and C618. The studies on typical

fly ash from NTPC, Simhadri, have given following parameters:


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Study Reference

code

specification Result on

NTPC fly ash

Loss on Ignition IS 1727 & 3812 Max 5% 0.30

Retention on 45µ IS 1727 & 3812 Max 34% 28.2

Pozzolanic Activity Index (PAI):

This is more a performance oriented study to ascertain the quality of fly ash in

association with OPC. As a matter of fact, this study alone can judge the quality of fly ash

for putting to use without hesitation. All remaining studies do prove as corroborative

studies. Strength of OPC (80%) + fly ash (20%) mortar is compared against that of OPC

(100%) mortar which should not be less than 0.80. This means, if the PAI is 0.80, addition

of fly ash has not diluted OPC strength and thus it is acceptable. If the PAI is 0.80 to 1.0,

fly ash is contributing its part of strength and such quality is desirable. If the PAI is above

1.0, fly ash is behaving better than OPC, while associated with OPC, and such fly ash

should be procured even at higher cost than OPC due to its contribution to durability in

addition to strength.

PAI studies are more conservative through ASTM C311 and C618 as against the same

studies vide IS: 3812. ASTM prescribes 80:20 weight ratio for OPC to fly ash where is IS

code advocates correction based on specific gravity (SG). Since SG of fly ash is relatively

lower than OPC, it results in putting more OPC and lesser fly ash, creating room for

higher strength as fly ash blend. Hence for the purpose of understanding fly ash, PAI vide

ASTM code is more practical. The table below shows improvement in PAI with fineness:

Mortar Compressive strength, MPa PAI-28-day

7-day 28-day

Control mortar 42.4 53.4 --

Mortar with fly ash of

residue % on 45

28.2 36.3 54.0 1.01

38.4 31.6 46.8 0.88

Typical FaL-G Mixes for Commercial Production:

Based on studies of various fly ashes throughout the country, INSWAREB recommends

following mix proportions for LT fly ash in lime route and for HT fly ash in OPC route.


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Constituents LT fly ash in Lime route Inputs in Kg

HT fly ash in Cement route Inputs in Kg

Fly ash 60 76

Lime 30 --

OPC -- 20

Anhydrite gypsum/PoP 10 04

Stone dust/sand 300 300

Total: 400 400

Density, kg per cu.m 2000 2000

Note: In the above mix, 25% of cementitious material gets added for mass balance. This means input of 2000 kg becomes 2125 kg But this gain of 125 kg is not taken into cost computation as conservative approach, and to offset against wastage.

Pan mixer takes 160 kg of input + approx. 12 kg water, per each batch. It takes 3 minutes

for each batch that includes charging of raw material and discharge of mixed product.

Thus the mix output is 27.5 tons per shift of 8 hours that is equivalent to 7200 bricks or

1528 blocks.

Notes for above mix:

1. The above mixes are typical and applicable by and large. However, it is desirable

to study fly ashes in various proportions for optimum strengths so as to arrive to

absolute mix proportions.

2. Quality of fly ash does vary based on combustion conditions and fineness. Hence

it is not guaranteed that all fly ashes at above mixes give same strengths and

engineering properties.

3. Lime with purity of 75% [in terms of Ca(OH)2] is used to arrive to above

proportion. In case of fall in purity, input of lime has to be commensurately

increased.

4. While using HT fly ash in cement route, only OPC should be used but not blended

cements.

5. Water input is not prescribed because it varies based on characteristics of inputs.

The ideal dosage is to be derived till the mix attains thixotropic state, as imparted

in practical training.


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Guidance on Plant & Machinery:

FaL-G is somewhat the ‘Ayurveda’ of cementitious system; which means attainment of

potency is through attrition. The product attains strength through right chemistry rather

than physical compaction. Hence basic requirement of machinery is Pan mixer which is

also called as Roller mixer. Once the FaL-G mix is prepared, even a wooden hand mould,

as used in clay brick casting, is sufficient to cast FaL-G bricks with strength of 8-12 MPa.

FaL-G Brick production using wooden mould as used in clay brick production

Use of various machines for casting is primarily to render better shape and massive

production. Hence there is no need to use high pressure hydraulic machines in the

anxiety of getting better engineering properties. Even a simple vibratory table-casting

system is capable to give a brick of 30 MPa strength, if right mix is used.

Sakar-Vibratory table capable to give strength of 30 MPa (This plant is considered for project workings)


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There are numerous varieties of casting machinery available in India extensively right

from a cost of Rs. 60,000 to Rs. 60.00 Lakhs, giving perfect finish and massive output.

Hydraulic presses of Rs. 20.00 lakhs (15,000/shift) and Rs. 6.00 lakhs (8,000/shift)

How to test good FaL-G Brick/block:

Allow the product to get cured for 21-28 days for major part of hydration. Curing for 14

days is recommended before dispatch so that remaining curing takes place during

construction.

The testing should be done on a 28-day product:

Take the product into hand and rub with thumb vigorously. No powder of fly ash

should get detached from the element.

After 28-day of curing, take the product and dry in air or in oven (at not more

than 50 oC) completely till the product attains constant weight. There upon dip

the product in water for 24 hours or till constant weight. The gain in weight

should not be more than 15%.


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Project at a Glance

Description

Land, civil structures and infrastructure 780,000

Plant and Machinery 599,500

13,79,500

Margin Money for Working Capital 298,941

Total Project cost 16,53,597

Profitability based on 300 working days: 829,037

Project Loan 10,74,838

Promoters’ Contribution 578,759

Total working capital (for 3 months) 886,635

Work force: Administrative & Supervisory: 2

Operational personnel: 17

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Utility Requirement:

Power: Installed capacity: 15 KVa

Raw Materials:

Fly ash from Vijayawada/Ramagundam/Bhupalapalle

OPC from cement factories in truck loads

Anhydrite from TANFAC, Cuddalore or POP in market

Products to be manufactured: Output/day Sale Price

FaL-G bricks of 23*11*7.5 cm 6000 4.50

Alternately FaL-G blocks 30*20*15 cm 1500 16.00

Alternately High Strength FaL-G blocks 31.5*15*15 cm 1200 27.00


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Schematic Process flow chart for FaL-G Bricks/blocks


15

Specification for Fly ash bricks and blocks BIS 12894: 2002


16


17


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Khadanza with High Strength (M-25 grade) FaL-G Blocks: The clay brick of yesteryears has been produced out of very fertile soil with absolute

water repellence and strengths in the order of 150-200 kg/cm2. Earlier to the advent of

OPC into construction arena with its history of 175 years, sintered clay products used to

be the popular structural media. Canal linings and khadanza roads are some popular

infrastructure avenues where the quality of bricks used to be aptly tapped to serve the

technical requirements.

With deterioration in quality of clay, undue

reduction in sintering practices (on account of

spiraling fuel costs) and fall in production standards,

use of brick in infrastructure applications is avoided

dominated by cement-concrete simultaneously.

FaL-G is poised to revive this trend with its superior

technical virtues and modest cost factors. Opening

up such applicational avenue creates market for

hundreds of billions of bricks summoning for

additional production capacities in huge quantities,

notwithstanding its demand in housing sector.

With rapid urbanisation, the need for more and more rigid pavements is gaining

importance. However, monetary constraints of exchequer do not permit the execution

of expensive rigid pavements with concrete. Flexible pavements with bitumen, though

proved to be relatively cheaper to concrete, are observed to be more expensive in long

run on account of vulnerability against rain (water) and recurring cost of their

maintenance. It is in this background, khadanza pavements with FaL-G bricks are going

to offer as viable alternate to the exchequer.

95-year old Khadanza with clay bricks in UP


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The country is going to be flooded with fly ash in view of more and more thermal plants

in the pipeline. Urgent steps need to be taken for regulation and mass scale utilisation of

fly ash. Fly ash generation at 200 million tpa as of now and about 270 million tpa by the

turn of the decade (2020) is a colossal quantity to be taken care in the present day

context of 20-30% utilisation. Brick production is considered as a massive avenue of fly

ash utilisation on account of techno-economic feasibilities of FaL-G technology. It is

more sensible to tap high strengths of FaL-G bricks for infrastructure applications. In this

context, revival of khadanza pavements with FaL-G bricks is not only a viable proposition

to the exchequer for laying durable pavements but also contributes for mass scale fly ash

utilisation which is another factor of equal importance to the country.

To prove it in the field, INSWAREB Building Centre has laid khadanza pavement in 1994

with FaL-G bricks on trial basis at Sheelanagar, Visakhapatnam, an area laden with black

cotton soil. This experimental road was funded by Housing & Urban Development

Corporation (HUDCO) under R&D grant assistance.

Khadanza Pavement laid in Shri Venkateswara Colony, Sheelanagar in 1994 is good state even after 20 years

Another stretch of pavement was executed at the entry of INSWAREB Building Centre,

Paravada in 2009 getting exposed to traffic of incoming and outgoing vehicles that carry

raw materials and finished products of the unit.

1994 2014


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The design of ‘khadanza’ pavements involves the orientation of bricks in

specific manner where the headers make a perpendicular angle with

stretcher which, in turn, makes another right angle with header. The

orientation continues in ascending or descending order till the last brick

reaches the edge of the road.

No mortar joint will have a length more than the total of length and breadth of the

brick. The joints are normally maintained with considerable width, say not less than 15

mm, to facilitate easy penetration of mortar slurry. The mortar slurry is filled through

gravity feed than poking into the gaps. Thereby the mortar settles down in the gaps of

bricks, if any, even at the bottom plane of placement in order to render better rigidity

and absolute filling. Such orientation of joints is considered to make the pavement

crack-free and more rigid. In view of high WCF required for slurrying, mortar is made

of rich mix at 1:3.

Khadanza pavements with FaL-G bricks offer the following advantages :

A. Khadanza work is convenient, as a substitute to concrete pavements, wherever

the concrete mixers and vibrators are unavailable/inaccessible.

Khadanza pavement with FaL-G blocks executed in 2009 at INSWAREB Building Centre,

Paravada Village, Visakhapatnam.


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B. In places like bylanes and slum roads, where entry of road rollers is ruled out for

constructing flexible pavements, khadanza can substitute concrete pavements

easily.

C. Khadanza road can be offered with its optimum strength right from the first day,

as long as fully cured bricks are used, because the bricks do take the loads and

hence these roads can be released for traffic relatively at early age.

D. The roads are crack-free and amenable for localised repair to the extent of

damaged brick area.

E. No expansion joints are required because the expansion stresses are absorbed by

mortar joints.

F. Khadanza pavement is cost effective by 40% over concrete pavement, with

enhanced performance. In addition, cost of steel as dowels, screed bars etc., is

saved further.

G. FaL-G bricks and blocks can be manufactured at village level deploying local labour

creating enormous rural employment. The plant and machinery are very simple at

a cost of Rs. 5.50 lakhs.

Each Khadanza block is fixed for a marketing price of Rs. 27.00 which means Rs. 3807 per

cu.m as against Rs. 5,500 per cu.m of M25 grade concrete from site mix or from RMC.

Even after taking cost of transport additionally, still khadanza pavement is cost effective.


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Khadanza Pattern – Orientation of Blocks

Page | 1

DETAILED PROJECT REPORT

FOR

PRODUCTION OF COMPRESSED STABILIZED

EARTHEN/ SOIL/ MUD BLOCK

Based on the Recommendations of the Working Group Ministry of Rural Development

Government of India July - August 2015

Centre for Rural Infrastructure (CRI) NATIONAL INSTITUTE OF RURAL DEVELOPMENT & PANCHAYATHI RAJ

(NIRDPR)

Rajendranagar, HYDERABAD- 500 030

Page | 2

CONTENTS

INTRODUCTION ...................................................................................................................... 3

MATERIALS ............................................................................................................................. 4

BROAD GUIDELINE TO SELECT OR MODIFY SOIL FOR THE PRODUCTION OF CSEB: .............. 4

PRODUCTION STAGES: ........................................................................................................... 5

DIMENTIONS AND TOLERANCES: ........................................................................................... 8

BLOCK PRESS MACHINES: ..................................................................................................... 10

TYPICAL BLOCK-YARD ORGANISATION: ................................................................................ 10

COST BREAK UP OF CSEB ...................................................................................................... 11

ADVANTAGES AND LIMITATIONS: ........................................................................................ 12

SPECIFICATIONS FOR COMPRESSED STABILIZED EARTH / SOIL/ MUD BLOCKS: .................. 13

Page | 3

INTRODUCTION

Earth as a construction material has been used for thousands of years by civilisations all over the world. It is the most abundant building material known and available in majority of the locations. The ttraditional soil construction methods in the country are cob (mixture of straw, gravel and clay), wattle and daub - (coarse basket work of twigs woven between upright poles and plastered with earth) and adobe – (roughly moulded, sundried clay bricks). The main drawback of these types of earth construction is their lack of durability, further research is required so as to improve their quality. Compressed Stabilized Earth Block (CSEB) is one of such technology, in which blocks are made by compressing earth/ soil mixed with Suitable stabilizer (cement/ lime) at optimum moisture content by simple mechanical means. Densification of soil at Optimum moisture content and use of stabiliser make CSEB durable and it does not soften due to action of the water. Production of CSEB generates employment to the unskilled labour. Baking is not required thus it is environmental friendly practice. This blocks can be used in construction of houses, government buildings, Toilets, etc.

Page | 4

MATERIALS

Materials required for construction of Compressed Stabilised Earth Blocks (CSEB) are as

follows:

Cement: The cement shall confirm to either IS 269 or IS 1489 (Part-1) or IS 8112 or IS

12269.

Lime: Lime shall confirm to IS 712

Sand: The sand to be used for diluting the soils shall be either natural river sand, crushed

stone sand or crushed gravel sand confirming IS 383. It should be free from any type of

salt/ chemical and organic matter.

Soil: Soil shall be of the quality suitable for the production of stabilized soil blocks.

Generally, soil contains clay minerals and inert particles such as silt and sand. The

percentage and type of clay mineral controls the characteristics of soil. In majority of the

cases the clay mineral content of the soil has to be controlled and adjusted by diluting the

soil with sand, in order to make the soil suitable for CSEB.

Water: The water to be used in the manufacture of blocks shall not be detrimental to its

durability.

BROAD GUIDELINE TO SELECT OR MODIFY SOIL FOR THE PRODUCTION OF CSEB:

The soil or soil-sand mixture meeting the specification given in Table-1 may result in

production of good quality stabilized blocks. The recommended values of stabilizer to clay

ratio for expansive and non-expansive soil have been given in Table-2.

Table 1: Recommended specification for soil or soil-sand Mixture

S. No. Details Limiting value

1 Granular composition of soil-sand mixture:

a) Clay fraction (< 0.002 mm) 5%-18%

b) Silt fraction (0.002-0.075mm) 10%-40%

c) Sand fraction (0.075-4.75mm) 50%-80%

d) Gravel fraction (4.75-6mm) 0%-10%

2 Liquid limit Less than or equal to 30%

3 pH 6.5 – 8.5

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Table 2: Recommended Stabilizer to Clay Ratio for Different Types of Soils

S. No. Type of soil Stabilizer to Clay Ratio (by

Weight)

1 For soils having non-expansive clay minerals

(for example, kaolinite, illite, etc.)

More than or equal to 0.40

2 For soils having expansive clay minerals (for

example, montmorillonite)

More than or equal to 0.75

Note: Stabilizer content should be more than or equal to 5% (by Weight)

Use of soil containing expansive clay minerals such as montmorillonite requires lime as a

stabilizing additive to manufacture CSEB. Acidic soils having pH less than 6.5 can be

stabilized with addition of 1 to 2 percent calcium hydroxide (lime) by weight in addition to

cement. Soil containing excessive silt fraction can lead to CSEB having very low green

strength for handling during block manufacturing process. In such situations, coarse gravel

or coarse sand fraction can be added to the soil to overcome the problem.

PRODUCTION STAGES:

Stages involved in production of CSEB are as follows:

1) Site Identification for Borrow pit:

The borrow pit is a source of raw soil for the production of CSEB. It should not be too far

from the production site in order to reduce transportation costs of the raw material.

Sufficient soil must be available from the borrow pit to satisfy the proposed scale of

production. Before any major action takes place, soil samples from trial holes must always

be taken to check the adequacy of the soil and to be able estimate available amounts. Soil

composition can vary greatly even within a small area so several test holes should be dug

to give a full picture of the type of the soil within a borrow pit.

Laboratory analysis of the raw material is always necessary for large-scale production of

compressed stablised earth blocks. Before going for it, Simple field tests can be performed

to get an indication of the composition of the soil sample. Such tests are discussed briefly

below.

Smell test: Smell the soil immediately after it has been sampled. If it smells musty it

contains organic matter. This smell will become stronger if the soil is heated or wetted. Soil

containing organic matter is not suitable for production of compressed stabilised earth

blocks.

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Touch test: Remove the largest grains and crumble the soil by rubbing the sample between

the fingers and the palm of the hand. If it feels rough and has no cohesion when moist the

soil is sandy. If it feels slightly rough and is moderately cohesive when moistened the soil is

silty. If, when dry, it contains lumps or concretions which resist crushing, and if it becomes

plastic and sticky when moistened the soil is clayey.

Sedimentation test: The tests mentioned previously make it possible to form a general

idea of the texture of the soil and the relative particle sizes of the different fractions. To

obtain a more precise idea of the nature of each soil fraction, a simplified sedimentation

test can be carried out in the field. The apparatus required is straight forward: a

transparent cylindrical glass bottle with a flat bottom and a capacity of at least one litre,

with a neck wide enough to get a hand in and a lid to allow for shaking. Fill the bottle to

one-third with clean water. Add approximately the same volume of dry soil passed through

a 6mm sieve and add a teaspoonful of common salt. Firmly close the lid of the bottle and

shake until the soil and water are well mixed. Allow the bottle to stand on a flat surface for

about half an hour. Shake the bottle again for two minutes and stand on level surface for a

further 45 minutes until the water starts to clear. The finer particles fall more slowly and as

result will be deposited on top of the larger size particles. Two or three layers will emerge,

with the lowest layer containing fine gravel, the central layer containing the sand fraction

and the top layer containing silt and clay. The relative proportions, and hence percentages,

of each fraction can be determined by measuring the depth of each layer.

Image 1: Sedimentation test

Image 2: Adhesion test

With field tests and laboratory tests, suitable site for borrow pit to be identified as per soil

specifications given in table-1.

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2) Soil Preparation:

In order to have uniform soil, it is necessary to crush it so that it can pass through a 6mm mesh

sieve. It is then to be sieved through a 6mm sieve to remove gravel, lumps of clay, roots,

etc. If the soil gradation is to be changed by adding sand/ quarry dust or clayey soil, this

addition is to be done now. The operation of block making is always carried out in batches.

The batch size can generally vary between 25 to 50 blocks per batch, for manually

operated block press machine. The quality of mixing may suffer if a larger batch size is

attempted. For larger batch sizes, mechanical mixing may have to be thought of.

3) Mixing of soil and stabilizer:

As per table-2 quantity of stabilizer for given type of soil is to be ascertained. In order to

achieve satisfactory mixing, the selected soil quantity must be spread as a thin layer of

about 15cm in thickness. The appropriate stabilizer quantity now spread as a thin layer on

the soil. The soil and stabilizer are now mixed initially with spade and subsequently with

hand. The mixing is completed when the mixture attains a uniform colour.

4) Addition of Moisture:

At the outset, the amount of moisture to be added may be estimated approximately. A

sandy soil will usually need 10% to 12% water for optimum moisture content (OMC).

Water for optimum moisture content is to be sprinkled on the soil stabilizer mixture which

is spread thinly on level ground. The soil and water are mixed thoroughly by hand the

process is repeated with remaining water. The adequacy of moisture is now checked by

making a ball out of moist soil. If a ball can be made without the soil sticking to the hand

the moisture content is optimum. If ball cannot be made, the mixture is below OMC and

small quantity of water may be added and again checked for OMC. The moist soil plus

stabilizer mixture is now ready for block pressing.

5) Block pressing:

The Block press machine should be anchored in position. The moist mixture of soil and

stabilizer may now be taken in a scoop and weighed. The weight of the soil should be such

that desired block density is achieved. The stabilized soil mixture is now poured in to the

mould through quick up and down motion of scoop. It is to be compacted in the block

press machine to a CSEB block.

6) Block ejection and stacking:

The block is to be ejected from the block press machine, removed from the mould and

taken for stacking. The machine is now ready for next block. Fresh blocks may be stacked

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on a leveled ground under polythene sheet to avoid quick loss of moisture. The stacking

yard should be as close to the machine as possible. The blocks may be stacked one above

the other up to six layers.

7) Curing of the blocks:

The blocks must be cured for 21 days by gently sprinkling moisture. Strawn or Gunny bags

may be used to cover stack. Alternatively block may be cured for 7 days in stack and then

used for wall construction. The further curing for 14 days must be pursued in the wall

wherein it is often necessary to cure mortar as well.

DIMENTIONS AND TOLERANCES:

The Modular size of stabilised Earth blocks shall be as follows:

Length (mm) Width (mm) Height (mm)

290 90 90

290 140 90

240 240 90

190 90 90

190 90 40

The dimensions of the units are so designed that taking account of mortar joints, they will produce wall lengths which will confirm to the principles of modular co-ordination.

The following non-modular sizes of the bricks may also be used:

Length (mm) Width (mm) Height (mm)

305 143 100

230 190 100

305 143 100

230 190 100

230 105 75

230 105 100

Tolerances: The maximum variation in the dimensions of the units shall not be more than +/- 2mm.

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Frog: Each block may have frogs on both the bed faces in the form of depression of rectangular or square shape with depth not excceding 10mm. In such cases, the area of the frogs on each bed face shall be restricted to 25 percent of the surface area and it is preferable to have at least one frog on either face.

PHYSICAL REQUIREMENTS:

Sr.

No. Parameter Requirements

1 Dry Density of the Block The dry density of the blocks, being the

average of three specimens, when determined

in accordance with the procedure prescribed

in Annex C of IS1725, shall not less than 1750

kg/m^3

2 Compressive strength The minimum average compressive strength

of blocks when determined in the accordance

with the procedure described in IS3495 (Part-

1) shall 3.5 Mpa (35kg/cm^2)

The compressive strength of any individual

block shall not fall below the minimum

average compressive strength by more than

15%.

3 Water absorption The average water absorption of the blocks

when determined in accordance with the

procedure prescribed is IS3495 (Part2) after

immersion in cold water for 24hr shall not be

more than 18 percent by weight

4 Linear expansion on saturation

of the blocks

The linear expansion on saturation of the

blocks, being the average of three specimen,

when determined in accordance with the

procedure described in Annex D of IS1725,

shall not exceed 0.10%

5 Weathering The maximum loss of weight , being the

average of three specimens, when determined

in accordance with the procedure described in

Annex E of IS 1725, shall not exceed 3%

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BLOCK PRESS MACHINES:

Suggestive block press machines suitable for CSEB production under MGNREGS with their suppliers is given below.

Mardini Block Press

Maheemaya, 65/108,

Bilekahalli, Bannerghatta

Road, Bangalore-560076

e-mail:

[email protected],

[email protected]

Phone: (080)2658 2970

Auram Press 3000

Aureka, Aspiration,

Auroville, Tamil Nadu –

605101

e-mail:

[email protected]

Phone: (0413)2622278/

2622134/ 2622651

Fax: (0413) 2622274

TARA machines and Tech

services Pvt. Ltd.

B-32, TARA Crescent, Qutab

Institutional Area,

New Delhi - 110 016

e-mail:

[email protected]

Cell No:

09599222036, 09599787054

TYPICAL BLOCK-YARD ORGANISATION:

Persons required at different stages of the block production, with manually operated block

press machine, may be given as:

Sr.

No. Stages of block production Number of persons required

1 Soil Preparation: 2 to 4 persons

2 Mixing of soil and stabilizer 2 persons

3 Addition of Moisture 2 persons

4 Block pressing: 3 persons

5 Block ejection and stacking: 1 person

6 Curing of the blocks: 1 person

Total 11-13 persons

Note: Data given above is suggestive. Actual number of person required, depends on Type

of block press machine, type of soil, transportation distance for raw material and block

produced, etc.

mailto:[email protected]




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Key words for the organisation of the block-yard:

Reduce the distance of transportation

Optimise the ratio output / number of workers to get the best efficiency.

Organise the block-yard as close as possible from the site.

Organise the store room as close as possible from block yard.

Organise the final stacking area as close as possible from the block yard.

It is preferable to have linear organisation but circular one can also be suitable.

COST BREAK UP OF CSEB

1 Fixed capital Unit Cost (Rs)

Land, Shed and Storage 500 sqm 300,000.00

Submersible with pump 1 No 50,000.00

Pressing machine & all accessories 1 No 120,000.00 (Minimum)

Other miscellaneous Lum sum 600,00.00

Total 5,30,000.00

2 Recurring expenditure for 1000 blocks of size 230X105X75mm

Item Qnty Unit Rate (Rs) Cost (Rs)

Manpower per day: 13.00 Nos 160 2,080.00

Cement 4.00 Bag 320 1,280.00

Soil 4.00 M3 150 600.00

Sand /quarry dust 0.40 M3 200 80.00

Lime 4.00 KG 12 48.00

Water 600.00 Liters 1 600.00

Press machine charges and interest rate per day 677.00

Total 5,365.00

3 Cost analysis ratio

Production capacity 1000/ Per Day

Per Day Expenditure Rs 5365.00

Cost for each Brick Production Rs 5.37

4 Wage Material ratio

Unskilled wage component Rs 2080.00 (44.37%)

Material component Rs 2608.00 (55.63%)

Note: In general the labour cost (which includes the soil digging, its preparation and the block making) is highest. Therefore if the productivity decreases, the cost of the block will increase proportionally a lot. In general, to reduce the cost of the block one should optimize the productivity of workers.

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ADVANTAGES AND LIMITATIONS:

Advantages:

Can be very cost effective, especially when the blocks are produced at the site of use

Soil is an easily available resource in rural housing

Provides good thermal comfort

Provides aesthetical wall finish, no plaster required

Creates additional local employment in block production

Can be made with locally available earth which makes it cost effective.

Thermally comfortable, aesthetically pleasing and one of the most environment

friendly alternatives for wall construction.

Limitations:

Requires a good understanding of the type of soil available for block production and

how it can be improved/ stabilized.

Availability of soil in adequate quantity from a single source, can be a limitation.

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SPECIFICATIONS FOR COMPRESSED STABILIZED EARTH / SOIL/ MUD BLOCKS:

IS 1725: Stabilised soil blocks used in general building construction- Specification

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Pradhan Mantri Awas Yojana - Gramin (PMAY-G) · Author: ILOVEPDF.COM Created Date: 9/7/2015...

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Transcript of Pradhan Mantri Awas Yojana - Gramin (PMAY-G) · Author: ILOVEPDF.COM Created Date: 9/7/2015...