Non-Fired Brick Alternatives for Bangladesh Compressed Stabilized Earth Blocks � Hollow Concrete Blocks

Final project report by Building Pioneers

20 March 2018

Table of Content

A WORD OF THANKS TO OUR SUPPORTERS 3

PROJECT RESULTS AT A GLANCE 4

OVERVIEW: FCB, CSEB and HCB 5

THE PROJECT IN MORE DETAIL 6

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

ATTACHMENTS

Transformation of FCB kilns into HCB factories 8

CSEB strength test results 17

Soil testing report 23

Pictures of the CSEB pilot production in Bangladesh 26

Addressed readers

This report addresses individuals and organizations working on the development and production of brick alternatives in Bangladesh, including the government, governmental organizations (e.g. the Housing and Building Research Institute), development programs (e.g. switch-asia), NGOs (e.g. UNDP, Oxfam), private sector companies and entrepreneurs.

Purpose of this report

This report provides important information and lessons learnt from Building Pioneers’ test production of Compressed Stabilized Earth Blocks (CSEB) and research on Hollow Concrete Blocks (HCB).

The purpose of this report is to facilitate the right choice of block types for Bangladesh. By sharing what has already been researched and implemented, we aim to avoid the repetition of mistakes and direct resources to viable options.

Contact details for more information

Building Pioneers supports individuals and organizations who aim to establish brick alternatives in Bangladesh. If we can help you, please visit our website or contact us directly:

Building Pioneers UG (charitable limited) www.building-pioneers.com

Ava Mulla, Co-Founder, CEO ava.mulla@building-pioneers.com

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We want to thank the individuals and organizations that supported us in our ambitious endeavour. Thanks to their support, we could realize the largest and most systematic test production of Compressed Stabilized Earth Blocks in Bangladesh. Sharing our results and lessons learnt contributes to the on-going efforts to develop and implement brick alternatives in Bangladesh.

Our biggest thanks goes to Thomas Knaack, successful entrepreneur and business angel, for his major financial contribution. Thomas has been a vital part of our journey from the idea stage, through the foundation of Building Pioneers, until the end of our project in Bangladesh. He shared our vision and believed in our ability to make it happen. Thank you very much!

We would also like to thank the Munich Re Foundation, the Google Impact Challenge and the enorm magazine for their generous financial contributions. As a young social enterprise, we are grateful for early-stage funding opportunities and public exposure.

Thanks to Dr. Mohammad Shariful Islam from BUET for his passionate and tireless support and his invaluable moral backing through times of unforeseen difficulties. Dr. Islam is a key figure in improving living conditions and resilience in rural Bangladesh.

Thanks to BUET (Bangladesh University of Engineering and Technology) for their laboratory testing facilities.

Thanks to Social Impact Start for granting us a start-up scholarship and free office space in Hamburg, Germany. Thanks to the International Centre for Climate Change and Development (ICCCAD) and especially its director Dr. Saleemul Huq for great networking opportunities and personal encouragement.

Bangladesh University of Engineering and Technology

Thomas Knaack Dr. Md. Shariful Islam

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A WORD OF THANKS TO OUR SUPPORTERS

4

Major players in transforming FCB kilns into HCB factories

Government

Enforce existing regulations to increase pressure on brick kiln owners to either shut down, upgrade or switch to HCB production.

Offer soft loans and other financial incentives (e.g. purchase guarantees for governmental construction projects) to early adopters of HCB production.

Development programs & NGOS

Realize a pilot transformation as a proof of concept. Promote this case study among key stakeholders incl. a detailed cost analysis and technical assessment.

Create a “transformation package” by engaging key stakeholders: financial institutions for funding, private sector for machinery and training, universities for research and testing, developers for contracts, etc.

Involve brick kiln owners from the start. They should remain in business; their existing infrastructure and knowledge of the brick market will facilitate the shift.

Private sector companies

Especially HCB machine suppliers (China and India) can play a key role in creating the pilot factory which show cases and promotes HCB production. The transformation of countless brick kilns into HCB factories is an untapped business opportunity.

Key results of the project on non-fired brick alternatives

Fired Clay Brick (FCB) production in Bangladesh causes severe environmental damage incl. high CO2 emissions, air pollution, deforestation and topsoil depletion. FCB are the most widely used building material in Bangladesh.

Compressed Stabilized Earth Blocks (CSEB) are a non-fired alternative to FCB in various countries. However, CSEB is not a suitable building material for Bangladesh; see explanation below.

Hollow Concrete Blocks (HCB) is a viable non- fired alternative to FCB in Bangladesh. Compared to FCB, HCB reduce CO2 emissions by 50%, cause no air pollution, no deforestation and no topsoil depletion. HCB construction is cheaper than FCB.

Recommendations by Building Pioneers

1.  Transform FCB kilns into HCB factories in parts of Bangladesh where course sand is locally available or cost effective to buy – mainly in the north and east. See details below

2.  Modernize out-dated FCB kilns in parts of Bangladesh where HCB cannot be produced cost competitively due to the price of course sand – mainly in the south of Bangladesh.

3.  Introduce more innovative building materials to Bangladesh such as wood-plastic composites (WPC), engineered bamboo etc. Bangladesh has a high demand for eco-friendly, affordable and disaster resistant construction.

PROJECT RESULTS AT A GLANCE

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Compressed Stabilized Earth Blocks (CSEB)

Mix of soil, sand, cement and water compressed, air dried, cured with water

Environmental impact

The CO2 emissions are approx. 50% lower than FCB. No burning process is required, hence no air pollution is caused. No top soil is depleted. However, the use of subsoil lowers the surface level, making land more prone to flooding and thus affecting the agricultural yield.

Technical characteristics

The requirements for safe and long term use in Bangladesh are not met: CSEB’s inherent low wet compressive strength and accelerated deterioration in wet environments poses a risk to health and safety when used in flood prone areas. The inconsistent composition of soil prevents a reliable block quality.

Cost advantage over FCB

The cost advantage of CSEB over FCB is questionable: Locally available soil is unsuitable for CSEB production and has to be supplemented with course sand. A higher cement content is required to improve the CSEB’s technical performance. Both increase the cost of raw materials significantly.

Fired Clay Bricks (FCB)

Mix of clay and water, moulded in the shape of a brick, sun dried, fired in a kiln

Environmental impact

The production of 18 billion FCB per year in approx. 7000 kilns consumes 3.5 million tonnes of coal and 2 million tonnes of firewood. This causes 6 million tonnes of CO2, 40% of Dhaka’s air pollution and severe deforestation. Top soil depletion destroys fertile farmland on a large scale.

Technical characteristics

FCB are load bearing and water resistant, thus suitable for foundations and flood prone areas. Their inconsistent shape and size however requires large amounts of mortar and plaster, adding significantly to construction costs.

Hollow Concrete Blocks (HCB)

Mix of sand, cement and water compressed under vibration, air dried, cured with water

Environmental impact

The CO2 emissions are approx. 50% lower than FCB. If using cement with fly ash, the CO2 emissions are even lower. In contrast to CSEB and FCB, HCB do not contain soil which solves the issue of soil depletion. Dredging river sand, if done responsibly, does not harm the environment.

Technical characteristics

HCB outperform CSEB and FCB in key characteristics incl. compressive strength and durability. The production process is robust and easily scalable. Compared to FCB, HCB have higher dimensional accuracy and can be reinforced to withstand earthquakes.

.

Cost advantage over FCB

HCB construction can achieve a cost advantage of approx. 25% over FCB construction. While the cost of bricks and blocks per sqm wall is comparable, the cost advantage derives from reduced mortar and plaster use and lower labour cost due to higher construction speed. .

OVERVIEW: FCB, CSEB and HCB

3) Conclusion

Our project revealed that Compressed Stabilized Earth Blocks (CSEB) are not a suitable building material for Bangladesh. The technical requirements for safe and long term use were not met. The cost advantage of CSEB over fired clay bricks is questionable. The expected environmental benefits proved partly true (no air pollution, lower CO2 emissions) and partly wrong (impact on farmland).

Instead, we recommend hollow concrete blocks (also called sandcrete blocks or cinder blocks). Furthermore, we urge to upgrade or shut down brick kilns, which cause severe environmental damage and introduce more innovative building materials to Bangladesh.

1) Project goal and approach

The goal of this project was to establish Compressed Stabilized Earth Blocks (CSEB) as an eco-friendly, cost effective and disaster resistant alternative to conventional building materials such as fired clay bricks and corrugate iron sheet in Bangladesh.

In order to determine the technical properties, financial viability and market acceptance of CSEB in the local context, we set-up a CSEB pilot production; we analysed soil samples from various regions in Bangladesh and set up a production site in Shariatpur, 60km south of Dhaka, where we produced nearly 2000 blocks in 40 different raw material mixes and 5 shape variations. The blocks then underwent thorough testing at the laboratory of BUET (Bangladesh University of Engineering and Technology).

The project was run by the German social business Building Pioneers in collaboration with Inclusive Home Solution Ltd.

2) Brief introduction to CSEB

CSEB stands for Compressed Stabilized Earth Blocks. CSEB are blocks made of soil, sand and a stabilizer (cement or lime). The raw materials are mixed with water, compressed in a machine and then left to air dry; no firing process is involved.

Compressed Stabilized Earth Blocks (CSEB) can be a viable alternative to conventional building materials in developing countries. In many cases CSEB are more cost effective and environmentally friendly than widely used fired clay bricks, concrete blocks or corrugated iron sheet. CSEB can also be produced in multiple shapes, making it a versatile and aesthetically pleasing building material. Various countries in South America, Africa and Asia have successfully implemented CSEB projects.

Building Pioneers does not recommend the production and use of CSEB in Bangladesh. Instead, we promote the transformation of Fired Clay Brick kilns into Hollow Concrete Block factories.

4) Remarks

It is a founding principle of Building Pioneers to develop financially viable and scalable solutions rather than donation based activities. If a product does not meet the technical requirements, fulfil environmental standards and find customer acceptance, we do not promote its use.

We encourage other organizations, especially non-profits, development agencies and government organization to redirect their resources towards research, development and implementation of marketable products and services.

During its project, Building Pioneers witnessed the inefficient use and wastage of donor funds in established organizations, preventing tangible progress in improving Bangladesh’s building materials.

We recommend a strong private sector engagement in order to achieve useful outcomes that outlive the flow of donations. 6

THE PROJECT IN MORE DETAIL

•  The soil composition in most regions of Bangladesh is not suitable for the production of CSEB. Modification of the excavated soil is required, which increases production costs. A textbook soil composition for CSEB is 15% gravel, 50% sand, 15% silt and 20% clay. None of our 20+ soil samples contained an adequate ratio of sand and clay; soils were either too clayey or too sandy. None of our samples contained any gravel. The only viable option is to add course sand to clayey soil. However, course sands like Sylhet sand are considerably more expensive than fine sand.

•  CSEB do not achieve a substantial cost advantage – if any – over fired clay bricks due to raw material prices and the soil drying procedure. A large open space is required to spread the excavated soil for drying. The process proved to be more labour and time intense than predicted. Only on sunny days during the dry season (March till October), soil dried quickly. Still, large chunks had to be manually chopped into smaller pieces to allow for drying. Days with overcast and high humidity delayed the process. Only bone-dry soil could be processed in the soil crusher; any moisture clogged up the machine.

•  CSEB are overall more environmentally friendly than FCB: CSEB production does not cause air pollution or direct CO2 emissions as there is no firing process involved; however, the environmental impact of cement has to be considered.CSEB have lower CO2 emission than fired clay bricks; approximately 50%, depending on the cement* content – usually between 5% and 8% by volume. CSEB production does not deplete agricultural topsoil, however, the excavation of nonorganic subsoil still negatively impacts farming by lowering the surface and thus making land more prone to flooding. Given the high population density of Bangladesh, farmland is scarce and has to be protected for food production.

6) Close-up: HCB

•  Hollow concrete blocks (HCB) are a promising alternative to FCB especially for the northern and eastern regions of Bangladesh where course sand is widely available, as well as for urban areas. HCB consist of gravel, sand and cement. If gravel is not available, course sand can serve as a substitute. HCB are cost competitive to FCB while offering superior technical properties. Provided that sand is sourced responsibly from legal queries which adhere to environmental standards, HCB’s impact is limited to the CO2 emissions from the cement, which are significantly lower per wall area built than the CO2 emissions of FCB. Using cement that contains fly ash, the CO2 footprint can be reduced even further. HCB are used in developing and industrialized countries around the world. Comprehensive guidelines for production and testing as well as building codes (e.g. earthquake strengthening) exist. Cost effective state-of-the-art machinery for HCB production is widely available in nearby countries including India and China.

7) Close-up: CSEB

•  CSEB are not suitable for the weather conditions of Bangladesh (heavy monsoon rain, frequent flooding); CSEB’s inherent characteristics are a low wet compressive strength and accelerated deterioration in moist environments. This poses a threat to the structural integrity of buildings and therefore the health and safety of people. A higher cement content would improve the technical properties but also substantially increase the production cost, making them more expensive than fired clay bricks and therefore not competitive.

* The production of 1kg of cement emits approximately 1kg of CO2

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THE PROJECT IN MORE DETAIL

Transformation of FCB kilns into HCB factories ATTACHEMENTI

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Out-dated brick kilns can be transform into state-of-the-art hollow concrete block factories

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Approx. 2,000 kilns qualify for transformation: they are required to upgrade and are located in regions where suitable raw materials for blocks are available.

46 17

28

101 60 37 17

56 19

103 42

91 63

43 42 22

164 61 32 98

66 50

66

43

57 177

119 63

54 82 30

76 33

93

64 89 39

16

17 18 10

136 35 20

298

28 14

17 58

95 73 75

135 68 46

28 22

70 34 51 182

225

* Remarks: Map from 2006, total number of kilns: 4140 Total number of kilns today: 7000

High demand for transformation

à More than 2,000 brick kilns qualify for transformation to block factories

7,000 3,500

2,100

Approx. 7000 kilns are in operation

60% of those are located in the North, where raw materials for blocks are locally available

50% are legally required to upgrade or shut down (FCK)

Number of brick kilns* in respective region of Bangladesh

Regions with suitable raw materials at competitive price

Previous attempts to upgrade Fixed Chimney Kilns (FCKs) to state of the art Hybrid Hoffman Kilns (HHK) on a large scale failed due to high initial investment and land requirements

Current policy to upgrade to Zig Zag kilns does not solve key issues incl. topsoil depletion

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HCB is a proven and widespread technology. China is the leading country. Machines are available in various sizes.

Machine type Large Medium Small * HCB output per 8 hour shift (40cm x 12.5cm x 20cm) 7,000 4,300 3,600

Output in FCB equivalent (FCBE = same wall area) ** 31,000 19,000 16,000

Cost of machinery 19,00,000 BDT (19 lakh) 9,70,000 BDT (9.7 lakh) 7,80,000 BDT (7.8 lakh)

Other costs (import, site preparation, installation, etc.) 6,60,000 BDT (6.6 lakh) 5,00,000 BDT (5 lakh) 4,50,000 BDT (4.5 lakh)

Moveable on a seasonal basis e.g. in case of low-lying land No Yes Yes

Cement consumption per day 8,900 kg 5,500 kg 4,600 kg

Large Medium Small

* Even smaller machines are available which are mobile and therefore suitable for temporary production sites, e.g. in remote areas ** 1 HCB covers 4.4 times more wall area than 1 FCB (800 cm2 vs. 180 cm2). Therefore, 1 HCB is equivalent to 4.4 FCB in terms of wall construction.

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Comparison of mortar joints in Fired Clay Brick (FCB) and Hollow Concrete Blocks (HCB) walls

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The dimensional accuracy of Hollow Concrete Blocks allows thin mortar joints and is aesthetically pleasing without plaster

The great variation in shape and size of Fired Clay Bricks requires large amounts of mortar.

Wall construction with Hollow-Concrete-Blocks (HCB) is approx. 25% cheaper than Fired Clay Bricks (FCB)

Comparison of properties

Particulars Unit FCB HCB Comparison of HCB to FCB

Brick / block dimensions cm2 inch2

24 x 11.5 x 7.5 9.5 x 4.5 x 3

39 x 14 x 19 16 x 6 x 8 5 times more volume

Wall area covered per brick/block cm2 180 800 4 times more wall area

Pieces for 1 m2 wall pcs 44 12.5 31 pieces less

Amount of mortar per m2 wall litre 30 9 21 litres less mortar

Wall area covered by mortar joints % 22% 10% 55% less

Cost comparison of wall construction

Particulars Currency

1 m2 FCB wall (5”)

1 m2 HCB wall (6”)

Cost Comparison of HCB to FCB walls

Cost of bricks / blocks BDT 352* 400* 0 %

Cost of mortar BDT 243 188 - 70 %

Cost of labour BDT 321 (plastered) 50 (unplastered) - 55 %

Total cost BDT 916 638 - 28 %

44 FCB 12.5 HCB

* incl. transportation cost:1 Tk per FCB, 4-5 Tk per HCB 13

HCB production is more attractive than FCB. It requires less initial investment, less land, less manpower and lower energy consumption.

Particulars Fixed Chimney Kiln (FCK)

Hybrid Hoffmann Kiln (HHK)

Hollow Concrete Block Factory (HCB)

HCB vs. FCK

HCB vs. HHK

Initial investment 40,00,000 BDT 320,00,000 BDT 25,60,000 BDT - 36% - 92%

Land requirement 2.5 acres 2.5 acres 0.30 acres - 88% - 88%

Yearly output (duration of production season)

2 - 2.5 Mio. (6 months)

7.5 - 9.0 Mio. (11 months)

5.6 Mio.* (6 months) 10 Mio. * (11 months)

+ 124% + 11%

Fuel consumption 20 - 24 tons of coal per 1,00,000 FCB

12-14 tons of coal per 1,00,000 FCB

17,700 litres per 1,00,000 FCBE *

- -

CO2 emission 67 tons per 1,00,000 FCB

46.9 tons per 1,00,000 FCB

28.9 tons per 1,00,000 FCBE *

- 56% - 38%

Labour requirement** 150 65 20 - 87% - 69%

Cement consumption per year

- - 1,600 tons (6 months) 2,900 tons (11 months)

* FCBE = FCB equivalent (see previous slide) ** A reduction of the labour force in brick production means a loss of income for some of the 1 million workers involved in this industry. This negative effect can be compensated through masonry training or other programs. Assumption: more solid houses will be built, because HCB make solid housing more affordable.

Source of HHK, FCK data: Imran, 2014 14

The market potential is huge: at approx. 25% cost advantage, HCB are a substitute for FCB and part of the CI sheet market.

Source: BBS, Household Income & Expenditure Survey (HIES), 2010; remark: the remaining percentages comprise other wall materials

Percentage of houses built with different roof and wall materials

In Bangladesh, 25% of dwelling units are constructed with bricks. Another 37% use CI-sheet (tin) for walls. The demand for bricks is high and growing. There are approx. 6400 FCB kilns that produce 17 billion bricks per year. Currently, FCB are the only widely available solid building material in Bangladesh. The brick market is expected to grow at 5% over the next 10 years.

Roof material Corrugated iron sheet (CI) Concrete

Wall material

Straw, bamboo Mud brick, wood CI sheet Brick

Rural Bangladesh 18% 16% 42% 10% 3%

Urban Bangladesh 10% 5% 24% 29% 28%

National 16% 13% 37% 15% 10%

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à Other maps on disaster prone areas, income level, kiln locations, urban / rural ratio, land ownership etc. are required identify the low-hanging fruit customers and the most suitable approach (part of pilot project)

Building Pioneers identified 2 main customer groups according to their income level: a) brick choice group and b) brick gap group.

Brick choice group

This group cannot afford FCB, but can afford HCB due to the 25% cost reduction. The brick gap group strives for solid housing but currently sits in the “affordability gap” between CI and FCB.

The brick choice group is likely to be found where FCB houses are common (dark blue)

The brick gap group is likely to be found in areas with sufficient income level for HCB but low brick supply (e.g. scarcity of soil)

This group can afford FCB, but chooses HCB to a)  Reduce cost b)  Build bigger at same price c)  Build earthquake resistant d)  Achieve better aesthetics

and lightweight (high rise)

BDT

FCB

CI

HCB

Income level

Construction cost

BDT

FCB

CI

HCB Income level

Construction cost

Brick gap group

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CSEB Strength Test Results ATTACHEMENTII

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General remarks

General remarks •  The CSEB in this testing series are produced by Building Pioneers and IHS Ltd. in November 2015 in Shariatpur, Bangladesh. •  The testing series contains 41 different batches. Each batch is composed of a unique ratio of soil, course sand, fine sand and cement,

reflected in its ID code: The cement ratio varies between 5% and 8%, the sand ratio between 20% and 60%. •  All CSEB batches contain the same type of soil, composed of 60% silt and 40% clay. •  As a stabilizer, Ordinary Portland Cement (OPC) was used. •  The CSEB were compressed in an AURAM 3000 press, developed and supplied by the Auroville Earth Institute, India. •  The CSEB were tested in BUET’s laboratory (Bangladesh University of Engineering and Technology) under the supervision of Prof. Md.

Shariful Islam. ID code of mixes •  Each mix has a unique ID code of 3 to 4 digits that indicates the soil-sand-cement ratio and the sand type. •  The first digit (C, F or M) stands for the sand type that was added to the soil. C means that only course sand was added, F means only

fine sand, M means a mix of course and fine sand. •  The second digit (2, 3, 4, 5 or 6) stands for the sand ratio 2 means 20%, 3 means 30% and so on. The rest (100% - sand ratio) is soil.

Hence, soil + sand always amounts to 100%; the cement ratio is relative to the 100% soil-sand mix. •  The third digit (5, 6, 7 or 8) stands for the cement ratio. 5 means 5%, 6 means 6% and so on relative to the 100% soil-sand-mix. •  Some of the mixes with an M as a first digit have a fourth digit (C+ or F+). This indicates in which ratio course and fine sand were mixed.

C+ means 2/3 course sand + 1/3 fine sand. F+ means 2/3 fine sand + 1/3 course sand. The mixes with an M as a first digit and no fourth digit contain a 50/50 ratio of course and fine sand.

Examples •  C38: 30% course sand + 70% soil = 100% --> 8% cement based on total soil-sand mix •  F45: 40% fine sand + 60% soil = 100% --> 5% cement based on total soil-sand mix •  M46: 40% sand which is 50/50 fine and course + 60% soil = 100% --> 6% cement based on total soil-sand mix •  M56F+: 50% sand which is 2/3 fine and 1/3 course + 50% soil = 100% --> 6% cement based on total soil-sand mix •  M36C+: 30% sand which is 2/3 course and 1/3 fine + 70% soil = 100% --> 6% cement based on total soil-sand mix

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Crushing strength [psi] of 5 samples in DRY condition

Rounded average crushing strength [psi] of 5 samples in DRY condition by group type

Laboratory number

ID code of mix 1 2 3 4 5 Average

[psi]

Rounded average

[psi]

Rounded average [MPa]

Group 1 (C) Sand mix: 3/3 course

20 M56F+ 740 870 890 1020 880 880 880 6,1 28 F45 810 760 950 560 800 776 780 5,4 20% 30% 40% 50% 60%32 M46C+ 830 720 800 720 760 766 770 5,3

cement 5% 490 290 560 390 620

24 M45F+ 700 880 790 650 840 772 770 5,3 6% 340 460 630 690 13 M46 770 680 820 830 690 758 760 5,2 7% 23 M68F+ 740 600 410 1140 910 760 760 5,2 8% 510 750 470 3 C38 640 880 890 630 710 750 750 5,2

33 M56 780 830 600 840 620 734 730 5,0 Group 2 (MC+) Sand mix: 2/3 course + 1/3 fine 1 M48 770 800 750 670 620 722 720 5,0 20% 30% 40% 50% 60%

35 C66 700 330 740 930 730 686 690 4,8 cement

5% 580 660 610 12 M35 640 670 860 670 600 688 690 4,8 6% 620 770 39 M37 720 770 760 640 490 676 680 4,7 7% 27 M55C+ 720 870 540 530 620 656 660 4,6 8% 26 M55F+ 560 790 670 530 760 662 660 4,6 41 M55 550 590 780 640 710 654 650 4,5 Group 3 (M) Sand mix: 1/2 course + 1/2 fine 34 C56 500 660 970 530 480 628 630 4,3 20% 30% 40% 50% 60%19 C65 710 490 570 710 610 618 620 4,3

cement 5% 690 430 650 500

30 M55F+ 530 600 520 620 850 624 620 4,3 6% 590 760 730 37 M36C+ 600 660 610 440 810 624 620 4,3 7% 680 17 M65C+ 750 460 690 540 630 614 610 4,2 8% 720 36 M36 630 600 570 650 510 592 590 4,1 25 M45C+ 600 640 600 400 680 584 580 4,0 Group 4 (MF+) Sand mix: 1/3 course + 2/3 fine 7 C45 380 660 430 580 740 558 560 3,9 20% 30% 40% 50% 60%

40 M55C+ 710 490 660 550 390 560 560 3,9 cement

5% 770 660 480 38 M36F+ 570 660 470 540 450 538 540 3,7 6% 540 880 2 C28 480 580 640 470 400 514 510 3,5 7%

16 M65 400 560 500 480 570 502 500 3,4 8% 760 10 C25 420 450 610 590 380 490 490 3,4 31 M65F+ 510 300 450 640 490 478 480 3,3 Group 5 (F) Sand mix: 3/3 fine 4 C48 370 480 540 470 500 472 470 3,2 20% 30% 40% 50% 60%

29 F65 540 470 480 440 430 472 470 3,2 cement

5% 780 470 8 C46 420 480 500 490 430 464 460 3,2 6% 9 M45 330 210 460 620 540 432 430 3,0 7%

18 C55 300 340 450 440 440 394 390 2,7 8% 11 C26 290 450 360 300 300 340 340 2,3 5 C35 330 210 270 410 230 290 290 2,0

Crushing strength of CSEB in dry condition Tested by Bangladesh University of Engineering and Technology

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Crushing strength of CSEB in wet condition Tested by Bangladesh University of Engineering and Technology

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Crushing strength [psi] of 5 samples in WET condition

(after 24 hour immersion in water)

Rounded average crushing strength [psi] of 5 samples in WET condition by group type

Laboratory number

ID code of mix 1 2 3 4 5 Average

[psi]

Rounded average

[psi]

Rounded average [MPa]

20 M56F+ 200 330 260 280 310 276 280 1,9 Group 1 (C) Sand mix: 3/3 course 32 M46C+ 340 230 270 270 240 270 270 1,9 20% 30% 40% 50% 60%1 M48 250 250 170 250 240 232 230 1,6

cement 5%

33 M56 90 260 150 350 230 216 220 1,5 6% 3 C38 70 270 250 170 200 192 190 1,3 7%

28 F45 170 200 230 120 190 182 180 1,2 8% 190 13 M46 90 170 130 140 110 128 130 0,9 24 M45F+ 110 140 - 80 - 110 110 0,8 Group 2 (MC+) Sand mix: 2/3 course + 1/3 fine

20% 30% 40% 50% 60%

cement 5% 6% 270 7% 8%

Group 3 (M) Sand mix: 1/2 course + 1/2 fine

20% 30% 40% 50% 60%

cement 5% 6% 130 220 7% 8% 230

Group 4 (MF+) Sand mix: 1/3 course + 2/3 fine

20% 30% 40% 50% 60%

cement 5% 110 6% 280 7% 8%

Group 5 (F) Sand mix: 3/3 fine

20% 30% 40% 50% 60%

cement 5% 180 6% 7% 8%

Our pilot project on Compressed Stabilized Earth Blocks revealed that they are not suitable for large-scale production in Bangladesh for several reasons.

Unsuitable soil

High weight

Soil depletion

•  Only 10% cheaper Questionable cost advantage

Low water resistance

Inconsistent quality

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Soil Testing Report ATTACHEMENT

The following pages show the laboratory results of relevant soil samples collected in Shariatpur, Bangladesh. Soil samples collected in other regions of Bangladesh are not included in this report. The laboratory analysis consist of hydrometer analysis and sieve analysis. This report does not explain the testing procedure. Compiled on 4 November 2015 by Ava Mulla, Building Pioneers

For CSEB a well-graded soil should be used. Well-graded means an even representation of different grain sizes. A text book composition for CSEB is 15% gravel, 50% sand, 15% silt and 20% clay. The components of soil are defined as follows: gravel (> 2 mm), sand (0.06 - 2 mm), silt (0.002 - 0.06 mm) and clay (< 0.002 mm). The ideal soil composition could not be found in any soil sample extracted in Bangladesh. The samples either contain sufficient sand but insufficient clay, or sufficient clay but insufficient sand.

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#

Composition of soil sample

Sand [%]

Silt [%]

Clay [%] Type

1 6 86 8 Silt

2 54 45 1 Sandy loam

3 0.7 58.2 41.1 Silty clay

4 0.6 56.3 43.1 Silty clay

5 8 65 27 Silty loam

6 0.5 61.0 38.5 Silty clay loam

7 4 56 40 Silty clay

8 1.5 48.5 50.0 Silty clay

9 0.2 73.1 26.7 Silty clay loam

10 3.00 81.6 15.4 Silt loam

Soil Report for the Pilot Project on Compressed Stabilized Earth Blocks in Bangladesh

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Sample number

Place of extraction

GPS coordinates of extraction points

Laboratory*

Composition of soil sample

North East Sand [%]

0.06 to 2.0 mm

Silt [%] 0.002 to 0.06 mm

Clay [%] < 0.002

mm Type

1 Shariatpur - - BUET 6 86 8 Silt

2 Shariatpur - - BUET 54 45 1 Sandy loam

3 Shariatpur - - TUM 0.7 58.2 41.1 Silty clay

4 Shariatpur 23°09.176 90°21.490 TUM 0.6 56.3 43.1 Silty clay

5 Shariatpur 23°09.397 90°20.882 IL 8 65 27 Silty loam

6 Shariatpur 23°15.293 90°12.485 TUM 0.5 61.0 38.5 Silty clay loam

7 Shariatpur 23°15.293 90°12.485 IL 4 56 40 Silty clay

8 Shariatpur 23°15.259 90°12.683 TUM 1.5 48.5 50.0 Silty clay

9 Shariatpur - - TUM 0.2 73.1 26.7 Silty clay loam

10 Shariatpur - - TUM 3.00 81.6 15.4 Silt loam

* Laboratories assigned to soil sample testing:

BUET: Bangladesh University of Engineering and Technology in Dhaka, Bangladesh TUM: Technical University of Munich in Munich, Germany IL: In-house lab of the pilot project

Soil Report for the Pilot Project on Compressed Stabilized Earth Blocks in Bangladesh

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Pictures of the CSEB pilot production in Shariatpur, Bangladesh

ATTACHEMENT

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5

Leave for 2 days under plastic cover Cure for 26 days

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Compress the mix in a machine

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Mix soil, sand, 5-8% cement and water Dry the soil Crush the soil

The CSEB production process

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