When strength and self-reliance meet
Jim Kendall and Hiew Peng Wong
30 දෙසැම්බර් 2019

While earth has been used as a building material since ancient times, the European Union-funded “Homes not Houses” project in Sri Lanka is tapping into such materials and appropriate construction technology for a long-term impact. By the end of the multi-year project, the project will enable 2,385 Sri Lankan families who have been affected by the decades-long conflict to build or repair their homes. Self-sufficiency is also encouraged through the use and production of locally sourced earth blocks and construction materials and other appropriate construction technologies.

Habitat for Humanity Sri Lanka is providing its technical expertise in implementing the project in 31 divisions across the eastern district of Batticaloa and the northern districts of Kilinochchi and Mullaitivu.

Habitat’s partner organization World Vision Lanka provides flanking measures such as general livelihood support for families and communities including vocational training in construction. World Vision’s role also involves training local community members in the use of appropriate building materials and methods, disaster risk reduction and financial literacy as well as forming and strengthening small and medium-sized enterprises.

Since the project’s launch in January 2016, a total number of 1,258 families have built or repaired their homes while the remaining 1,127 houses are in various stages of construction as of June 30, 2019.

Under a homeowner-driven approach, families can choose from three house designs, each for a  house measuring 51 square meters (550 square feet) in size. The designs allow the families to expand their homes in the future when they have available funds. The families have the choice of building their homes with appropriate construction materials such as compressed stabilized earth blocks, known as CSEBs, or with traditional materials like fired bricks and cement sand blocks. The project also promotes the use of other appropriate construction technologies that have a lower environmental impact, are more resource-efficient, or perform better in the local climate than traditional technologies.

Yard in Batticaloa that produces compressed stabilized earth blocks
Yard in Vilavettuvan village, Manmunai West divisional secretariat, Batticaloa district, that is managed by Habitat for Humanity Sri Lanka’s partner organization World Vision Lanka. Workers at the yard produce compressed stabilized earth blocks that are used in some of the homes built under the European Union-funded “Homes not Houses” project in Sri Lanka.

The use of appropriate materials and technologies not only reduces harmful emissions and waste but also boosts the local economy. More livelihood opportunities can be made available to local community members including future Habitat homeowners who are trained in the technologies and production of associated building materials. In addition, the cultural practices and aspirations of the local communities are taken into account. It is expected that around 40 percent of the homes in the “Homes not Houses” project will be built using appropriate technologies and materials.

A feasibility study published by the European Union has cited CSEBs as a low-carbon, low embodied energy solution for sustainable development. Other researchers (Riza et al, 2011[1]) have listed the following advantages of using CSEBs:

It increases the utilization of local material and reduces the transportation cost as the production is in situ, making quality housing available to more people, and boosting the local economy rather than spending for imported materials.

  1. Good strength, insulation and thermal properties.

  2. Less carbon emission and embodied energy in the production phase.

  3. Resultant low levels of waste can easily be disposed of with no direct environmental pollution during the life cycle.

  4. Earth-based blocks also have the ability to absorb atmospheric moisture and create a healthy environment inside a building for its occupants.

Habitat Sri Lanka’s partner organization, World Vision Lanka, manages the yard in the east that produces the CSEBs that are used in the “Homes not Houses” project. The yard is located in Vilavettuvan village, Manmunai West divisional secretariat, Batticaloa district. Another three  yards have been set up in Kilinochchi and Mullaitivu districts in the north that are run by local organizations Project for Youth, LEADS and SN Enterprise under the local Rural Development Society.

World Vision Lanka has obtained government permission to extract raw soil from a local reservoir. At the yard, the soil is put through a crushing machine to produce the particles, each between 1 and 3 millimeters in size. With one cubic meter of soil, about 200 CSEBs can be cast, according to Nandakumar Amalan, former World Vision Lanka’s project coordinator who oversaw the yard’s operations.

A worker operating the press to produce compressed stabilized earth blocks in Batticaloa yard
A worker at the yard producing compressed stabilized earth blocks in Batticaloa

The sand and gravel content for the CSEBs should be more than 65 percent while the silt and clay content should be less than 35 percent to achieve the required strength and durability. The ratio of cement by volume is between 5 and 7 percent.

Using a manually operated press, low-skilled workers can produce between 800 and 850 CSEBs a day. There is also an automatic press that yields around 1,700 CSEBs a day. About 4,500 CSEBs are required to build a 51-square-meter home.

After being cast, the CSEBs are covered with plastic sheets and kept in the shade for two days by which time the blocks will have gained about 75 percent of their strength. Then the blocks are moved outdoor where they are covered in burlap and cured with water about three times a day for the remaining 28 days.

Saunthalathevy started working in the CSEB yard in April 2017 after 10 days of training. She has begun laying the foundation for her new home that would be built with CSEBs. “During the training, I was very happy. The blocks looked very nice and they have good strength,” says Saunthalathevy. She revealed that during the training, she dropped the blocks on purpose to test the strength. “My wish is that job opportunities will increase in this village as there are so many people without jobs.

The strengths of CSEBs are also recognized by local government leaders and the local masons who are involved in the “Homes not Houses” project. “Compressed stabilized earth blocks reduce environmental pollution and are good for the environment. As soil is available in this area, local resources are being used,” says S. Gopalakrishnan, former ‘grama niladari’ or village officer, Karaveddy, Vavunatheevu divisional secretariat. He shared his observation after visiting a model house built with CSEBs in Batticaloa district. “The house is very cool inside.”

Fair faced tool for laying mortar
During a training session, a local mason used a local tool in laying mortar to demonstrate the fair faced technique. Photo: Habitat for Humanity International.

Local mason Supramaniam Puthalvan has built 18 homes including his own home with CSEBs. He likes the regular size and shape of CSEBs for the ease of building walls compared to local fired bricks. Fellow mason Karunan Ramraj remarks: “With compressed stabilized earth blocks, they look nice even without plastering. The work is very neat.”

To date, Habitat and World Vision have trained more than 400 local masons and workers using appropriate construction technology and materials.

In northern Sri Lanka, a few homes have been built with earth concrete blocks. ECBs are made with a mix of earth and cement with the ratio of the cement varying between 5 and 8 percent depending on the type and the size of gravel particles. The ECBs are noted for being strong and can be used in place of conventional fired bricks. Yogeswary who has built her home with ECBs  is impressed with the blocks’ strength as well as thermal comfort.

With a 14-million-euro grant from the European Union, Habitat Sri Lanka is also promoting innovative appropriate construction technologies in the “Homes not Houses” project. The “fair faced” masonry technique uses uniformly cast blocks with pointed mortar joints. To achieve uniform thickness of the horizontal and vertical mortar joints in between blocks, a locally made mortar-laying guide tool is used.

The “fair faced” technique is an eco-friendly and more cost-effective alternative to the regular process of plastering walls because less sand, cement and skilled labor are used. The resultant wall is strong due to the proper bond pattern and vertical alignment. Walls that are built using the “fair faced” technique are aesthetically pleasing with little or no plastering.

The “Homes not Houses” project also features other alternative technologies such as filler slab, rat trap bond and ferrocement. Filler slabs and ferrocement slabs are used in some of the homes in northern Sri Lanka such as that of Yogeswary.

Home in Sri Lanka that is built with fair faced masonry technique
(From left) Lingakanthan and his wife Kohila with their child Yashwini in front of their home that has walls built with the fair faced technique. The family lives in Tharmapuram West village, Kandawalai divisional secretariat, Kilinochchi, northern Sri Lanka. Photo: Habitat for Humanity International/Kangatharan Dinushanth.

Filler slabs are supported, low-cost concrete slabs that are used in ceilings or kitchen countertops for short spans up to 3.6 meters. Concrete in the tension area of the slab cross section is replaced with a much cheaper filler material that is durable but less dense. Discarded roofing tiles and clay pots can be recycled as filler materials that save cost and provide thermal comfort. As the filler slab weighs less than a concrete slab, it reduces the need for steel reinforcement. The filler material is arranged in such a way that the filler slab looks aesthetically pleasing.

Ferrocement precast slabs or panels are lightweight, relatively cost-effective structures that are  often used for elements not requiring high strength such as a kitchen countertop, a non-load bearing wall or roof. Cement and sand are mixed to produce a rich mortar mixture that is reinforced with layers of chicken wire. A ferrocement slab should have a thickness of at least 2.5 centimeters and, if not supported on all sides, it should have beams with a reinforcement bar built into those sides.

Rat trap is a type of masonry bond in which the bricks are laid on edge such that the shiner and rowlock are visible on the face of the wall. The thickness of the wall is maintained at the width of two bricks. This gives the wall an internal cavity bridged by a rowlock. Thus, the use of materials such as bricks and mortar can be significantly reduced. The pocket of air between the inner and outer faces of the wall helps to maintain thermal comfort inside the building.

Other alternative practices include precast door and window frames that are of a higher quality than similarly priced but lower grade timber favored by some families. For the floor concrete, coarse aggregate can be substituted with hard, durable building debris by up to 50 percent. Masons can then trowel a smooth top finish for the floor.

At the official ground breaking ceremony in February 2017, Tung-Laï Margue, the ambassador to Sri Lanka and the Maldives for the delegation of the European Union, expressed his hope that returnee families gain not only homes and livelihoods but also the necessary support to rebuild their lives and create a better future.

Through the promotion and use of appropriate construction materials and technologies, Habitat Sri Lanka and World Vision Lanka are enabling conflict-affected families to have the strength to stand on their own and build self-reliance to create a better future.


[1] Riza, Fetra, Abdul Rahman, Ismail and Mujahid Ahmad Zaidi, Ahmad. “A brief review of Compressed Stabilized Earth Brick (CSEB).” CSSR 2010 – 2010 International Conference on Science and Social Research, 2011, https://www.researchgate.net/publication/224238871_A_brief_review_of_Compressed_Stabilized_Earth_Brick_CSEB

 

Jim Kendall and Hiew Peng Wong
30 දෙසැම්බර් 2019
Jim Kendall, a registered architect, is the appropriate construction technology specialist for Asia-Pacific with Habitat for Humanity International. Hiew Peng Wong takes on an editorial role as a manager with Habitat’s Asia-Pacific communications team. The technical team of Habitat for Humanity Sri Lanka also contributed to this article.

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