Plastics or PET, though indispensable part of our lives, are non-biodegradable substances composed of toxic chemicals, that pollute during both production and disposal-especially by burning or land filling. Plastic waste comprises of approximately 11% of the content landfills, causing serious environmental consequences.With approximately 100 million tons of plastic being produced each year, eco-friendly architectural principles should be incorporated into engineering buildings.

Polyethylene Terephthalate or PET (C10H8O4) has a composition of polyester of Terephthalic acid and ethylene glycol. It is white or light cream material; density of 1.3322 g/cm3; melting Point of 225 – 2650C ; is insoluble in water; is heat resistant and chemically stable. PET is resistant to acid, base, some solvents, oils, fats, difficult to melt and transparent. It is used mainly for domestic purposes. Research and Development related to the use of PET for commercial plastic bottles application began in the late 1960s, intensifying during the period 1971-1975.

Approximately 15 to 27% is actually recycled annually. The main problems of recycling plastic through the melting and remolding are the highly toxic chemicals; degrades in quality and necessitates the production of new plastic thus uneconomical; the process is also labor intensive with high cost of implementation. Disposing non-biodegradable plastic with an insolubility about 300 years makes it a significant environmental pollutant. 

The history of Bottle Walled housing can be seen in William. F. Peck’s glass bottles house built in 1902 in Tonopah, Nevada using 10,000 beer bottles which were 90% alcohol and 10% opium.  In the 1960s, Heineken constructed the Heineken World Bottle or W.OBO -a structure from rectangular shaped beer bottles that could double as bricks for affordable housing. Concerned with the lack of affordable building materials and the inadequate living conditions plaguing Curaçao’s lower-class, Heineken made about 1000 WOBOs and even constructed a prototype home. In Uganda, Cayuga District in 2010, the Butakoola Village Association for Development (BUVAD) conducted a survey that revealed that due to the presence of waste plastic in the soil, farmers in Kayunga were experiencing low crop yields. In Nigeria, the first plastic bottles house was constructed in the village of Yelwa in Nigeria by Andreas Forese. Plastic bottles were bound together using strings and rendered/plastered on. Others are in Honduras, Bolivia and South Africa.

Materials required are plastic bottles, sand and cement with a sand to cement mix of 3:1. Bottle walls are extremely versatile and endures long periods in all climates. The most appropriate bottle size is 500 ml size- it’s quite difficult to manually compact aggregate into a bottle of larger size. It is preferred that the packing material is of non-corrosive plastic form or dry soil. Degradable materials decompose and as a result compromise the structural integrity of the structure. 

A metal rod is used to compact the aggregate. It should be of diameter twelve to sixteen millimeters and three fifty to five hundred millimeters length to ensure firm grip on it to enable maneuverability, reach the bottom of the bottle and the inner edges .Preference should be on the use of bottles with similar dimensions of 8.71” height and 2.62” width (typical 500ml bottle). Bottles should be densely stuffed to discourage deformation under intense pressure of 10 to 15 kilo-Newtons from both compressional and tensile stress. The bottle brick should weigh no less than 220 grams after the packing process. The mass per unit volume lays an important role in the strength of bottle bricks. Significant quality of bottle brick can be observed from touch. 

Void detection can be done by lightly banging the top end of the brick directly against a hard horizontal surface. Voids are detected by appearance of air spaces (seen as thin horizontal lines) in the soil aggregate. One in every ten bricks made could be tested using this method as the sampling of every single bottle brick would be very costly and time consuming. Materials uses for Bottle wall masonry construction are fine soil, plastic PET bottles, cement, nylon rope and water.

Bottle Brick technology can alleviate the short supply of affordable housing units to the low and middle income groups in Kenya. Secondary data shows construction of such housing units can create employment opportunities for youth; reduces plastic waste nuisance; and provide an avenue for achievement of other Sustainable Development Goals. Although bottle bricks are a viable alternative building technology, there has been little direct effort by the Government to meet the housing deficit by increasing supply of units; as well as poor utilization of locally available materials in the construction of housing industry.

The main challenges for standard housing is the cost of land and materials used. The upper class secures credit to offset these high costs.  However, the low income class, is unable to secure loans resulting in use of unconventional building techniques and materials ; use of hazardous, overcrowded spaces (such as near or under power lines or road reserves) posing risks to the occupants .This is coupled by limited research on low cost housing building material. Consequently, only an estimated 6,000 units (20%) of all houses are produced catering for this group, with only 23% of the housing demand being met. The existing gap where the demand for low-income households is 48% of the total new houses required – since more than 80% of new houses constructed are for high and upper middle-income earners.

The Bottle Brick Housing will create employment. According to a Government survey in 2009, unemployment stood at 40%.  Goal 8 of the Sustainable Development Goals requires member states promote full and productive employment and work for all. Goal 8 of the Sustainable Development Goals requires member states promote full and productive employment and work for all. 

In constructing a house by plastic bottles used for the walls, ceiling joist and concrete column saves 45% of the final cost. Specific component costs (of cost shows that the use of local manpower in making bottle bricks can lead to cost reduction up to 75%. PET bottle bricks are an alternative building technology that should be promoted especially because whereas labour is cheap in Kenya, conventional building materials are expensive. This dynamic makes it even more preferable.

Non brittle characteristics of bottle bricks reduce construction waste due to breakage in comparison to bricks. Bottle bricks absorb abrupt shock loads which enhances performance against unexpected load. Each bottle brick’s resistance against the load is twenty times higher compared to brick. As far as insulation of bottle bricks goes, filling each bottle by three layers where the front and back of the bottle are filled by sand or compact gravel while the middle of bottle should be filled by cork/wood articles. The plastic bottles can be re-used even after the wall has been brought down. The stacking procedure used in the wall erection is repetitive and thus easy to master. 

PET bottles that are not recycled end up in landfills or as litter, and they take approximately 1000 years to bio-degrade .Reusing or recycling mitigates negative environmental impacts related to it. Goal 11 proposes creation of sustainable and resilient settlements. Goal 15 speaks of the protection of eco systems and bio diversity. The use of bottle bricks will reduce Green House Gas emissions during production of precast building blocks and substantially increase the chances of higher forest cover. Also, the pollution menace of plastic bottles can be reduced since the source of the building materials-landfills- directly reduces pollution without need for providing for remedial measures to the environment.  

The term “LEED” stands for Leadership in Energy and Environmental Design, a program administered by the U.S. Green Building Council, a private, non-profit organization. These rating systems are market driven, voluntary and consensus-based designed for new and existing buildings based on accepted energy and environmental principles. Each rating system is organized into various environmental categories among them Materials and Resources and Innovation in Design. 

These systems indeed dictate what project can be considered ‘green’. They should, for instance: comply to environmental laws; reasonably use the site boundary; a minimum floor area of 1,000 square feet; a specific minimum building area to site area ratio (gross floor area must be no less than 2% of the gross land area) among others. 

Population explosion, rapid urbanization, poverty spread and escalating of costs of providing housing are direct causes of deteriorating housing conditions and a dwindling supply of units. The direct cause is the economic model guiding the housing policy. The Kenya Housing Policy promotes low cost building materials and construction techniques. The bottle wall project will achieve sustainable development by tackling climate change; realizing financial savings (on cost of building materials); and the increase of working class housing supply (which is significant to the alleviation of poverty in Kenya). These goals cut across elements of the National Housing Policy. The housing inputs in the Policy are building materials, research and financial resources.  Alleviation of poverty will be by the creation of a bottle brick making industry such as small and medium scale enterprises that engage in the production of approved alternative building materials. 

Rapid urbanization; high rate of rural–urban migration; economic decline; high poverty levels; limited access to finance and high cost of credit( a key element of bourgeois economy); escalating housing costs and prices; limited research on low cost housing building materials and construction technologies; high infrastructural standards(outdated & rigid building code) stringent planning regulations; and high costs of building materials, have led to the shortfall and dilapidated state of housing and human settlements.

The recommendations thus stand as:

a. Collaboration by all willing and able for the facilitation of pilot projects.

b. The creation of a Bottle Brick construction sub industry in order to create employment.

c. A change from current market- oriented housing policy implementation strategy to one of planned budgetary allocation and direct involvement by the state for housing. 

Recommendations call for the technical and financial facilitation of experimental pilot projects on Bottle Brick walling; enhanced community involvement in the areas experiencing housing unit deficits as well as PET plastic pollution nuisance; support of small scale construction activities utilizing bottle brick technology and change in current housing policy implementation strategy.

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