[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

GSBN:Plastic bottles in bales

Hi Bruce,
Thanks for your details on the plastic bottle building. I take on board
your comment regarding cost in particular, and shall investigate

Kind regards
Brian Hodge

-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Bruce King
Sent: Thursday, 3 August 2006 11:07 AM
Subject: Re: GSBN:Leather Bales

On Aug 1, 2006, at 3:43 AM, brian wrote:

> Hi to all,
> I am unsure of the outcome of leather in bales, but it did prompt a
> question
> on my part. I have been contacted by an Aboriginal elder wanting to 
> build
> homes for his people in Broome Australia. The humidity is high. Too 
> high for
> Straw bale. I would be interested to hear if anyone has baled plastic
> bottles for building, as there is an abundance available. I would 
> think that
> a cement lime render would be best if it was feesable. Does anyone 
> have any
> suggestions?

Brian, a Colorado (USA) architect, Doug Eichelberger, has built some 
experimental structures with plastic bales, and local University 
students did some associated testing.

I wrote that up in some detail for the upcoming book, "Design of Straw 
Bale Buildings";  here it is:

2.2.2  Plastic and other baled materials

Jean Nielsen built an experimental load-bearing structure of paper 
bales at the University of Arizona some years ago, and others have 
experimented with baled paper, cardboard, and pine needles, but there 
have been no reports as yet of promising developments.

Architect/builder Doug Eichelberger is experimenting with baled plastic 
water bottles, and collaborating students at the University of Colorado 
conducted a cursory battery of tests from which the following comments 
are drawn.

Figure 2.2A

Plastic Bales	

photographs courtesy
Doug Eichelberger
and George Nez


Advances in technology or changes in economic conditions can affect a 
building material's viability, availability, and usage.  As an example, 
plastic is a petroleum product; thus its price follows the price of 
oil.  Today [2005] in the United States discarded water bottles have a 
recycled value of as much as $0.30 per pound, partly due to material 
value and partly due to labor and transportation costs.  These costs 
have risen exponentially in the past ten years, and in some cases this 
kind of plastic used for a foundation may cost as much as concrete.  
However, agencies such as The World Health Organization have noted the 
growing problem of plastic waste in developing countries.  This problem 
is hugely exacerbated after a war or natural catastrophe ravages an 
area, triggering an influx of food, water, and other aid in plastic 
bottles and packaging.  Could baled waste plastic be a shelter solution 
for developing countries? Plastic as a raw material has an extremely 
long life, is moisture- and decay-resistant, and is lightweight and 
strong.  The building technology is both simple and ancient: stacking 
blocks or bales of materials on top of each other to create walls.

Building a test structure is the best means of trying out a new 
material, both for its inherent properties and as a system. In the 
1990's Doug Eichelberger built the first permitted prototype, a 36 x 48 
foot [11 x 14.6 meters] barn, followed by two bale homes in the 
mountains of Colorado.   All of the structures were constructed with 
plastic bale foundations and difficult-to-recycle paper bale walls.

His current project, described here, uses bales of household plastic to 
create both foundation and wall systems.  The project starts with 
collecting the plastic bottles and baling them into building blocks. 
Previous projects had used large, heavy bales (1800 lbs. [816 kg.] 
each), requiring machines to move and stack.  This new process involves 
much smaller bales that can be moved and stacked by hand, much like 
straw bales.

In Eichelberger's current project, the large bales were broken down and 
rebaled on site.   The baler is small by industry standards (used 
balers like this are available all over North America for between 500 
and 2000 USD), was loaded manually, and the three-wire tie-off was also 
done by hand.  The resulting bales weighed about 40-45 lbs. [18 to 20 
kg.], their dimensions were approximately 30 x 24 x 16 inches [76 x 61 
x 41 cm], and they took about 15 minutes to make.

Despite the simplicity of the machine and process there were numerous 
variables.  The baler ram force is a constant, but the actual material 
amount varied, so, like straw bales, the bales could expand in length 
from 24 to as much as 30 inches.  The wires were hand-tied when the ram 
had the material in maximum compression;  when the ram was released, 
the bales then expanded to the wire tension.  That tension varied from 
person to person, and according to the time of day and an individual's 
fatigue level.  Eventually the project team devised a crude tool that 
maximized tension at a somewhat consistent rate.  Even with this 
improved process, however, a range of bale strengths, weights, and 
sizes were produced but manageable.

Stacking/ stabilization
Since plastic bales are unaffected by moisture they were used for the 
foundation, though the long-term durability of the wire ties is 
unknown.  The bales were simply placed in a rough trench and pushed as 
close together as possible.  The site slopes slightly, so the 
foundation varied from one to two bales deep.  Colored  plastic bales 
were used for the foundation, as they were rougher in shape.  Above 
grade, two different wall types were constructed: load-bearing (bales 
flat, 16 inches high) and infill or post-and-beam (bales vertical, 24 
inches high).

Due to the strength of the plastic and the confused orientation of the 
material in the bales, it was impossible to drive spikes through the 
assembly to gain stability. Also, the slick, slightly convex surface of 
the bales and the stiffness and memory of the bottles made tight 
stacking difficult.

Bale proportion also became a stacking complication.  A typical straw 
bale or adobe brick has a 2:1 dimensional ratio, making a running bond 
easy to accommodate.  The running bond creates a sort of lock to the 
bale courses.  The baler used created a more square bale which made a 
running bond and its locking qualities impossible.

The solution for all this was a panelization process using vertical 
stabilizers and a simple form of post-tensioning. Since internal spikes 
proved so difficult to install, #3 external vertical reinforcing bars 
were sunk into the ground on the outside of the bales and tied together 
at each bale course, creating a series of quasi-columns.  Next, poles 
were placed vertically at the end of each run of bales.  Wires were run 
horizontally and tied tight, pulling the panels of bales together to 
create a unified wall.  The next form of post-tensioning used a wood 
plate laid on top of the wall with wires tied over the plate from side 
to side and fastened at the bottom (as is often done with straw bale 
walls).  Through this process the walls were compressed vertically as 
much as 4 inches.  This system also allowed the top plate to be 
leveled.  These stabilization methods were used in both wall types, and 
appeared to greatly strengthen the walls prior to roof loading.

A simple roof structure was installed and finished to load the walls 
prior to finishing.  The above-mentioned top plate became the bearing 
point for 2x wood rafters on the load-bearing wall.  External wood 
columns and a wood beam carry the load on the opposing wall.  
Corrugated metal is the roofing material.  The structure was left open 
so that added load could be applied to test differential loading and 

One-inch stucco netting was fastened directly to the bale wires and 
tie-down wires using cage clips and hog rings.  Gaps between bales were 
filled with loose plastic bottles to reduce stucco thickness.  A cement 
stucco base coat was mixed using 1/3-inch pea gravel as filler for the 
first/ filler coat.  A typical one-coat topping was applied as a 

Lab testing
Testing on plastic bales was completed in the spring of 2005 at the 
University of Colorado1; results can be viewed and/or downloaded at 
<a  target="_blank" href="http://www.edc-cu.org/ppt/PlasticBales.pdf";>http://www.edc-cu.org/ppt/PlasticBales.pdf</a>. The bales showed a range of 
strengths as follows:
.  Compressive strength up to 5 psi [35 kN/m2] at strains between 0.15 
and 0.28
.  Modulus of elasticity of 30 psi  [207 kN/m2] +/-
.  Density of 4 to 10 pcf  [64 to 160 kg/m3]

Since the wall system required a panelization/post tension approach, 
further lab tests will be completed on bales configured in those 
conditions.  From those results structural design criteria can be 
established.  Further tests could evaluate a plastered bale wall's 
insulative qualities.

In urban areas of the industrialized world, large amounts of plastic 
are typically available from local recycle centers.  Depending on local 
collection processes, recycled plastic comes in three basic categories: 
  PET (Polyethylene Terephthalate; water and soda bottles, which have 
the most value), HDPE (High Density Polyethylene milk jugs of lesser 
value), and finally colored plastics which include detergent, juice, 
and some food product containers.  They typically are available in 
large bales, allowing transport of a greater amount of material in a 
small volume.  (PVC, or Polyvinylchloride, is at once among the most 
useful, ubiquitous, toxic, and nearly impossible-to-recycle plastics in 
the marketplace.)

Potential problems
Baled, recycled plastic poses several problems that limit their utility 
as construction materials:
. Variability in bottle sizes and strengths- Sizes ranging from two 
liter soda bottles to tiny prescription drug bottles make for highly 
heterogeneous bales;
. Lids-  Some bottles still have their lids while others don't;  
bottles with lids are harder to compress, and the lids make the bottles 
want to return to their original shape;
. Some bottles still contain some of their contents, making for 
potential insect or mold problems;
. Once plastic catches fire it is difficult to extinguish, and fumes 
emitted from plastics can be toxic.  Furthermore, some bottles contain 
volatile materials like oil or lighter fluid;
. The reliance on metal wire ties, particularly below grade, requires 
long-term protection from corrosion.

The test structure appears to be a success, as it is carrying load 
without distress.  The passage of a few years will reveal any 
freeze/thaw problems, differential movement, or other problems should 
they occur.

What is the appropriate use of waste plastic?  The high cost of plastic 
in the industrialized world may make baled plastic construction 
unpractical there. On the other hand, areas of war, poverty, tropical 
climate, or natural disaster that already have a surplus plastic 
problem are also places where the availability of material and labor, 
coupled with the need for simple shelter, creates an opportunity-or 
even need-for baled plastic construction.

Figure 2.2B

Plastic Bale

photographs courtesy
Doug Eichelberger
and George Nez

--- StripMime Report -- processed MIME parts ---
  text/plain (text body -- kept)