“Geopolymer cements offer an alternative to, and potential replacement for, ordinary Portland cement (OPC). Geopolymer technology also has the potential to reduce global greenhouse emissions caused by OPC production. There is already a considerable amount of work and research conducted on geopolymers in the past decades, and it is now possible to implement this technology commercially. However, to ensure that geopolymer becomes commercially available and able to be used in the world, further understanding of its ability to provide durable and long lasting materials is required. One main property which is still relatively unexplored compared to other properties is its shrinkage properties. The objective of this thesis is therefore to examine the shrinkage of geopolymers and factors which might influence it.

The factors which influence geopolymer strength were investigated as being the factors which may influence shrinkage. The selection of the activating solution is an important factor in forming the final product of a geopolymer. Activating solution SiO2/Na2O ratio is determined to be an important influence on the shrinkage of geopolymer. SEM images of the samples enable observation of the sample topology and microstructure. An important observation was the existence of a ‘knee point’ which also occurs in OPC shrinkage. The ‘knee point’ is the point where the shrinkage goes from rapid shrinkage to slow shrinkage. From SEMs it is noted that the samples past the knee point are shown to have a smoother topology which means it is more reacted.”

Source: Melbourne University Library

Floating Cities

I prefer low tech, low cost approaches, but it’s fun to consider larger scale solutions and what could happen in the future.

This paper presents the findings of an experimental investigation to study the effect of alkali content in geopolymer mortar specimens exposed to sulphuric acid. Geopolymer mortar specimens were manufactured from Class F fly ash by activation with a mixture of sodium hydroxide and sodium silicate solution containing 5% to 8% Na2O. Durability of specimens were assessed by immersing them in 10% sulphuric acid solution and periodically monitoring surface deterioration and depth of dealkalization, changes in weight and residual compressive strength over a period of 24 weeks. Microstructural changes in the specimens were studied with Scanning electron microscopy (SEM) and EDAX. Alkali content in the activator solution significantly affects the durability of fly ash based geopolymer mortars in sulphuric acid. Specimens manufactured with higher alkali content performed better than those manufactured with lower alkali content. After 24 weeks in sulphuric acid, specimen with 8% alkali still recorded a residual strength as high as 55%.

Source: Waset.org

Seasteading Part 2

A house boat similar to this but with a shallow rooftop garden and solar panels would provide a very livable structure for a mobile, adventurous lifestyle.

A house boat similar to this but with a shallow rooftop garden and solar panels would provide a very livable structure for a mobile, adventurous lifestyle.

You’ve got to love the Internet. You can find just about anything with enough time and effort. I wrote about my seasteading idea the other day. This got me wondering about the best places to seastead. A quick search turned up world maps of Tracks and Intensity of All Tropical Storms and Wave Heights at Seasteading.org. This is a great site. They seem to have all the answers on seasteading.

A quick search for house boats located the photo above on Wiki. A locally made boat like this might be quite reasonable in cost.

Be sure to take a look at The World of Ferro-cement Boats. Their website says “Ferro-cement boats built before 1855 are still in existence and at least one is still afloat. It is the cheapest and easiest form of construction for boats over 25 ft.” They have lots of information that will likely prove invaluable – building directions, galleries, a forum, and plans and boats for sale.

Floating Dirt Seastead is another good site with lots of interesting ideas for do-it-yourself seasteaders on a tight budget.

California Concrete Canoe, a contest for engineering students, is another good resource.

How many reasons do you need to live or vacation in a tropical paradise like Tahiti?

How many reasons do you need to live or vacation in a tropical paradise like Tahiti?

Image source: About.com

I’m currently researching the feasibility of building floating structures made of geopolymer. Most of the designs/plans I’ve read about so far are for expensive floating cities and luxury rentals. I’m still looking for a practical DIY model for the average guy. One possibility is building a raft that can be towed with a boat. The raft would provide food production (floating garden), potable water storage and additional living space at fairly low cost.

This seasteading concept is just an interesting idea at this time, but it’s worth contemplating because there are lots of benefits. Here are a few structural considerations:
– Build the raft in a safe area with very low risk of piracy, hurricanes, storms and tsunamis. You will need to collect rainwater and/or have access to fresh water.
– Design possibility #1: build modular, geopolymer or foamed geopolymer blocks that are joined together to create the desired size. Hollow core ferrocement blocks could be cast in a reusable form. The core could be filled with sealed, recycled plastic bottles or foam.
– Design possibility #2: use recycled barrels to make something similar to design #1 by casting foamed geopolymer around the barrel. Fill the barrel with recycled plastic bottles or foam. Attach strips of rubber tires between barrels where they contact each other and the deck. Add more ferrocement barrels at any time to expand the size. Build a deck on top with local wood or possibly plastic lumber. http://en.wikipedia.org/wiki/Plastic_lumber
– Design possibility #3: Retrofit a houseboat with a rooftop garden.

Why choose seasteading? The links below go into all the details. Here are a few benefits described at Seasteading – Homesteading the High Seas.
“Why would anyone want to colonize the ocean surface? There are a number of reasons — adventure, religious freedom, tax avoidance, trying out new forms of government, etc. Of the ones listed, tax avoidance is my pick as the most powerful motivator for the development of sea surface colonization technology.”

Floating Concrete Shell Structures
Seasteading Institute
Seasteading Forum

Geopolymer concrete block made with waste coal fly ash.

Geopolymer concrete block made with waste coal fly ash.

Project Type:
urban planning design strategy, architecture

Project Mission/Goal:
increase awareness of the environment and/or address climate change

Project Description:
The coal combustion process produces one of the largest unregulated solid wastes in the United States. Although in recent years a growing percentage of the airborne particulates (‘fly ash’) found uses as a filler in the cement industry, recent changes in EPA regulations aimed at reducing greenhouse gasses (GHG) emissions has resulted in most of the 70 million tons of fly ash produced annually in the US becoming unusable for current construction processes due to high levels of unburned carbon, ammonia and/or other impurities. Furthermore, the significant costs associated with transporting and land filling solids derived from coal combustion could be further increased due to liabilities associated with the eventual leaching of harmful levels of aluminum, chloride, iron, manganese and toxic levels of arsenic, nickel, lead, copper and zinc into subterranean water tables. Thus, the development of innovative technologies for converting tens of million tons of combustion bi-products annually into useful products is an urgent need.

What is Geopolymer:
-A hardened cementitious paste made from fly ash without Portland cement. It has greater compressive and tensile strengths, high strength gain rate, lower porosity and permeability, and greatly enhanced resistance to chemical attack compared with ordinary Portland cement (OPC) concrete. It combines waste products into a useful product, conserving landfill space and promoting sustainability, and compared with Portland cement, it features a 90% or greater reduction in carbon dioxide emission.
-A solution of sodium hydroxide and potassium hydroxide (waste products from the chemical and petrochemical industries) must be prepared separately, then added to the liquid commercial sodium silicate; this solution may then be added to the powdered fly ash (waste product from coal and bio fuel combustion) in the same way as water is added for Portland cement.

Source: Open Architecture Network

“The Cold Climate Housing Research Center (CCHRC) is performing a high level analysis of the local market potential for geopolymer cements. The analysis includes an assessment of available local materials, potential of local product manufacturing, and potential economic feasibility. This is a sister project to the Magnesium Phosphate Cement Testing and Application project funded by Alaska Housing Finance Corporation (AHFC).

CCHRC is developing geopolymer cement formulas that use local raw materials and analyzing the market potential for the product in Alaska.

Geopolymer cements use waste materials as a binder and are stronger and more sustainable than conventional Portland cements. CCHRC has studied more than 600 recipes of geopolymers made with use fly ash, a byproduct of coal combustion, from local power plants. Researchers are working to develop a product that is strong, cost-competitive and cures at the right time and temperature to be used commercially. Geopolymers are already commercially available elsewhere in the world.

Creating cement requires water, an alumina silicate material, and an alkali activator such as sodium hydroxide and sodium silicate. Nearly any product made with concrete can be made with geopolymer cements. The applications are endless for buildings, transportation, and many other areas.”

Source: Cold Climate Housing Research Center