Autoclaved Aerated Concrete (AAC)
The Wonders of AerBlock is an article written by Kelly Hart about AAC and how Michael Baron discovered and promotes its use.
Autoclaved Aerated Concrete - Innovation and Development (Book + CD-ROM) by Mukesh C. Limbachiya, John J. Roberts, 2005. Autoclaved Aerated Concrete (AAC), known in the UK as Aircrete, has gained world-wide recognition as a high quality, innovative construction material which has been extensively used in a wide range of residential, commercial and industrial buildings. Innovations and developments in AAC production and usage, forms part of the Proceedings of the two-day International Conference organised by the Concrete and Masonry Research Group at Kingston University, held in September 2005. The Conference deals with issues such as raw materials, manufacturing techniques and product characteristics that satisfy ever more demanding energy, design, structural and environmental requirements for sustainable development.
Autoclaved Aerated Concrete - Properties, Testing and Design by Rilem Tech Comm, 1993. This is a comprehensive guide to autoclaved aerated concrete (AAC) for designers, specifiers, users and manufacturers. It provides a model code of practice for the structural use of AAC and provides designers with a complete guide to the structural use of AAC in structural applications in building. Here are some links related to this material, sometimes called AAC: | ||||||||
They give a "thermal conductance" value of 0.759 BTU-in/hr-ft 2-° F, which translates to about R-1.4/in., so the 5" thick block would be about R-7, but this can be misleading, since the overall performance of the wall system may measure much better than this. Using the IECC mass adjusted tables you get an R-18 equivalent in Houston, Texas, where the manufacturing plant is. You can learn more about this product by visiting crescoconcrete.com. |
This material was first brought to my attention by a local builder who has become a distributor for it and is building with it locally. It is really pretty fascinating stuff, with some great characteristics. In a way it is like man-made pumice, in that it is masonry, but is still rather lightweight. It is highly insulating and completely fireproof. I once held a one-inch thick piece of it it in my hand while a blow torch heated the opposite side, and I could barely feel it get warm! It can be cut with any carbide-tipped tool into very precise shapes, then the blocks can be "glued" together with ordinary masonry tile products. Precut blocks are available that have channels in them for standard rebar bond beam applications.This material has been used for buildings in Europe for a couple of decades, but is just now being tried in the United States. It is fairly expensive, but I would expect it to be extremely durable and create well-insulated and attractive structures. Interior and exterior finishes can be spayed on to provide a uniform, durable and colored surface. It has occurred to me that this stuff could be precut into "kit houses" that were architecturally intricate and beautiful, and would just need to be assembled by numbers.
Liteblok™ is an aerated, precision molded concrete block. Unlike autoclaved aerated concrete, it is not autoclaved. Rather, a non-toxic foaming agent is introduced to create a closed structure of discrete air pockets. The blocks are laid without mortar and are interlocking and lightweight allowing for significant savings in construction time and cost. Applications include residential and commercial construction, fences and retaining walls.
Thermoplan systems use Ziegel blocks with a thin bed of mortar, to provide a breathing wall construction system. When combined with woodfibre board they can form a thermally and acoustically high performance shell. The Ziegel blocks come as part of a full load-bearing external and internal wall masonry system, and combine high thermal performance with robustness, speed of build and a breathing wall design. Because of all the trapped air and the thickness of the walls, these blocks provide reasonable insulation, while at the same time do provide some degree of interior thermal mass for maintaining constant interior temperatures. This is an unusual combination of these two factors in a single wall system. See www.burdensenvironmental.com or www.natural-building.co.uk for information for this innovative system. |
| Wood-fibre boards are rigid insulation boards made from wood chippings and are available in Europe. They are manufactured from the by-products of sawmills. Softwood chippings are pulped and mixed with water and mechanically pressed into boards, typically 20mm thick. Typically a binder of natural tree resin is used. Various boards are available for different applications: insulating sarking board for roof constructions; below-screed flooring board for both thermal and acoustic insulation; internal and external insulating lining boards.
See www.woodsinsulation.co.uk ; www.constructionresources.com ; burdensenvironmental.com ; www.greenspec.co.uk ; www.lime.org.uk for more information. |
| Conics Conics with plywood: CONICS is a radical roof system design that reaches for the ideal of a minimal architectural form that is both functional and inspirational. Made entirely of a 1/2 inch plywood skin, CONICS mimic the natural landforms of ancient mountain ranges which approximate an interlocking network of regular and inverted cone segments. Built to last, these mountain ranges have evolved into this cone-based geometry because it maximizes resistance to earthquakes, wind, water, ice, and other forces of nature. CONICS borrows this geometry to create a minimal system where the plywood acts as structure, sheathing and roofing. CONICS are made entirely of tiled 4'x4' plywood sheets that are simply attached (no pre-bending required), The resulting architectural form is both concave and convex, creating interior spaces that undulate in ways no other architecture has achieved. CONICS can be constructed with unskilled labor very quickly and the cost for CONICS is as low as $2.00 (US) per square foot (materials only). A multimedia CD-ROM is in the works that will include all the details of CONICS construction, the entirety of both patents for CONICS, construction plans, photographs, video segments, etc. Purchase of the CD-ROM will provide a license to build 10,000 sq. ft. of these unusual structures. Pre-release sales of the CONICS CD-ROM are available for $49.00. Visit Chuck Henderson's website, fishrock.com/conics, to learn more about this. Conics with metal: Avi Rotem is a civil engineer, born in Chicago and living in Israel, and his hobby for the last few decades has been devising building systems. He believes that he has a system here that is both very energy efficient, quick and inexpensive to build and pleasing to most people's eye. The system in made of many ideas [some old and some new] which have been combined. He has no desire to benefit financially from anyone's use of these ideas and hopes that he has not infringed on anyone's patents or rights. He believes that this type of system could help needy people in many areas of the world, and he is willing to donate his time toward this end. Here is a summary of the system along with pictures of a 1:15 model he made. |
| Domespace is what this French company calls their unique, rotating domes that can turn to face the sun as it traverses the sky. These domes have been built in many countries. Although they can be very energy efficient, I wouldn't exactly call them "ecological", since they are made almost entirely of wood and are based on a fairly high-tech concept. You can find out more about them by going to their website: www.domespace.com . |
An all-natural magnesium oxide cold ceramic cement based building panel that can replace drywall, OSB and plywood. See www.geoswan.com for more information. Here is a very informative article about Magnesium Oxide which is used as a cement in this product, comparing it to Portland cement and pointing out its many benefits. |
| Fire-proof bricks made from compressed earth, fly ash and recycled wood have an interlocking pattern for easy assembly. More information at: environmental.builderspot.com . |
| Building blocks made out of recycled fly ash and wood fiber. More information available at superhomebuilders.com . woodbrik an article about a product made from recycled wood fiber and fly ash. |
| endurablock.com features specially formed concrete blocks which can receive insulated inserts. These are drystacked and then surface bonded, so the construction goes fast. |
| earthcomegablock.com manufactures machines to produce gigantic compressed earth blocks for construction, requiring heavy equipment to lift into place. |
cavitywall.net I am impressed with the sophistication and simplicity of this patented system; it appears very well thought out and quite practical, utilizing precast lightweight concrete hollow blocks that require no mortar to assemble. I have often thought that hollow walls is an appropriate way to minimize material use and maximize insulative values. The designer says "I firmly believe that I can build for under $50/sf. The one step finished wall and stay in place form saves a lot. The truss type action of having the wall face plane given the depth of the cavity connection concentrates the mass as an I-beam as far as possible from the neutral axis, creating a much higher wall stiffness with a minimum amount of material. The erection is quite simple too, except for the forming of the ceiling slab. I think a scaffold system supporting interior reusable trusses spaced on the width of the stay in place lightweight pavers may work well." |
| Inflatable Canvas/Concrete Shelter This article describes a unique concept for creating almost instantaneous shelters with cement-impregnated inflatable canvas: wired.com/news |
| world-science.net This article discribes a unique approach to creating housing by spraying a ceramic-like material on a stryrofoam or other naturally woven frame material to create a solid structure. grancrete.net is the website of the company itself. gigacrete.com describes a cementious panelized product that utilizes various waste materials to manufactrure. Here is a very informative article about Magnesium Oxide which is used as a cement in these products, comparing it to Portland cement and pointing out its many benefits. |
| by Simon Stanfield Kelly Hart asked me to write a paragraph or two on the subject of making cementitious building materials right at project sites. The benefits of doing this, especially using special or native materials, are so enormous, I really don't know where to begin, but here goes …
A volumetric or continuous mix unit on site can resolve this dilemma. These are self-contained concrete production systems mounted on a skid or truck chassis. Some larger capacity units have their own power and are mounted on fifth wheel semi-trailers. In this case, a truck can simply drop the trailer in place, unhook and then ideally hook up a dump trailer to haul in materials. Cement can be supplied in all cases with a portable bulk cement tank, super bags or even paper bags. Water is often available at the jobsite from a well, stream or pond, but should be potable to avoid a lot of undesirable organic matter permeating tanks, pumps, valves, gauges and the mix itself. Depending on the materials being blended (the mixer part of these systems resembles nothing so much as a kitchen blender), most can be trucked in and loaded with a skid steer or front-end loader.A volumetric (thus named because it proportions by volume rather than weight) concrete plant occupies a footprint the size of a truck parking space. An area on each side is necessary to access the holding bins with a loading device. Power can be an integrated diesel engine, truck engine or electric motor. The system is powered hydraulically, so it's simply a matter of powering the hydraulic pump. These things will blend anything. I have personally set up machines to homogenize shredded wood, light weight aggregate, heavy weight aggregate, Styrofoam beads, just sand, just stone, polymers, fiberglass, foam, dirt, shale and a hundred other things. Constructing on site with native materials is a grossly underutilized application of this equipment. (Much of Interstate 80, "Mainstreet USA," was built this way with materials excavated from the environment beside the road grade. Communities have capitalized on this by establishing parks and wildlife sanctuaries in the resulting wetlands.)ASTM Specification C-685 governs the manufacture and usage of volumetric equipment. It must conform to certain standards and be able to proportion materials with less than 1% direct variation. This is less variation than most weight-batch systems exhibit. Usually a belt or chain drag system pulls the materials being blended through calibrated strike-off gates. Special materials can be added as liquids through flow meters, or very low dose vane feeders as powdered solids. Foam can be injected at the mixer throat from a foam generator. Reinforcing fiber can be added at the most advantageous point. Cement, or the binder, is added with water and admixtures where all materials are gathered into a fully enclosed auger-style mixer. This is interrupted auger flighting in a high-shear, high-speed configuration. The auger and shear blades are faced to prevent premature wear and combine the best aspects of all types of mixing - shear, tumble, pressure and counter-current. The augers will mix anything homogeneously. However, if the materials are totally incompatible, the end result may not be the best. "Tuning" the proportions is very important.I think that this method of producing building materials on site is by far the best. It enables the contractor/engineer to have the designed mix virtually on tap. You don't have to mix a batch. Just pull a lever and produce as much as you like. The unused portions reside in the holding bins separate from each other until needed. Mix designs (recipes) can be changed at will. A simple readjustment of the strike-off gates and regulating valves will alter proportions of the materials in the machine immediately. If a change of components is required, just load in the new stuff.If ultimate strength is a consideration, then the mix being produced will most likely be a type of concrete. The most important factor in determining cured strengths of concrete in addition to the cement content is the water/cement ratio (weight of water divided by weight of cement). The lower this is, the better the strength will be, provided there was enough water initially to fully hydrate the cement and aggregates. Typically, a volumetric machine will produce a friendly mix in fifteen seconds mixing time with a W/C ratio of .35. Try to get that out of any kind of batch mixer and use it - on site or ready mix. Simon Stanfield |
Thermoplan or Zeigel Blocks are fired clay blocks which use about 1/3 less energy to make compared to concrete blocks, and about 2/3 less CO2. They are fast, simple and ideal for a self builder to use. About 50% of German homes are made this way and the technology is spreading to other areas of Europe. 
A light-weight super-insulated steel/sheet metal/ polymer cement structure for homes, shelters, or larger structures as per the photos of the model. A steel structure from sloped steel columns in the shape of multiple tripods will be covered by galvinized sheet metal to form a multi-conical shape. Similar shapes can be seen here 
2-Sloped steel support columns are placed in 'tripod' configuration. They will be connected together by welding or mechanical anchors to the concrete slab. Afterwards, they will be painted against corrosion.
The 1:15 model includes some elements that will make it easier to see how this system can be used in regular homes like dormers [for windows], skylights [black] , patio doors [black in the vertical wall] and a floor on part of the second floor supported by horizontal steel beams [image at left]. He applied a polymer/cement mixture to part of the roof to simulate the finished look of the structure. The base in this 1:15 model is 18x9 meters and the height is 6,5 meters [with a usable second floor] but scaling down this same shape could give a 10x5 meter based home with a height of about 3.6 meters with one floor . This could be an excellent size for homes in developing countries.
I feel so strongly about this method of making cementitious building materials that I would like to answer questions and/or become involved in any projects where my expertise might be helpful. I have been involved in concrete for over thirty years and travel the country as a Volumetric Consultant. 
Build Smarter With Alternative Materials by Leon A. Frechette, 1999. Drawing on his two decades as a general contractor in residential and light commercial construction and remodeling, Frechette passes on his experience with recycled, renewable, or otherwise less wasteful materials available commercially for foundations, framing, roofing, doors and windows, insulation, bathrooms and kitchens, and other areas. He describes the material and explains how to use it, when it is and is not appropriate, and how to save both money and labor cost. Sample chapters from can be viewed by going to the publisher's website.
Yurts : Living in the Round by Becky Kemery, 2006. This book journeys from Central Asia to modern America and reveals the history, evolution, and contemporary benefits of yurt living. One of the oldest forms of indigenous shelter still in use today, yurts have exploded into the twenty-first century as a multi-faceted, thoroughly modern, utterly versatile, and immensely popular modern structure whose possibilities are still being explored. Kemery introduces the innovators who redesigned the yurt and took it from back country trekking and campground uses to modern permanent homes and offices. Yurts inspire a sacred connection between people and their environment, between living and nature, between humankind and the forces that shape the world in which we live. Photographs throughout book rouse your imagination, and the extensive resource section gives you the information you need to take the first step toward realizing your own yurt dreams. It is possible to meet our shelter needs without draining natural and personal resources. Yurts can help you reenvision your understanding of home from that of a market commodity to a concept of sacred space in which you can nourish your soul and find your place in the world.
Making Better Concrete: Guidelines to Using Fly Ash for Higher Quality, Eco-Friendly Structures, by Bruce King, 2005. "This is the best and most readable 'how to' guide for using high fly ash concrete -- highly recommended. Using high fly ash concrete is a win-win-win solution: It makes better concrete, costs less, and has a greater environmental benefit than almost any other primary building material out there."-- Scott Shell, Architect, EHDD Architects"At last, a practical guide on HVFAC written for engineers and contractors alike. When it's available, our company will want to buy 25 copies or so to distruibute to our Foremen, Superintendents and Project Managers. While we have been placing HVFAC almost exclusively for the last five years on all of our projects, we have had to rely on our leadership in the field to educate and to pass on their experience by word of mouth and by their example. Now, if they read the book, our men will also understand why HVFAC is such a great technology now and for the future of our planet."-- Deva Rajan, Founder, Canyon Construction"This is an excellent and informative primer on recent developments in high performance fly ash concrete. The "win-win" use of a plentiful man-made waste product to economically obtain better concrete benefits clients, engineers, and the global environment."-- Mason Walters, Structural Engineer and Principal, Forell/Elsesser
Concrete Systems for Homes and Low-Rise Construction by Portland Cement Association, 2005. Fast gaining on more traditional homebuilding materials, concrete systems save builders time, money, and headaches. Offering durability, cost savings, energy efficiency, and eye-pleasing aesthetics, concrete systems now account for large shares of the walls, floors, roofs, finishes, and landscape products in small buildings in the United States. But are concrete systems right for you and your construction crew? And if so, which ones? This is the place to find out. Written by experts from the Portland Cement Association, Concrete Systems for Homes & Low-Rise Construction provides expert, straightforward answers on concrete systems. Open these pages for everything you want to know about availability of products, evaluating concrete systems for homes and low-rise buildings, requirements for application, managing projects, and much more. Based on case histories, field research, and hands-on-the-hammer experience, and with more than 325 photos and illustrations, this one-stop resource shows and tells what you want to know. It's a huge time and money saver! construction.com links to an article about making concrete more environmentally sound. romanconcrete.com links to an article about "Roman concrete" and its similarity to concrete with fly ash. |
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