Between trips to Mexico and Taiwan, Robert Gross landed in his Orlando, Fla., office just long enough to catch his breath, then sigh and shake his head at the roughly 6,000 pieces of mail awaiting his attention, and field a few questions. The thousands of letters, telexes, and telegrams are from all over the world, from countries where there are large numbers of homeless people and little means for providing them with shelter -- India, Bangladesh, Chile, Ghana.
``Some of the letters,'' says Mr. Gross, ``are so sad, they just make you want to do something. Some of these people need housing so badly.''
Gross is ``doing something.'' Last year, he was ready to tell anyone who would listen that his company, Terrablock Worldwide, offered the only machine on the market that turns a readily available resource (dirt) into a building material that can meet the needs of the estimated 1 billion people worldwide considered to be inadequately housed.
His inspiration to build such a machine came about 12 years ago, after watching workmen build a home in Arizona out of expensive adobe blocks made in Mexico. Gross became interested in the possibility of designing a machine that would manufacture adobe blocks. The ensuing years found him studying, sketching ideas, comparing and testing designs -- deepening his knowledge of adobe and its value as a building material.
Encouraged by the fact that an adobe structure -- the Taos Pueblo in New Mexico -- has been lived in for some 900 years, Gross felt that these doeskin-colored blocks could be an overlooked building material for today. Adobe's constituents -- clay, sand, and aggregate (minerals) -- can be found almost everywhere, and are abundant in the third-world countries where housing is desperately needed.
Gross says his goal became ``to bring back an old technology as a new and modern technology.''
His first task was to change the labor-intensive method of making adobe. By hand, two workers can mix and mold about 300 blocks a day. The blocks then require at least seven days to dry, and must be laid out separately. In less-favorable weather conditions this drying process can take seven to eight weeks.
Little more is required to operate Gross's adobe-block machine than someone to push the ``on'' button and keep the hopper loaded with soil. His machine produces a block every 10 seconds; the blocks can be used immediately or stacked for future use.
During the time that Gross was designing, testing, and eventually manufacturing his machines, development experts around the world began to consider more closely the question of how much energy is required to produce a unit of building material.
Measuring such energy costs includes considering even the human energy expended to mold a block, tie grasses together, or pull a machine to a work site. The energy efficiency in manufacturing building materials is every bit as important as the insulation efficiency of the final product -- especially when considering solutions appropriate to problems in the third world, where energy resources are scarce.
According to Mr. Gross, much of the pioneering work on this issue has been undertaken by Paul McHenry, an adobe expert in Albuquerque, N.M. For 26 years, Mr. McHenry, an architect who specializes in historical preservation, has been documenting adobe's worldwide utility as a building material.
Research by McHenry has shown that adobe is a great deal more energy-efficient to manufacture than most other building materials.
According to him, the material is already well known for its insulating qualities. It has a great ability to store heat, then balance out the highs and lows of the temperature outdoors -- giving adobe a ``warm-in-the-winter, cool-in-the-summer'' reputation.
Not so well known, says McHenry, is the fact that manufacturing with adobe instead of concrete [gravel, sand, and cement] results in a 60 to 70 percent energy saving. (Concrete has long been considered one of the best building materials.) And, according to Gross and McHenry, the fully automated adobe block machine makes the manufacturing process even more energy-efficient.
Making adobe easier and more cost-efficient to manufacture has been a key to arousing the attention of engineers and agencies working on third-world development.
One issue that Gross, unlike many of his colleagues, has not had to deal with is the third world's rejection of adobe. In the eyes of many, adobe buildings are the housing of the poor. The handmade blocks are rough, not wholely symmetrical, and debris indigenous to the soil is often visible.
Although adobe block has been used for centuries to build castles, mosques, missions, pueblos, and homes, it went out of style in the early 1900s. This was in part because of its socially unacceptable image. In fact, in many North African and Middle Eastern cities, whole neighborhoods of adobe dwellings were bulldozed and replaced with concrete-block buildings. To this day, many people in third-world countries cringe at the mention of adobe.
No one cringes, however, when Mr. Gross appears with his machine. ``The thought,'' he says, ``of a dry, solid home . . . is very exciting to people who have never had sturdy dwellings.''
The uniformity and smoothness of the machine-made adobe blocks make it possible to lay them with traditional mortar, bond them with grout, or simply stack them dry. The dry-stack method requires no skilled masonry work, only a solid foundation and proper leveling of the blocks as they are stacked. This method is especially suited to third-world countries.
For people who have never built anything in their life, never even hammered a nail, using the machine-made adobe block is very satisfying, Gross says. A trip to Gabon to demonstrate his machine, for example, ended in jubilation when the locals made blocks and put up a small building in less than two days.
For his company, the excitement has just begun. Last year Gross was invited by the World Bank to attend a United Nations symposium in Belgium on earth structures appropriate for developing nations. There, he had the opportunity to meet and discuss his machine with representatives of the housing ministries from a number of these nations, relief agencies, and many people who are working to provide low-cost shelter for the world's homeless.
The World Bank's backing -- indicated by its invitation to the symposium -- and Gross's attendance at the symposium brought his machine to the attention of the developing world.
The machine is already being used in African countries, Malaysia, and Saudi Arabia. Other sales are pending. Right now, Gross and his staff can barely keep up with the demand for information and product demonstrations.
Although he is not the only manufacturer of such machines -- there are at least six others -- he appears, at least for now, to have a corner on the third-world market. According to him, none of the other machines are fully automated, nor do they produce bricks as fast. And his machine, according to veteran expert McHenry and sources at the World Bank, is the best designed and most sturdily built.
So far, says Gross, there have been no problems that have required him or one of his partners to go to a site to repair a machine. His most recent sale has been operating for a couple of thousand hours with no problems.
The real challenge, Gross concedes, is maintenance of the machines. During the design stage, he realized that these machines would probably never know the luxury of regular maintenance or a storage shelter. Thus, says Gross, a retired National Aeronautics and Space Administration engineer, he used only ``the very best materials.''
He also assumed that the people who would value his blockmaking machine the most might not be able to run a machine that required a great deal of technical knowledge. Thus ``I was trying to get it as near perfect [as possible] for someone to whom machinery is foreign,'' says Gross.
``The machine can be pulled to any job site in the world, and as long as someone pushes the start button and keeps shoveling soil into the hopper, it will keep producing bricks.'' On one gallon of diesel fuel, the machine will run for an hour -- and in that time produce enough blocks for a 100-cubic-foot wall. Facts about the adobe brickmaking machine The machine, a compact 88 inches wide by 90 inches high by 16 feet long, weighs about 9,000 pounds. It operates for about one hour on one gallon of diesel fuel; in that time it produces about 600 adobe blocks. Using hydraulic pressure of up to 440,000 pounds per square foot, the machine molds 30 pounds of dirt into a single block 4 inches tall, 12 inches wide, and 10 inches deep. The hydraulic system holds 150 US gallons of oil. The hopper capacity is 84 cubic feet. It is powered by a Mitsubishi diesel engine, which is sparked by an electrical system consisting of two 12-volt storage batteries. Moisture content of the soil used for adobe needs to be 4 to 14 percent. Ninety-four percent of all readily available soils fall into this range. Usually, no additives are needed. Cost of the machine: about $85,000. Source: Terrablock Worldwide, Orlando, Fla.
Second of two stories. ``Adobe: a new look at a centuries-old building material'' ran in yesterday's Monitor.