Watershed Materials - Technology for New Concrete Blocks
The block with a smaller carbon footprint.
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Blog - Watershed Materials - Watershed Block

Blog updates by Watershed Materials. Developments for sustainable new concrete block technology funded by the National Science Foundation.

Back to the Beginning : Radically Re-Thinking the Concrete Block Machine

The evolution of how concrete block are made is striking when comparing Besser’s first machine with its most modern. The fact that concrete blocks themselves haven’t changed in all this time is equally striking. Giant machines churn them out much faster, but they still rely on cement and its high cost and high carbon footprint. Watershed Materials decided to go back to the beginning and invent a whole new way to make a whole new type of structural masonry.

The evolution of how concrete block are made is striking when comparing Besser’s first machine with its most modern. The fact that concrete blocks themselves haven’t changed in all this time is equally striking. Giant machines churn them out much faster, but they still rely on cement and its high cost and high carbon footprint. Watershed Materials decided to go back to the beginning and invent a whole new way to make a whole new type of structural masonry.

In 1904, Herman and Jesse Besser patented the first concrete block machine. It weighed about two hundred pounds and produced one block every three minutes. Today, the Besser Company manufactures a 72,000 pound behemoth they call the Superpac capable of cranking out 3,240 blocks per hour - a 16,000% increase in production capacity. 

Based on that level of innovation, you might rationally wonder why the National Science Foundation funded Watershed Materials’ quest to reinvent the concrete block machine. What could a small California startup offer a one hundred-year-old industry already awash in proven technology?

The answer is “a lot”. 

The innovations that Besser and other industrial titans like Columbia, Hess, Masa, and Tiger bring to concrete block production aren’t focused on revolutionizing what a concrete block could be, but rather are focused on making what is basically the same concrete block they’ve always made, only much much faster - 160 times faster. The Watershed Materials team, on the other hand, wanted to go back to the beginning, to re-imagine the basic premises of what masonry could be - strong, resilient, beautiful, local, sustainable, and affordable.

The first version of our new high compression block machine uses levers and rollers to amplify compressive force by a factor of four. The end gates close off the compression chamber during block fabrication then slide open to allow the finished block to land on the off-loading rollers. The end gate doubles as one of the four sides of the mold. The back end of the mold similarly doubles as an extractor to push the block out of the core. In this image, the end gates are not connected to their hydraulic cylinders.

Jim Adams and Bob McKim were David Easton’s mentors at the Stanford Product Design school. Jim first coined the term “conceptual blockbusting” in 1969 to describe a way of thinking unconventionally. Conceptual blocks are mental walls that block the problem solver from correctly perceiving a problem or conceiving its solution. David and the Watershed Materials team bring this “thinking outside the box” approach to radically re-thinking what a concrete block could be and how they could be made.

Traditional concrete blocks derive all their strength from Portland cement, the chemical glue that binds sand and gravel together. Without cement, a concrete block would collapse before it ever left the mold. Even with cement, fresh concrete blocks are delicate and have to be handled with care. They even have to be put in a steam kiln overnight to cure. Cement and energy to fire the kiln are the two most expensive energy inputs in today’s concrete block production. 

Watershed Materials’ research team found that by intensely compressing individual grains of gravel, sand, silt, and clay together, a block could be made strong without as much cement, and without steam curing. This intense pressure results in a product very similar to natural sedimentary rock. Creating a machine capable of developing this intense pressure became the challenge and the goal.

The first version of our high compression block machine uses low horsepower motors to efficiently power smaller hydraulic cylinders which capitalize on the principle of leverage to magnify the forces. The hydraulic cylinders are kept small to keep the machine efficient and allow it to be run on less power.  As Archimedes said, “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.”

The first version of our high compression block machine uses low horsepower motors to efficiently power smaller hydraulic cylinders which capitalize on the principle of leverage to magnify the forces. The hydraulic cylinders are kept small to keep the machine efficient and allow it to be run on less power.  As Archimedes said, “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.”

Watershed Materials, using laboratory certified mix designs, began producing low cement blocks on machines originally designed for making compressed earth bricks, but upgraded to develop the increased compressive forces. Watershed Blocks made with these enhanced presses are on the market in Northern California today, and are generating rave reviews from architects and the media. Now, with funding from the National Science Foundation, the team is working on a custom designed new machine - faster, stronger, lighter, and more versatile. 

In order to mass produce Watershed Block, our engineers had to figure out how to compress a mixture of locally sourced aggregates with a force so intense as to mimic the process by which stone forms in nature. What kind of hydraulics could accomplish this quickly while not using big electric motors? How could the block mold be strong enough to withstand these compressive forces while also quickly and easily releasing the compacted block seconds after the hydraulic forces are removed? How could the machine apply massive compressive force while itself not being massive? How could the structure be robust enough to support large scale production in a factory environment and light enough to be moved to a construction site for local production?

Archimedes’ lever pivoted on a fulcrum. The Watershed levers rotate around case hardened one inch pins.  Version 1.0, like most prototype original machines, is bolted together. Version 2.0, expected out in late summer 2015, will be water-jetted and pressure fit.

The Watershed Materials engineering team fitted smaller, efficient hydraulic cylinders to a series of levers and fulcrums to magnify a relatively small hydraulic force into a massive compressive force. Rollers and axles work overtime to resist the mold’s expansion during compression and to reduce friction during extraction. The molds are then opened to release the compressive pressure and allow the fresh blocks to travel freely down the offloading line. Intelligent application of simple mechanisms help increase force and decrease friction to allow the machine to be agile and light yet robust enough to withstand many thousands of repeated production cycles.

And here’s another piece of good news: Watershed Blocks don’t have to be treated with the same care as fresh concrete blocks because they’re squeezed together rather than glued, offering increased green strength. And, they don’t require steam curing. Starting from scratch to build a new platform for making masonry block has led to a host of breakthroughs, many of them unanticipated at the outset.

Take a look under the hood.  High strength steel rollers and machined bronze bushings resist 100,000 pounds of outward force yet allow the block to readily slide out of the compression chamber.

We’ve been running the new machine through its paces, making Watershed Blocks, and testing all the processes. We’ve filed patents on the technology. Next, we’ll tear the new machine apart and re-build it again incorporating design changes to allow for faster production, computer control, and more reliable mechanics. We hope to have a completed second iteration ready for production by the end of the year.

Watershed Materials first had an idea of a different kind of concrete block - the same size, shape, and strength; but a smaller carbon footprint and a better appearance. To make a better block like this, a totally new machine had to be invented. With the support of the National Science Foundation and the revolutionary thinking of the Watershed engineering department, we’re one big step closer to the goal.