Brick and Block
Modern masonry technology adapts to contemporary needs, while maintaining a heritage of strength and greatness.
By Alex Wright
In August 2014, the strongest earthquake in two decades struck the Bay Area of California, causing hundreds of millions of dollars in damage, killing one person and injuring hundreds. Scores of buildings were shaken apart.
Among those jolted awake in the early morning hours was a team of technology developers with a unique concern: They had overseen construction of a modern, multi-level home built entirely of hollow cell, through-wall structural masonry. The home sat almost directly on the fault line. Most concerning of all was the specific nature of the masonry. It had been produced with a new, alternative technique. As the sun rose, the team assembled at the building site to assess the destruction.
What they found was beyond anything they had imagined. The home stood exactly as it had the day before, without a discernable crack or any structural damage. The home had ridden atop the undulating earth, yet offered no clues that the earthquake had even taken place. The team felt fortunate, especially after learning of the widespread damage others had suffered. More than anything, the team felt an intense validation that a new experiment in masonry had been substantiated by a cataclysm that no testing regimen can duplicate.
The home was the first built entirely of a new form of masonry called Watershed Block, which encapsulates the advantages of modern concrete masonry: durability, energy efficiency, local production and modern aesthetics. Watershed Block also uses one-third less cement than traditional concrete masonry. The home went on to be featured in Dwell magazine and inspired other projects built of Watershed Block, which garnered an Architzer award. But most important, that morning, staring at the 18-foot-tall Watershed Block walls, the team knew they were on the threshold of another evolution of masonry.
A long history of innovation
Masonry has experienced more cycles of innovation than any other modern building material. The Egyptian pyramids, made of masonry, were the tallest manmade structures on earth for more than 3,800 years, until the Lincoln Cathedral in England was completed, also using masonry. The Romans pioneered an early form of concrete masonry, much of which exists today. Concrete masonry has experienced unbelievable advancements over just the last century. Modern CMU machines push out thousands of block an hour, a 10,000 percent improvement over the first concrete block machine pioneered by Herman and Jesse Besser.
As masonry continues to evolve, so do public values and expectations of the built environment. The masonry industry has remained committed to offering sustainable solutions for homes, businesses, schools, churches and civic buildings. Despite this commitment, one aspect of today’s concrete masonry has remained elusive to modern expectations of sustainable building materials. According to the Portland Cement Association, 91 percent of the carbon footprint of concrete masonry comes from the cement. The production of cement is responsible for 6 percent of the entire world’s CO2 emissions.
Watershed Materials was formed in 2011 with the mission of reducing cement in concrete masonry – one evolution in a long line of masonry advancements going back over 10,000 years. The team focused on a few solid principles: Use intense compression to lithify block into a kind of manmade stone, utilize the natural binding characteristics of the rock dust normally washed out of aggregate, and use as little cement as possible to meet industry standards for structural masonry.
From the beginning
Leasing an abandoned Basalite factory in Napa, Calif., the Watershed Materials team started with a pair of block presses from ITAL and reconfigured them to explore enhanced compression. Rather than simply replacing cement with another chemical binder, the team studied how to increase block strength by re-engineering the mechanics of inter-particle binding. Rock forms in nature over thousands of years as loose mineral grains are fused together under intense pressure. Replicating this amount of pressure in a factory environment could provide much of the strength normally contributed by cement. The problem was that the team couldn’t find anyone making a block machine capable of generating the forces required to lithify aggregate grains and achieve the performance metrics of ASTM C-90 at low cement ratios.
In 2013 and 2014, the research team was awarded a series of grants from the National Science Foundation to produce zero cement structural concrete masonry. The grants provided research funding on two simultaneous fronts. The first was to produce a radically new machine capable of manufacturing block under intense pressure, while still delivering a throughput necessary for production at scale. The second was to produce formulations for zero cement masonry. By this point, the Watershed Materials team had achieved cement reductions of 50 percent, but that wasn’t enough for the National Science Foundation’s Small Business Innovation Research review panel, which has the motto, “High Risk, High Reward.”
Reducing cement and CO2
Watershed Materials is reducing cement in structural masonry, while utilizing the natural attributes of locally sourced, minimally processed, and often-recycled aggregate to produce stunning masonry products that appeal to architects on the lookout for new aesthetics. Several product lines are in current production. The most recent is a zero cement formula that incorporates a blend of lime, blast furnace slag and naturally occurring minerals. Block made with this zero cement formula achieve 2,500 psi with a nearly porcelain white appearance. Watershed Materials also offers a low cement block formulation that incorporates a wider range of repurposed aggregates.
Most interesting is Watershed Materials’ zero cement geopolymer formulation that uses no fly ash, no blast furnace slag, no metakaolin and, most important, no cement, while maintaining structural integrity. Recent test samples have achieved 7,000 psi. The geopolymer technology is markedly different from fly ash-based geopolymers, because it doesn’t rely on any pozzolanic industrial byproducts and, instead, activates and stabilizes ordinary clays found readily in aggregate sources around the world. By stabilizing abundant natural clay minerals to produce long-lasting, high-compressive strength, weather-resistant masonry, Watershed Materials has opened the door to a new evolution in masonry.
Masonry products made with all of these mix design formulations are produced using the company’s new high-compression block machine technology. Demonstrations are being scheduled for construction and manufacturing industry representatives from the United States and other countries where concrete block are made in even more staggering numbers.
Watershed Materials’ masonry expands on many of the advantages of concrete masonry. Energy efficiency, durability, local production and interior air quality are maintained just as they are with concrete masonry. Building on these values, the company’s technology offers two further evolutions. Using less cement while maintaining structural integrity lowers the carbon footprint of one of the world’s most common building materials, and reduces the cost of one of the most expensive components in concrete masonry. Using unwashed, often recycled aggregates saves water, expands the available sources of aggregate and, importantly, allows masonry to display the region of its production without using artificial dyes or colorants.
Moving forward, Watershed Materials is targeting the technology to both developed mass-production markets as well as developing markets where cement is often imported and expensive. As the Bay Area earthquake of 2014 proved, modern masonry technology can adapt to contemporary needs, while maintaining a heritage of strength and greatness.
Alex Wright leads the business development team at Watershed Materials. For more information, visit http://watershedmaterials.com.