Words & Photos: Peter Roberts
Spherical Block LLC is a start-up company launching a revolution in advanced masonry technology. This system builds roofs as arches and domes from specialized manufactured concrete blocks. The concept behind this innovation is to keep the entire structure under compression, being squeezed together. This is how concrete is strongest: under compression. Buildings and structures made with this masonry system are affordable, beautiful, very strong, safe, and energy-efficient.
Traditionally, concrete masonry units (CMU’s) have only been used to build straight vertical walls. For over a hundred years, the CMU has done this job very well by providing great value for any building. The benefits of CMU construction include:
- high strength
- fire safety
- insect resistance
- rot and rust resistance
- sound attenuation
Coupled with a variety of appearances made possible through colors added and split-face textures, and made with tight dimensional tolerances in a highly efficient manufacturing process. The high efficiency and low cost have brought the concrete block to virtually every country and have made it a staple of high quality, affordable construction on a global basis.
In addition, CMU’s possess high thermal mass, which can help make a building more energy efficient when properly assembled with the correct placement of thermal insulation. Buildings made with CMU’s have a high resale value and a long, useful life cycle.
Spherical Block’s special masonry units extend the benefits of the CMU all the way to the top of the roof. This masonry system creates extensive design flexibility for the architect, designer, planner, and ultimately the end-user. This is a groundbreaking innovation that is at the nexus of high-efficiency modern manufacturing and traditional masonry arches rooted deep in the past. The end result is a beautiful array of architectural options that are affordable, easy to build, very high strength, fire-safe, and available wherever you can find concrete blocks.
There are three basic types of block that all work together in the design and assembly of masonry arched roof structures. These designs are all described in US Patents issued and assigned to Spherical Block. Molds to produce these blocks have been manufactured for the company by Besser/Proneq. The molds have demonstrated their ability to produce these innovative masonry units with ease. These molds can operate on either Besser or Columbia type block making machines which are already operating in every global market.
The arch block is a rectangular, solid cast unit with two grooves to accept rebar. The dimensions of this block are 8 inches x 16 inches by around 3 inches. The shape has a compound angle in it so that when it stacks it assembles into an arch. This simple design allows for a number of interesting and useful architectural features to be made. Rebar provides support during assembly, so that centering (supporting scaffolding) can be minimized or even done away with completely.
This provides for rapid, simple, and affordable assembly. The molds that Spherical has made operate on a 3 at-a-time block machine (a machine which produces 3 standard 8-inch x 8-inch x 16-inch rectangular CMU’s). These arch block molds will produce 8 arch blocks per cycle, with a cycle time of around 9 seconds: so that arch blocks are made in around 1 second each. The cavities in the arch block mold can be arranged with a divider plate, to produce two half-blocks, which are used at the termination of an arch.
- Door and window arches
- Flying buttresses
- Corrugated arches
- Smooth arches
Hex Block & Pent Block for Dome Roofing
The “hex” and “pent” are triangular blocks used to assemble into spheres or sections of spheres, such as domes. Six hex blocks assemble into a curved hexagon, five pent blocks assemble into a curved pentagon. There are a number of geodesic geometries that these two blocks can assemble into, both together and each by itself. By using a larger number of blocks within any specific geometry, different sized structures (domes and spheres) can be made. Each of these blocks has a groove located in each of its three abutting faces to accept rebar. This lets the block be supported by a framework of rebar so that minimal or no centering or support scaffolding is required.
Ease of Manufacture
All of the Spherical design Blocks are easy to manufacture on both Besser and Columbia type machines. No special materials or handling equipment is required for their production. The molds are mounted on the machine, and standard production using regular concrete mix designs begins. The arch block can be handled, moved, cubed, and palleted using standard automated block production equipment. The hex and pent block are easy to pallet with very minimal manual manipulation. palleted with some manual manipulation required, due to their unique triangular shapes. All three types of blocks have dimensions that correspond to the standard modular coordination for concrete blocks, allowing a convenient and regular stacking on shipping pallets.
Ease of Assembly
Spherical Block’s masonry units are relatively simple and easy to assemble. There is a slight learning curve for the mason to gain familiarity with the various configurations made available by this masonry system. The arched roof sections or domes can either be sprung directly from the foundation or placed on top of vertical walls. The vertical walls must be strong enough to support a concrete block roof, they cannot be standard wooden “balloon frame” construction made of wooden studs. It is recommended that vertical walls be made from standard concrete blocks of 8-inch thickness or more.
#3 rebar (3/8-inch diameter) is recommended for arched roof and dome construction. Rebar is arranged at 8-inch intervals, and is anchored in either the vertical walls (extending down into the core holes of the block) or is anchored directly into the foundation. The rebar is curved into the arc of the roof structure (arch or dome) to create a support structure on which blocks are laid. Blocks are then laid with mortar, in a manner quite similar to which standard vertical masonry walls are assembled. A specific, detailed description of assembly for various structures is beyond the scope of this article: this is simply intended to provide a general overview of the assembly method. It is recommended that a form be provided on the inside of the arch to help the mason create an accurate and more precise arch profile.
The cost of these masonry units is expected to be around the same as regular CMU’s. Arch blocks are expected to be slightly less expensive than 8-inch x 8-inch x 16-inch CMU (around $1 each). Pent and hex blocks are expected to be slightly more expensive than a typical CMU (around $2.50 each). Exact costs will be determined by various block makers, just as the cost of a typical CMU varies slightly between different manufacturers.
Similarly, the cost of the assembly will depend on the rate, ability, and speed of the masons doing the work. Overall, the cost of masonry materials for a building is expected to be around $10-20 per square foot. It is expected that this cost per square foot of materials will roughly double with the inclusion of labor for assembly. This cost reflects the materials and assembly of the masonry shell and does not include all components of a finished building. It is an incredible value for the building owner and establishes a high resale value and a much longer life cycle for the building.
This masonry system takes advantage of the thermal mass benefits created by using a complete masonry building envelope. Masonry has a high specific heat (thermal mass) which provides the ability for the building envelope -including walls and roof- to store heat energy and subsequently release this heat energy back to the inside of the building. This concept also applies to both keeping a building warm in cold weather and keeping a building cool in hot weather.
In order to maximize this thermal mass benefit, it is recommended to place thermal insulation on the outside of the masonry building envelope, like wrapping a warm stone in a cozy blanket. This arrangement creates a delay from the time it takes cold temperatures during winter (or hot temperatures during summer) to travel through the building and affect the interior. This delay also creates a lag on the peak energy demand: that time of day when everyone’s heat has to go on to warm a building, or when everyone’s air conditioning turns on to cool the building. This delay significantly reduces the peak energy demand for a power grid, and power grid requirements are defined by their peak demand.
Concrete block masonry is long known to be safer than competing forms of construction, such as wooden framing. This is known even by children, as demonstrated by the tale Everyone is familiar with the story of the three little pigs and the big bad wolf. Masonry buildings can withstand high winds and severe weather events better than wood frame structures.
However, in America, timber frame homes have long dominated the residential market. Spherical Block’s technology extends the fundamental safety of masonry construction all the way to the top of the roof for any building or structure. Manufactured concrete blocks do not have the same strength in all directions, it is known as an anisotropic material. That is, a concrete block has a high-strength axis, which is the direction of compaction as blocks are made. In conventional CMU’s, this high-strength axis is oriented vertically within a wall. This means that the low-strength axis is oriented horizontally, toward the outside with standard CMU’s.
Spherical Block’s designs always have the high-strength axis oriented toward the outside, so that the building is much better protected from impacts or forces which might hit the building. This is due to the orientation of aggregate within the manufactured concrete, as shown by research conducted by Spherical, as illustrated in this micrograph. The end result is a structure around 70% stronger than standard CMU buildings.
Tornado and Hurricane Safety
Tornadoes and hurricanes frequently cause extensive damage to buildings and homes every year. It is common to see homes with their roofs ripped off, damaged, or destroyed following either a tornado or hurricane. Spherical Block alleviates this threat by providing buildings that can withstand the extreme forces and loading created by both tornadoes and hurricanes. This technology provides safer, more secure homes for communities living in areas prone to either tornadoes or hurricanes. Climate change is increasing the risk and vulnerability of homes, buildings, and shelters as extreme weather events and the damage they create are expected to continue to rise.
Recent wildfires across the American West (especially in California) have reminded us all how dangerous and lethal wildfires are, and how easily standard wooden homes are destroyed by fire. Spherical Block’s designs are very well suited to withstanding this threat, by extending the non-combustible, fireproof concrete block all the way to the top of the roof.
Burning embers can be carried aloft for miles, and create a significant threat when they land on a combustible roof. One of the most dangerous threats in a burning building is a collapsing roof, which is sadly responsible for many tragedies every year. Spherical Block’s building system removes this threat and increases the safety of buildings and homes. Because these blocks are solid, they create a greater thickness of concrete between the outside and interior of a building.
This thickness of non-combustible concrete translates directly into an increased fire safety rating, which is expressed in hours of safety provided. Typical CMU’s provide around 2 – 2.5-hour fire safety rating; this technology is expected to provide around 4-6 hour safety rating, due to the increased thickness provided by solid concrete construction (fire safety testing is still required to confirm this expectation). Once this fire safety rating is confirmed, buildings made with Spherical Block’s LLC’s technology properly configured (including air-tight rooms, proper fire windows, doors, etc.) will provide people with the ability to shelter in place and survive wildfires.
Too many people evacuating their homes during a wildfire have been killed in the act of evacuation, traffic is often stopped and fires move quickly. The ability to shelter in place in a safe and secure building removes this threat. The affordability and ease of assembly of this technology offer the promise of fire-safe buildings made available to homeowners everywhere.
Ballistic and Blast Protection
Spherical Block LLC is involved in the joint development of its technology with ProtectiFlex technology involves ductile and elastomeric composite material used to create masonry appropriate for blast and ballistic applications, defense applications, hardened structures, seismic applications, and severe weather events. ProtectiFlex provides proprietary technology combining recycled non-biodegradable material, composite fibers, and/or rebar in a cement matrix.
This material offers protection and can be used to mitigate risk against accidents, natural disasters, and direct attacks. This material design prevents bullet penetration, reduces spalling, and can absorb large amounts of energy without diminishing structural integrity. It has 20 times the strain capacity of traditional concrete before failure.
Spherical Block LLC is currently completing Phase II work sponsored by the National Science Foundation on the development and testing of its technology. One of the main goals of this research is to obtain a listing from the International Code Council – Evaluation Services (ICC-ES). This listing is forthcoming and is expected to be published this year. Obtaining this listing will be followed by a series of Evaluation Reports also to be done by ICC-ES.
These series of certifications, listings, and evaluations will help provide specifiers (including architects, engineers, and designers) with the characterization of this masonry system and the assurance of quality control systems being employed by the manufacturer. Spherical Block’s masonry units are currently manufactured by Southern Tier Concrete Products Corporation located in Alfred, New York, who are receiving the ICC-ES listing as a manufacturer.
Unique New Applications
The unique nature of Spherical Block LLC masonry designs make several exciting and entirely new applications and uses for masonry available.
- The hex and pent blocks can be used to assemble an entire sphere. This arrangement creates the ability to provide storage tanks that are affordable, very strong and easy to install for multiple applications. These tanks can be used for rainwater harvesting (rwh) where the roof of a building serves as the catchment area for rainfall, and gutters collect and divert rainwater for storage in one of these spherical tanks.
- These spherical tanks can also be used as septic tanks. These septic tanks are much less expensive than conventional monolithic cast concrete septic tanks and do not require a crane and/or heavy equipment for installation.
- Large spheres and cylinders can also be constructed for storage in the energy sector for oil and natural gas.
- The arch blocks can be used to assemble as a load-bearing arch and can be used as a bridge. This application can help fulfill a huge need for infrastructure in the US: currently, concrete bridges have a relatively short useful life cycle of around 50 – 100 years. By contrast, the masonry arch structures used by the ancient Romans in their aqueducts (used to deliver potable water to cities) are still standing strong after 2,000 years. By using fiber reinforced plastic rebar, Spherical Block LLC masonry arches will not suffer from rust damage which leads to the short life cycle of typical concrete bridges, which are prone to failure following the rust and degradation of concrete due to metal rebar.
- Both the arch block and the hex & pent blocks can be used to assemble other infrastructure elements, including tunnel linings, water drainage culverts, levees, breakwaters, and other public works that comprise infrastructure.
- The arch block can also be used to assemble as an inverted (or upside-down) arch. This arrangement can be used to create the hull of a ship or barge. That’s right: a concrete ship is made possible by this masonry system. Such a vessel would never rust, it is expected to have a very long life cycle, and would be available at a fraction of the cost of a conventional steel-hulled ship. In this configuration, the hull is divided into a series of compartments by bulkheads. These bulkheads can be made from standard CMU’s which incorporate rebar for tensile strength. Rebar is also included in the curved hull section itself, in the same manner, that rebar is included in a masonry arch. While Spherical Block LLC has not yet built a ship using its block designs, a US Patent has been issued to the company and the idea holds great promise for creating high-strength, low cost, boats, vessels, ships, and barges.
- The idea of a concrete block ship or vessel or hull can be further extended to include the design of a masonry submarine. The high compressive strength of concrete provides a means of building an enclosed submersible vessel. A sphere is the ultimate high-strength configuration since the compressive stress is uniform around the entire structure. Spherical Block LLC anticipates that a first prototype submarine would be relatively simple to assemble and test.
- There is potential to help rebuild ocean wildlife habitats by submerging domes for sea life to inhabit, to help increase biodiversity.
Seeking Collaborators and Early Adopters
Spherical Block LLC is eager to team up with engineers, architects, construction firms, masons, block makers, and others who are interested in using this new technology and helping bring the benefits of this novel innovation rooted deep in our past to a bold new future. Successful use of this technology will help create new markets for the masonry industry and launch this innovation nationally and globally, providing benefits to society, humanity, and the world.
Spherical Block expects to have its technology available for sale as a commercial product in the near future. The listing from ICC-ES is forthcoming, this certification will facilitate market entry, as the product will have a specified compressive strength and quality control system in place so that this system can be specified for various applications by architects, engineers, and designers. Currently, Spherical Block LLC products are simply awaiting the ICC-ES listing, and will then be available for sale. The company’s initial supply of products will be available from Southern Tier Concrete Products Corporation in Alfred, NY.