About CityMix, Inc.

Patented Ultra-Lightweight Synthetic Aggregate for Concrete

Concrete is one of the most widely used building materials in the world, and for most of its 2,000-year history, the fundamental recipe has stayed the same: cement, water, and heavy natural aggregates — sand, gravel, stone — mined from the earth, processed, transported, and mixed in quantities that drive weight and carbon costs at every stage of production.

CityMix, Inc. was built around a single question:

What happens when you replace that heavy aggregate with something that weighs almost nothing, performs better, and comes from material that was going to a landfill anyway?

The answer is a patented ultra-lightweight synthetic aggregate that is changing how concrete manufacturers, precast producers, and concrete product companies approach weight, performance, and sustainability across a wide range of commercial, residential, and decorative applications.

Who CityMix Is

CityMix, Inc. is a materials technology company headquartered in Seattle, Washington, specializing in the development and commercialization of ultra-lightweight synthetic aggregate for concrete and cement-based products. The company serves concrete manufacturers, precast producers, and concrete product companies throughout North America, with operations covering both the United States and Canada.

CityMix provides LEED documentation support for manufacturers seeking to incorporate the product into green building projects. The use of recycled-content aggregate in concrete products contributes to multiple LEED credit categories, and CityMix representatives work directly with manufacturers to provide the documentation that project teams and certification bodies require.

The Patent and the Inventor

The technology behind CityMix was invented by Michael W. LeBlanc and is protected under U.S. Patent No. 8969464, granted March 3, 2015, assigned to CityMix, Inc. The patent was originally filed April 13, 2012 under CLP Technologies, LLC, which became CityMix, Inc. in 2014.

The patent covers the core innovation that makes CityMix fundamentally different from conventional EPS bead additives: a process for encapsulating expanded polystyrene waste particles in a proprietary coating that uses fly ash, silica fume, and similar materials to produce a particle that is static-free, non-hydrophobic, and capable of chemically bonding to cement paste. The patent abstract describes the aggregates as providing “an improved means for manufacturing lightweight concrete that is significantly stronger than conventional lightweight concretes” — a claim that laboratory testing and field applications have consistently borne out.

You can verify the patent directly through the United States Patent and Trademark Office.

The Technology

CityMix looks like coarse, light gray sand. Each individual particle consists of an inner EPS core — sourced from recycled waste foam — encapsulated in a proprietary outer coating that makes it static-free, non-hydrophobic, and capable of bonding directly and permanently to cement paste. The result is a synthetic aggregate that disperses uniformly throughout any mix design, bonds with the cement matrix rather than floating or segregating, and stays locked in place through curing and beyond.

Conventional EPS beads — even those treated with fire retardants — are statically charged, hydrophobic, and incapable of forming a meaningful bond with cement. They float, they segregate, and they ignite.

CityMix particles do none of those things.

The proprietary outer shell transforms the fundamental behavior of the EPS core in a cement environment, producing performance characteristics that raw EPS bead additives cannot achieve.

Our Credentials and Verifiable Standards

CityMix’s performance characteristics are not proprietary claims alone — they are supported by independent testing and third-party verified standards:

• U.S. Patent No. 8969464 — Granted March 3, 2015, covering the synthetic aggregate composition and manufacturing process. Verifiable through Google Patents.
• ASTM E84 Class A Fire Rating — CityMix particles are non-flammable and carry a Class A rating for both Flame Spread and Smoke Developed under ASTM Standard E84, the standard test method for surface burning characteristics of building materials. Standard EPS beads ignite and support flame even when treated with fire retardants. CityMix does not.
• Non-Hazardous Classification — CityMix is classified as a non-hazardous material. The full Material Safety Data Sheet is available from a CityMix representative upon request.
• LEED Documentation Support — CityMix provides LEED documentation for manufacturers and project teams incorporating the product into green building projects. The product’s recycled content and potential for net carbon reduction support multiple LEED credit categories.
• 20 to 30 Percent Higher Compressive Strength vs. Conventional EPS — Laboratory testing consistently shows that CityMix produces 20 to 30 percent higher compressive strength readings in finished concrete than products using conventional uncoated EPS bead additives, due to the chemical bond the proprietary outer shell forms with the cement matrix.

These credentials are independently verifiable and distinguish CityMix from alternative lightweight aggregate products that lack the same combination of fire rating, bond strength, and recycled content.

Performance Numbers

A few specific figures establish what the product actually delivers:

• Weight — CityMix weighs approximately 3 lbs per cubic foot. Conventional fine aggregates weigh 90 to 100 lbs per cubic foot. Even modest volume substitution rates produce significant overall product weight reduction.
• Weight Reduction Range — Structural concrete applications typically support 5 to 10 percent weight reduction while meeting minimum code and engineering requirements. Non-structural concrete products — landscape blocks, parking curbs, veneer stone, decorative moldings — can be reduced by as much as 80 percent while remaining fully suitable for their intended purpose.
• Stucco Applications — CityMix has been formulated into stucco base coats producing 35 percent weight reduction alongside improved mixing, pumping, and application performance, and reduced fall-off waste.
• Veneer Stone Applications — CityMix has worked with veneer stone manufacturers to develop formulations enabling 20 percent weight reduction in standard products and up to 75 percent weight reduction in ultra-light formulations.

Sustainability

CityMix is composed of approximately 99 percent pure recycled waste by volume. The inner core of each particle is expanded polystyrene — the foam used in packaging, insulation, and food service products that constitutes one of the largest-volume waste streams in North American landfills. Every unit of CityMix produced diverts that material from landfill and replaces mined natural aggregates that require energy-intensive extraction, processing, and long-distance transport before they reach the concrete plant.

Traditional concrete products are made from heavy, rurally mined natural materials requiring energy-demanding removal, processing, handling, and transporting at every stage. The use of ultra-lightweight, recycled-content CityMix aggregate provides significant potential for net carbon reduction across the full production, transport, and installation lifecycle.

CityMix provides LEED documentation support for manufacturers and project teams who need to demonstrate the product’s sustainability credentials as part of a green building certification process.

Applications and Who We Work With

CityMix works with manufacturers throughout North America across a broad range of concrete product categories, including:

• Precast concrete building panels and architectural elements
• Concrete masonry units and landscape blocks
• Veneer stone and decorative concrete products
• Parking curbs, traffic barriers, and site furnishings
• Stucco base coats and exterior cladding systems
• Concrete pipe and utility products
• Specialty architectural and decorative moldings

The percentage of CityMix that replaces conventional aggregate is fully customizable for each application, which gives the product a practical range from lightly modified structural mixes to dramatically lightened non-structural products. CityMix’s technical team works with each manufacturer through the mix design process to identify the right substitution rate and ensure that critical performance properties are maintained.

Technical Support

Weight reduction in concrete is not a simple variable swap. Even modest changes to aggregate composition can affect mixing behavior, de-molding time, set and cure characteristics, compressive strength, surface finish, freeze-thaw performance, and other properties that matter in production. CityMix’s technical experts work directly with manufacturers through the full mix design process — from initial laboratory testing through production trials and full implementation.

That support covers mixing and batching procedures, adjustment for manufacturer-specific equipment and processes, verification of effective volume replacement factors, and ongoing consultation as mix designs evolve. Manufacturers working with CityMix receive the technical expertise behind the product throughout the implementation process, not just the ingredient itself.

Contact CityMix

CityMix, Inc. is headquartered in Seattle, Washington. Our technical and sales team serves manufacturers and concrete product companies throughout the United States and Canada.

United States: (916) 765-9290
Canada: (604) 997-3355
Mailing Address: 1425 Broadway, Box 498, Seattle, WA 98122

To request product data, discuss a specific application, or begin a mix design consultation, reach out through the contact form on our website or call us directly.