CityMix is a patent-pending, ultra-lightweight synthetic concrete additive consisting of individual expanded polystyrene (EPS) waste particles encapsulated in an applied coating. The product is static free, mixes easily and uniformly, and bonds extraordinarily well to cement paste.
The product provides an opportunity for partial substitution of the heavy sands and gravels in cement-based mixtures with an equal volume of the ultra-lightweight CityMix material in order to reduce overall product weight.
CityMix also helps to enhance certain desirable cement-based product performance characteristics such as flexibility, resilience, water repellency and crack resistance.
CityMix looks like a course, light gray sand, with each individual particle consisting of an inner core of an irregularly sized EPS fragment encapsulated in a non-toxic and performance-enhancing outer shell. The finished product is composed of approximately 99% pure recycled waste (by volume), thereby creating – to the best of CLP’s knowledge – the “greenest” and most lightweight additive ever made commercially available for use in cement-based products.
The actual percentage of CityMix lightweight synthetic aggregate that may be substituted into any given concrete mixture is fully customizable, thereby allowing the product to serve as a suitable weight-reducing material for a wide variety of cement-based products and applications. For example, a structural concrete building panel might only be able to be reduced 5% -10% in weight and still retain its minimum code or engineering requirements, but common non-structural concrete objects like landscape blocks, parking curbs, veneer stone or decorative moldings, for example, might be reduced in weight by as much as 80% and still be fully acceptable for their intended purposes.
Laboratory testing and ever-increasing responses from the cement products industry consistently substantiate the belief that CityMix may prove to be the single best retained-strength-to-weight-reduction discovery in the 2,000 year history of hydraulic cement concrete.
CityMix is classified as a Non-Hazardous material (see MSDS).
- Ultra-Lightweight Additive (Appx 2.5 – 3.0 lb/ft3)
- Non-Static Handling
- Mixes Easily & Uniformly
- Non-Combustible (ASTM E84 Class A Flame and Smoke Rating)
- Contains 99% Recycled Content (By Volume)
- Helps Reduce Transportation, Handling and Installation Costs
- Enables Lighter Structure Weight
- Permits Mixture Adjustment to Achieve Specific Unit Weight
- Improved Freeze-Thaw Resistance
- Increased Flexural Strength
- Tailored Compressive Strength
- Improved Crack Resistance
- Improved Thermal Resistance
- Decreased Permeability
CityMix Advantages Over Other EPS Products
No static. Easy to handle CityMix is static free, and at approximately double the bulk density of typical, uncoated EPS material (3 lbs / ft3 vs. 1.5 lbs/ ft3), the product provides enough particle weight to enable containable and controllable handling.
Easy to Mix CityMix is not hydrophobic during the blending process so it will easily and quickly incorporate into wet concrete mixtures. Most common types of mixing equipment such as paddle, pan, drum or ribbon mixers can be used.
Excellent bond strength to cement CityMix chemically bonds to the cement paste in a concrete matrix, thereby preventing the “popcorning” release of individual particles from the finished product when cutting or abrading.
Uniform aggregate dispersion CityMix static-free particles blend rapidly and uniformly in nearly any mix design, thereby ensuring continuity of finished concrete strength.
Improved compressive strength CityMix’s proprietary outer shell and varying particle shapes and sizes typically help generate 20-30% higher compressive readings than concrete products using conventional EPS bead additives.
Improved fire resistance Standard EPS beads, even if “modified” with a fire retardant, will ignite and support flame. City Mix particles are non-flammable and Class A rated for Flame Spread and Smoke Developed (under ASTM E84).
Sustainable building product CityMix helps recycle the largest volume consumer waste product in the North American landfill into a lightweight, user-friendly and performance-enhancing additive for concrete, the world’s most common building material. Traditional concrete products are typically made with heavy and rurally mined natural aggregates requiring energy-demanding processing, handling and transporting equipment and procedures. Conversely, the use of recycled, ultra-lightweight CityMix-containing concrete provides significant potential for net carbon reduction. LEED documentation support and other product sustainability information is available from your CityMix representative.
IMPORTANT NOTE CityMix is designed to serve as an ultra-lightweight VOLUME SUBSTITUTION MATERIAL for equal parts by volume of natural aggregates and SHOULD ONLY BE MEASURED BY VOLUME, never by weight. Even minor particle size and density variations can have a significant effect upon CityMix weight or bulk density. Measuring or adding the product into a batch mix by WEIGHT is never advised. To begin the mix designing process, the effective volume of CityMix should be regarded as approximately 50% of the bulk volume, which is similar to natural aggregates, such as sand. Test mixing should always be performed to verify or adjust the effective volume factor of CityMix. Minor variations can be expected due to each individual manufacturer’s mixer, materials and/or process.
Understanding the CityMix Particle Structure
To help understand how the CityMix product works, it may be helpful to appreciate the composition of the particle’s foam inner core from a microscopic level. EPS packaging and insulating material is composed of thousands of tiny individual air-filled beads, which are not hollow, but are instead filled with hundreds of even smaller air-filled beads (imagine each whole bead as a soccer ball with dozens of tiny integrated ping pong balls inside). So, when CityMix manufacturing machinery reduces scraps of waste EPS packaging foam to a fine grind, the resulting shredded particles still contain fully sealed air bubbles regardless of the degree of slicing, tearing, compression or other malformation to which they are subjected. And not only do the ground and irregularly surfaced foam particles then have more surface area to which the applied, performance-enhancing and static fee particle coating can attach and bond, but CityMix varying particle shapes can then interlock within the aggregate mix to generate higher compressive strength.
The CityMix outer particle coating not only effectively bonds to and encapsulates the EPS-based inner core, but it also bonds exceedingly well with the cement paste contained in concrete mixes. This tight bond with the cement component permanently locks the CityMix semi-pliable air-filled particles in place, which helps concrete to achieve a certain degree of innate flexibility and resilience, as compared to mixtures infused with uncoated, statically charged, hydrophobic and thereby unsecured conventional EPS beads.
Although the weight of a cement-based product can easily be reduced by exchanging a portion of CityMix for an equal volume of the much heavier sand or fine aggregates contained in any given ingredient recipe, many modern formulations are highly specialized and sometimes even slight changes can affect other critical product performance properties. CityMix technical experts are readily available to help production manufacturers and other users to not only reduce overall product weight to the exact desired degree, but to ensure that critical individual acceptability standards for mixing and pouring, de-molding, set and cure times, compressive strengths, fire ratings, cosmetic needs and other vital factors are also achieved.
Downloadable Technical Information (.pdf files)
Product Flame Resistance Demo:
Other available services from your CityMix representative
- Mixing, Handling and Application guidelines
- Lightweight Mix Design Development
- Process Manufacturing Support
- City Mix Promotional and Sustainability information and support
- Testing and Certification Data
- Specific Support Information for various trade, union, industry association manufacturer or other professional needs.