Project Vault – Natural Pozzolan & Critical Minerals

Project Vault is Environmental Minerals Inc.’s internal technical vault for research and documentation on ASTM C618 Class N natural pozzolan, AGRIPOZZ soil conditioner, and the Company’s associated critical minerals opportunity within the California volcanic pozzolan system. This page provides a narrative overview of that body of work for engineers, specifiers, and institutional partners.

Environmental Minerals – Natural Pozzolan for Rock-Solid Concrete

A legacy source for infrastructure, agriculture, and low-carbon concrete.

The Material That Built Empires

For nearly two millennia, natural pozzolan—a quiet volcanic ingredient—has demonstrated unmatched performance in concrete, surpassing many modern alternatives. The Romans, who discovered the value of volcanic ash near Pozzuoli, Italy, used it to create concrete that has stood the test of time. Their mix of volcanic ash, lime, and water resulted in structures that endure to this day:

  • The Pantheon’s 142 feet wide dome, constructed around 126 AD, remains the world’s largest unreinforced concrete dome, built using natural pozzolan.
  • Roman harbors have withstood over 2,000 years of saltwater exposure.
  • Aqueducts continue to deliver water across Europe.
  • The Colosseum has survived earthquakes and centuries of use.

Roman pozzolan concrete becomes stronger over time, while modern concrete structures typically weaken after 20 to 40 years.

Further reading:

The Secret Ingredient: Natural Pozzolan

Natural pozzolan is a form of volcanic ash rich in reactive silica and alumina. Today, it is known as a supplementary cementitious material (SCM), which serves as an additive that partially replaces Portland cement in concrete for improved performance. The Romans understood the effect, if not the chemistry: volcanic ash, lime, and water produced concrete with remarkable longevity.

Defining Pozzolan (ACI 116R)

According to ACI 116R, a pozzolan is:

“A siliceous or siliceous-aluminous material which, in itself, possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties.”

In simpler terms, pozzolan works in concert with cement to produce concrete that is denser, stronger, and longer lasting.

References:

Environmental Minerals Heritage: Los Angeles Aqueduct

In the early 1900s, Los Angeles needed to transport water across 233 miles of harsh desert. Engineers, inspired by Roman construction methods, identified similar volcanic deposits in California’s Mojave region. Using natural pozzolan from our mine site, they built the Los Angeles Aqueduct from 1908 to 1913. This aqueduct still supplies about 30% of the city’s water and its concrete has endured extreme conditions for over 110 years.

The Hoover Dam project also benefited from our natural pozzolan, relying on the material to control heat generation and prevent internal cracking in its massive concrete pours.

Historical references:

How Natural Pozzolan Fixes Modern Concrete

Ordinary Portland cement concrete is strong but contains many microscopic pores, making it vulnerable to water, chemicals, and cracking. As it hydrates, it forms calcium silicate hydrate (CSH) but also leaves behind weak calcium hydroxide (CH). Water and salts move through these weak points, leading to deterioration and corrosion over time.

The Pozzolan “Second Engine”

Natural pozzolan acts as a vacuum for these weak spots by chemically transforming calcium hydroxide into additional CSH. This ongoing pozzolanic reaction densifies the concrete, making it stronger and more durable as time passes, rather than peaking at 28 days and degrading thereafter.

Further reading:

ASTM C618: The Standard Behind “ASTM C618 Class N Pozzolan”

Engineers typically specify natural pozzolan using the ASTM C618 Class N standard, which outlines the chemical and physical requirements for coal ash and natural pozzolans in concrete. ASTM C618 ensures these materials meet performance needs as supplementary cementitious materials (SCMs).

ASTM C618 Classifications

  • Class F: Low-calcium coal ash, primarily a pozzolan.
  • Class C: Higher-calcium coal ash, with both pozzolanic and cement-like properties.
  • Class N: Raw or calcined natural pozzolans—volcanic ashes, tuffs, pumicites, and certain clays.

EMI’s CEME'TPOZZ is classified as ASTM C618 Class N natural pozzolan. It meets or exceeds all requirements.

Key Requirements

Physical tests include fineness, strength activity index, water requirement, soundness, and density. Chemical requirements set limits on silicon, aluminum, and iron oxides, sulfur trioxide, and loss on ignition. These ensure Class N pozzolans enhance concrete durability, lower permeability, and resist sulfate attack.

References:

EMI’s Natural Pozzolan: CEME'TPOZZ (ASTM C618 Class N)

Environmental Minerals Inc. operates the China Lakes mine, the source for the original Los Angeles Aqueduct pozzolan. CEME'TPOZZ is the same class of material that helped create legendary infrastructure, now produced with modern quality control and at industrial scale, meeting all ASTM C618 Class N requirements.

CEME'TPOZZ – Technical Profile

  • Type: ASTM C618 Class N natural pozzolan (volcanic ash).
  • Chemistry: High combined silica, alumina, and iron oxide content on an ignited basis, low loss on ignition, no crystalline silica (per independent testing).
  • Physical properties: High fineness, angular interlocking particles, light color ideal for architectural use.

Independent testing confirms CEME'TPOZZ meets all relevant standards for chemistry and performance.

References:

Fly Ash vs. Natural Pozzolan: Why the Market Is Shifting

Historically, the industry used Class F fly ash because it was inexpensive and widely available. However, with coal plant closures and quality variability, supply is shrinking. In contrast, ASTM C618 Class N natural pozzolan—like CEME'TPOZZ—offers reliable supply, consistent quality, proven durability, and a better environmental profile.

  • Supply security: Stable geological deposit, not affected by coal plant closures.
  • Consistency: Uniform mineralogy from a single source.
  • Durability: 2,000-year history versus a few decades for fly ash.
  • Performance: Lower permeability, better resistance to sulfates and ASR, sustained strength gain.
  • Environmental profile: Lower embodied CO₂, less processing, natural origin.

The Geometry Advantage: Angular Particles

Unlike the smooth, spherical shape of most fly ash particles, EMI’s natural pozzolan features angular, interlocking particles. This unique geometry:

  • Enhances packing density by reducing voids in the paste and mortar fraction.
  • Provides mechanical interlocking, improving early compressive strength.
  • Mitigates microcracks, slowing crack propagation and extending service life.
  • Strengthens the interfacial transition zone for improved bond and load transfer.

In summary, EMI’s pozzolan enhances both the chemical and mechanical properties of concrete.

Performance Benefits: Where CEME'TPOZZ Excels

Mass Concrete & Heat Control

In large pours, like dams and thick slabs, cement generates heat that can cause internal cracking. Natural pozzolan lowers peak temperatures, reducing thermal gradients and cracking risk. This makes it a preferred choice for mass concrete projects.

Durability in Harsh Environments

Natural pozzolan improves performance in challenging settings:

  • Marine/coastal structures: resists chloride attack.
  • Sulfate-rich soils and groundwater: improved sulfate resistance.
  • Freeze–thaw climates: refined pores for higher durability.
  • Wastewater/chemical exposures: denser matrix, better resistance.

ASR (Alkali–Silica Reaction) Mitigation

Natural pozzolan helps control ASR by consuming alkalis and refining the pore structure, reducing expansion and cracking risks, even with standard aggregates.

Long-Term Strength Gain

While many mixes plateau at 28 days, concrete with natural pozzolan matches or exceeds control strengths at 28 days and surpasses them at later ages, making it ideal for long-life infrastructure.

Efflorescence Control & Aesthetics

By reducing calcium hydroxide and controlling pore connectivity, natural pozzolan minimizes white, powdery efflorescence and enhances the appearance of architectural and masonry concrete.

Decarbonizing Concrete with CEME'TPOZZ

Portland cement production is responsible for a significant share of global CO₂ emissions. Replacing cement with EMI’s natural pozzolan allows for meaningful cement substitution, reducing mix-level embodied CO₂. Because the volcanic material is already naturally calcined, it avoids additional process emissions.

AGRIPOZZ™ – Natural Conditioner for Crop Soils

Beyond concrete, EMI’s AGRIPOZZ™ brings pozzolan’s mineral benefits to agriculture as a soil conditioner. Engineered from volcanic pumice/pumicite, AGRIPOZZ™ contains a high silica content with significant alumina and iron oxide.

Benefits for Soils and Crops

  • Improves water retention and reduces runoff in sandy soils.
  • Enhances air and nutrient retention around roots.
  • Reduces soil compaction, promoting better root development.
  • Offers a cost-effective alternative to perlite for broadacre use.

AGRIPOZZ™ is suited to broadacre agriculture, specialty crops, and growing media, with applications tailored by agronomists.

Who We Serve

Environmental Minerals supplies material buyers and specifiers—including ready-mix producers, cement manufacturers, DOTs, precast builders, and agricultural producers. Support includes technical data, mix design optimization, and long-term supply planning for infrastructure programs.

Getting Started with EMI

We offer:

  1. Technical documentation (ASTM C618 test data, pozzolanic activity, durability metrics).
  2. Consistent supply (competitive pricing, logistics, multi-year options, stable geology).
  3. Engineering support (integration assistance, project-specific optimization).

Key references for your project team include ASTM C618, ACI 232.2R, FHWA ASR guidance, and MIT Concrete Sustainability Hub resources.

Additional information on pozzolan characteristics, critical minerals, and internal research reports is maintained in the Project Vault document research area, led by team member Colin. For access to detailed laboratory reports and technical memoranda, please contact Environmental Minerals Inc.