PUMICE IN INDUSTRY
Applications for Pumice
By virtue of its spectacular origin (resulting in a unique set of physical and chemical characteristics), pumice is a truly versatile and valuable industrial and agricultural performer. Though found in abundance worldwide, there are a rare few commercial pumice deposits that are of the purity, hardness, brightness and chemical composition necessary to be of wide value to industry. The expertise with which it is mined and refined and the ability to deliver it where it needs to be—on spec and on time—figures into the value equation as well.
Hess Pumice Products sources a pumice deposit in demand worldwide, and supplies that pumice to a variety of industries for a variety of uses, refined and graded to meet scores of different specs. We’ve been in the business of pumice for over 60 years, and, quite frankly, we’re very good at it. An overview of the myriad ways pumice is used in industry and product formulations is presented below.
Pumice Aggregate in Concrete
DECORATIVE PRECAST CONCRETE VENEER
Manufactured (cast) stone veneer is an enduringly popular exterior and interior finish that imparts the sculpted durability and beauty of stone finishes without the cost and the weight of natural, hand-cut rock. Glass fiber reinforced concrete (GFRC) panels and products provide beautiful and cost-effective finishes for buildings. Pumice is the key ingredient to these lightweight decorative construction materials.
LIGHTWEIGHT INSULATING PUMICE CONCRETE
Pumice aggregate concrete has several advantages over conventional concrete in many construction applications. Most significant of these is its unique lightweight quality. Other key factors such as workability, resistance to harsh weather conditions, and a high R-value, make pumice concrete the choice for demanding structure construction needs.
LIGHTWEIGHT STUCCOS AND BONDING MORTARS
Lightweight bonding mortars performance-enhanced with proven chemistry meet the demanding and diverse needs of today’s professional. Lightweight mortars can certainly handle the typical bonding needs—whether laying up a block wall or laying down a durable tile surface. But where lightweight mortars really shine is in meeting the nuanced needs of those working with cast stone, brick, and board-form veneer products. Like bonding like.
Concrete Performance Pozzolan
Natural. Sustainable. Green. Highly effective. And, quite frankly, nothing new—the Greeks and the Romans were wise to the functional benefits of powdered pumice as a supplementary cementitious material. In our modern concrete mix designs, as a percentage of cement replacement, pumice pozzolan is really brings it.
MITIGATE ALKALI-SILICA REACTION (ASR)
In regions of the world with reactive aggregate, ASR is a relentless concrete assassin, causing a slow-motion explosion that shatters concrete from within, bringing on the expense and grief of replacement well before the structure’s engineered lifespan. Pumice pozzolan mitigates or eliminates the ravages of ASR.
IMPROVE INFRASTRUCTURE AND BUILDINGS
Hess led the renaissance of pumice pozzolan concrete over the last decade. The Romans leveraged the amazing improvements in longevity and performance imparted to concrete by the addition of fine-grained pumice (evidenced by their still-standing concrete structures). Today, our pozzolan products fortify modern high-performance concretes in a variety of ways. Rigorous research shows the clear advantages and super-charging properties imparted by HessPozz and Hess UltraPozz in modern concrete formulations. An added bonus, both in terms of cost and reducing concrete’s carbon footprint, is that pumice pozzolan can replace a significant portion of the Portland cement in the mix design.
STRUCTURAL PRECAST CONCRETE
For critical-component precast concrete applications, Hess UltraPozz imparts category-leading results in every essential concrete-performance quantification. Combine the density and durability imparted by pumice pozzolan with lightweight pumice aggregates and things really get interesting.
CEMENTITIOUS ULTRAFINE INJECTION GROUTS
The go-to workhorse for soils that need stabilized or microfractures in leaky rock that need sealed are cementitious injection grouts. An ultrafine graded, plasticizer-tweaked, pozzolan-charged cementitious grout not only significantly expands the application/use parameters, it also extends the functional lifespan of the cured grout from decades to centuries.
POZZOLAN + LIME PLASTERS
Anciently, the Romans used a mixture of hydrated lime and fine-grained pumice to form strong and incredibly durable concrete, mortar, and plaster. Today, HessPozz is used in a line of all-natural pozzolanic hydraulic lime (PHL) plaster products that put the strength, durability and beauty of the old-world masters in the capable hands of today’s plasterers. For structures built from breathable alternative building materials (strawbale, hempcrete, adobe and other earthen materials), a lime plaster rendering is only plaster solution that preserves the valuable breathability of the wall system.
Polishing, Abrasive and Exfoliating Applications
Pumice built its reputation in the industrial products arena by virtue of its exceptional polishing and grinding character. The Hess Pumice deposit, in particular, proved so naturally pure and just-right hard that it put Hess Pumice on the international map.
Pumice is a non-botanical, sustainable, gentle exfoliant that has been used successfully for years in cosmetics and personal care products like exfoliating scrubs, heavy-duty hand soaps, and dental polishing compounds. With the widespread ban on plastic microbead use, pumice takes an even bigger role as an effective-yet-gentle exfoliant. The wide variety of cosmetic grades (and grade blends) provides an extensive application profile.
Hess Pumice is used extensively worldwide for crucial surface finishing processes—the friable pumice particles fracture and remain sharp-edged when processed to even a sub-micron size—making pumice ideal for use as a mild abrasive for finishing glass, metal, wood, leather, and plastics. It also makes an excellent tumbling media for anything from small parts like buttons to textiles—like stone-washed denim.
SAND BLASTING MEDIA
The same amorphous-safe (non-crystalline), hard-yet friable, glassy-sharp character that makes pumice a high-performance grit for delicate surface grinding and polishing compounds also plays in sand blasting applications.
FINE FINISHING GRIT
It is those final micro-sanding and rubbing steps in finishing wood (or metal) that truly take the quality of a piece from average to amazing. Fine and microfine pumice grades produce excellent finish-rubbing results.
A growing body of research has shown pumice to be an effective filtering media for drinking water. The foamy structure and natural purity of Hess Pumice makes it ideal to capture and hold cyanobacterial toxins and other impurities found in fouled drinking water. The excellent filtration and absorption properties of pumice make it useful for other cleaning and filtering uses, such as purifying oils or removing odor.
In-Suspension Texturizing Grit
The light, foamed-glass character of pumice, even at small granular grades, makes it a terrific grit for adding tooth and texture to viscous liquids like gessos, paints, primers, and industrial coatings. Light and sponge-like, it stays in suspension and spreads move uniformly throughout the application.
Horticultural & Agricultural Applications
Expanded perlite is a well-known and widely used soil amendment. Pumice is the physiochemical equivalent of perlite, but being naturally calcined (expanded to a frothy stone in high heat) by volcanic action, it does not need treatment in an energy-intensive furnace to achieve its useful form. For large-scale horticultural applications—compost or native soil amendment, seed coating, soilless grow media—pumice is the economical choice.
AMENDING SOIL PERFORMANCE
Because of its highly porous nature, pumice holds water and air—both critical to well-conditioned, aerated soils. This makes Hess Pumice an excellent soil conditioner for use in potting media and garden soils—and even for improving the soil profile of critical and hard-used turf applications such as golf greens and sports fields. Reclamation sites, wetlands improvement projects, storm water control constructs and runoff-filtering ecology embankments—they too perform better with the addition of pumice. Because pumice is non-organic, it will not decompose or burn. Pumice is also pH neutral.
Several factors combine to make pumice desirable as a stand-alone soilless soil. It has an ideal form factor to drain quickly but hold enough moisture and nutrients in the surface nooks and crannies to meet plant needs. The drainage and watering rate is highly customizable—dialed in by adjusting the particle sizes of the pumice in the grow media. Pumice is light enough to ease the burden on shelves and racks and backs, but substantial enough to anchor the pot and support the plant. Pumice does not swell when wet, breakdown with use, or decompose.
PONICS GROW MEDIA
Pumice stones provide a combination of benefits to high-efficiency soilless grow systems that no other grow media can: pH neutrality; an ideal balance between drainability, moisture retention and gas exchange in the root zone; a naturally porous structure excellent for bacteria / microbe colonization; grippy, interlocking edges and enough mass to stay stable and provide plant support.
A blend of compost and pumice provides benefit on two fronts: pumice improves the composting process itself and, once blended into the soil along with the finished compost, pumice works as a long-lived soil structure and performance improvement amendment that short-lived compost alone cannot.
Pet and Livestock Care
Pumice has wide utility in livestock husbandry and pet care. Sometimes the application is straight-up obvious—like bathing dust for Chinchillas and Degus, chickens, and other dust-bath-loving critters.
The moisture and odor-absorbent properties of pumice are directly applicable to confined livestock applications, like horse stalls and chicken coops. And, when removed and composted along with the manure and other litter, pumice keeps on giving. Pumice helps retain nitrogen (and control odor) during the composting process and then contributes to the soil the compost is blended into by increasing the ability of the soil to hold moisture and nutrients while permanently improving soil structure (see amending soil with pumice, above).
Microfine Functional Filler and Extender
The safe, non-crystalline silica nature of pumice, the near-white color of Hess pumice in particular, and its chemically and environmentally inert nature makes pumice an appealing choice as a functional filler and extender. Hess produces five carefully-processed microfine, Non-Crystalline Silica (NCS) grades for use in paint, industrial coatings, stains, epoxies, rubber compounds, caulkings, and plastics.
Other Uses for Pumice
PUMICE AND LEED CERTIFICATION
The U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) certification program has been embraced worldwide and is the predominant green building certification system in the U.S. As the program evolves and grows, so too does the need to understand the fit—both in cost and performance—of a wide range of effective materials and processes to meet the requirements. We've written a white paper that focuses on identifying the LEED categories and options where pumice and pumice-enhanced products can be valuable contributors to the goal of LEED certification (download below).
Fine-grade pumice, dusted inside a mold, prevents the plastic or rubber material from binding and sticking to the inside of the mold wall. Pumice powder is also used to avoid sticky (and expensive) problems by those who practice the delicate art of applying gold leaf.
When used for purposes of blast mitigation, cellular solids, like pumice, collapse at the cellular level beneath the force of the blast, absorbing much of the blast energy and contributing to damage containment. Lightweight, abundant and easily processed to any spec, pumice has proved to be effective and economical for blast mitigation media in missile and bomb encasements, blast mats, and other blast-protection products.
Think of pumice as a mineral sponge: inert, stable, lightweight and much more effective than sawdust, clay compounds and textiles. The absorption factor of carefully processed pumice is incredible. Pumice will absorb and hold oils and impurities and so is useful as a dry absorbent for chemical and petroleum spills. The absorption factor can be customized with the blend of particle sizes.
LIGHTWEIGHT GEOTECHNICALL FILL
Projects calling for a lightweight fill—like bridge approaches, road embankments, and mechanically stabilized earth walls—are ideal uses for light, tightly-binding pumice.
GET A PUMICE SAMPLE
If you’d like to sample a pumice grade (or several), we have a nice selection of stock pumice grades available to purchase in small quantities via our Pumice Products Store.
If you’d like to run tests and trials using our pumice in your commercial product formulation or industrial process, please contact us at email@example.com with your request. We look forward to answering your questions, helping you select the best grade for your process, or helping you explore the fit of pumice for your needs. PLEASE include your name, your company or organization, pertinent project details, ship-to address, and preferred contact information in the sample request email.