Lightweight Pumice Aggregate

Concrete is a crucial component of modern civilization, forming the utilitarian backbone of our physical infrastructure. Lightweight pumice aggregates expand the possibilities in concrete mix designs.

Pumice Concrete

There is nothing new about lightweight pumice concrete. The Romans were using it 2000 years ago. Roman engineers and builders have been celebrated for their enduring wonders—especially for the most well-preserved of all Roman architecture, the Pantheon of Rome. The dome itself is a world-class wonder. It was expertly cast using a concrete consisting of hydrated lime cement, fine-grained pumice pozzolan (critical for strength and density) and lightweight pumice aggregate.

Modern scientists have determined that the manageable weight of the Pantheon’s huge, unreinforced concrete dome is attributed to lightweight pumice aggregate, while the secret to Pantheon’s (and other Roman structures) longevity is pozzolan: fine-grained pumice (known as pozzolana to the Romans).

Modern pumice concrete formulations are composed of Portland cement, pumice rock, pumice sand, and water. In critical precast or special-duty infrastructure applications, a ultrafine pumice pozzolanic powder (Hess UltraPozz) is also added. Pumice concrete is proportioned, mixed, and placed in a similar manner as conventional sand-and-gravel concrete, is used in the same applications, and is screed, troweled and finished with the same equipment.


A significant advantage of pumice aggregate concrete is its lightweight quality—up to one-third lighter than conventional sand-and-gravel concrete. This trait contributes to a decrease in structural steel costs and, consequently, job costs. ••• ]


The lower thermal conductivity of pumice concrete means less heat loss. Hess pumice concrete has 4X the R-value of typical sand-and-gravel aggregate concrete. This significant R-value increase both slows heat transfer and eliminates or reduces moisture condensation on walls and ceilings. ••• ]


Another key factor is workability, particularly in nailing, sawing, and drilling. As for appearance, pumice concrete has a uniform color and texture. Acoustical ratings are higher for pumice concrete as well.


Pumice concrete has superior resistance to harsh weather conditions like freezing and thawing. This, plus its inherent high R-value, makes pumice concrete desirable for colder climates and dramatic changes in weather. ••• ]


Lightweight aggregates are reactive, and if used with ordinary Portland cement without the mitigating effects of a reactive pozzolan, the concrete inevitably develops a nasty ASR problem—a reaction between the high silica content in the aggregate and the alkali in the hydrated cement paste. ••• ]


Lightweight pumice concretes are ideally suited in applications where 3500 psi or less is acceptable and where thermal and lightweight properties are desired.

STRUCTURES. Homes, industrial facilities, and commercial buildings—especially those located in extreme temperature locations—benefit from the inherent insulative properties (4x R-value; reduced or eliminated moisture condensation) and resistance to freeze/thaw cycles afforded by pumice aggregate concrete.

OIL WELL CEMENTS. Oil and gas wells need to deliver under the harshest of conditions—from deep under the North Sea to the sands of Arabia—and the well cement has to be equal to the challenge. ••• ]

SYNTHETIC FRACKING SAND. Hess produces a carefully refined pumice powder used to make a high-performance synthetic fracking sand.

PUMICE-BLENDED CEMENT TO MITIGATE ASR. Research done by the University of Utah quantified the mechanism and effectiveness of pumice-blended cement on creating concrete resistant to alkali-silica reaction (ASR).

MANUFACTURED STONE. Pumice aggregates and pumice pozzolan are used extensively in the production of stone and brick veneer products, glass fiber reinforced panels, architectural elements, statuary, and other precast concrete products. Pumice makes the ideal aggregate: it can be economically sized for any needed mold shape, provides bulk and strength yet results in a lightweight product that can be used as interior and exterior finishes without additional supporting ledges. And the consistent clean white color of Hess pumice means the color of every crafted stone or brick starts and finishes rich and vibrant.

PUMICE CONCRETE BLOCKS. Pumice-aggregate CMUs are lighter to lift and place and mean less dead weight loads...and still meet compressive strength requirements. Blocks made with Hess pumice produce a lightweight concrete structure that is the whitest masonry available. This block is popular for commercial, professional, and residential buildings and for decorative uses such as fireplaces, planters and walls.

BLOCK FILL. Pumice concrete, or even the dry pumice alone, is used as an insulating cavity fill for concrete block walls.

CONCRETE CANOES. Pumice is the ideal lightweight competition aggregate for serious concrete canoe teams. See canoesofconcrete.com for information, resources, recommended grades, test samples and production material ordering.

Precast Decorative Concrete

The usefulness of the pumice aggregate expands what is possible with prefabricated products: architectural accents, stone veneers, stucco and binding mortars that are insulating, lightweight, and freeze-thaw resistant.


Exterior and interior finishes of natural stone and fired brick are persistently popular and classically beautiful, lending interest and character with texture, shape, depth, and color. A stone or brick finish is also extremely durable and requires little care. But materials and installation costs—especially for dressed native stone—can be quite expensive. ••• ]


Glass fiber reinforced concrete (GFRC) products apply lightweight mold-cast concrete on a grand scale, resulting in panels that beautifully skin and protect large structures and finish interior walls and ceilings with fascinating, enduring detail. For such surfacing panels, the balance between weight, strength, and durability is a delicate one—bright, hard, lightweight Hess pumice aggregate and superfine Hess Ultrapozz (pumice pozzolan) make it all work to impressive advantage.

Case in point: Nippon Electric Glass (Japan) and NEG America, world-spanning supplier of materials and support to GFRC panel manufacturers, stock and distribute Hess UltraPozz.


Pumice concrete is molded and formed into statuary, ornate exterior furniture, counter tops, fence panels, fireplace surrounds and more. It is the perfect choice for casting cornices, columns, copings and other architectural elements (especially in restoration work). And the same intense demands of color purity, durability, strength, load-reduction and portability hold true for all these products and applications as well—demands that our bright, pure, carefully refined pumice meet or exceed.


Strength and less weight can co-exist effectively. For those casting and shipping precast concrete products, decreasing per-piece weight while retaining strength and performance means significant savings in shipping costs. Hess Pumice’s expertise in strong, lightweight pumice-concrete mix designs for molded concrete products could be just what you need to increase your reach — to competitively ship your precast concrete products farther and more efficiently.

Stuccos and Bonding Mortars

Carefully engineered and blended bonding mortars and stuccos using lightweight pumice aggregate hold several advantages. Product performance consistency, bag after bag. Less freight-weight costs to get it to the jobsite and less installed weight on walls and floors. Easier handling for the mixing and installation crews. Safer handling as well—no respirable crystalline silica means no long-term health issues from working with powdered mortar and stucco mixes on the jobsite.


The popularity of cast veneers in stone, brick, and board profiles is a combination of several factors: cost, variety, form consistency (for rapid, repeatable installation), lightweight character (reduced structural support and materials handling requirements) and convincing mimicry. That kind of product achievement needs a complimentary bonding mortar—one that completes the presentation and works in performance lock-step for the life of the veneer envelope. Like bonding like. A bonding mortar made from the same lightweight aggregates used in the decorative finish pieces makes perfect sense, bringing the same lightweight character, the same freeze-thaw behavior, the same durability, effectively completing the cohesive performance of the entire veneer.


Lightweight-aggregate plasters are used for conventional stucco renderings, either as traditional scratch and brown coats, or in one-coat applications, including varieties for spray application. Also used when a leveling, functional bonding substrate is needed under a tile or veneer cladding.

Insulating Concrete linked technical data sheet 3/4 x 3/8 MN | linked technical data sheet 3/4 x 5/16 MN |
linked technical data sheet 1/8 Fines MN
Manufactured Stone Veneers linked technical data sheet 3/8 Fines MN |
linked technical data sheet 3/8 x #8 MN |
linked technical data sheet 1/8 Fines MN
Concrete Blocks/MCUs linked technical data sheet 1/8 Fines MN
Stucco and Bonding Mortars linked technical data sheet 1/8 Fines MN
Geotechnical Fill linked technical data sheet 3/4 x 3/8 MN
NOTE: The grades selected above are typical and representative. Please contact us regarding your project, product, or process for help to determine the ideal grade or grade blend.


pumice store logo

arrow 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.

arrow If you’d like to run tests and trials using our pumice in your commercial product formulation or industrial process, please contact us at salesteam@hesspumice.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.


We know pumice. We’ll answer your questions, help determine the ideal grade for your needs, get you sample grades for testing, or help figure out the logistics for getting pumice to you—whatever’s needed.

R&D: (208) 766-4777 x111

Sales: (208) 766-4777

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